2024 JSCCR临床实践指南：大便失禁（修订版第二版）

Keywords

fecal incontinence, anal incontinence, guidelines, GRADE, obstetric anal sphincter injuries, incontinence-associated dermatitis

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Procedures for Preparation of the JSCP Practice Guidelines for Fecal Incontinence (Revised Second Edition)

The specific procedures for preparing the guidelines were in accordance with the Minds Manual for Guideline Development 2017 and 2020 and are as follows:

(1) Creation of Scope

Title: JSCP Practice Guidelines for Fecal Incontinence 2024 (Revised Second Edition)

Purpose: To improve the symptoms of fecal incontinence (FI) and the quality of life of patients with FI by promoting treatment and care, and to produce an English translation of the Practice Guidelines for Fecal Incontinence 2024 (Revised Second Edition), originally published in Japanese in 2024[1], and to make the translated version publicly accessible.

Topic: Treatment and care of FI in adults

Intended users: Medical professionals treating patients with FI, caregivers, and the public. Intended for treatment and care in medical facilities, in long-term care facilities, and at home.

Important clinical issues: It is necessary to (1) clarify how to clinically evaluate FI; (2) clarify how to clinically evaluate special conditions (older adults, dementia, and low anterior resection syndrome); (3) clarify tests necessary to determine the treatment policy for FI; (4) evaluate the usefulness of dietary, lifestyle, and bowel habit instructions in the treatment of FI; (5) evaluate the indications and usefulness of drug therapy in the treatment of FI; (6) evaluate the indications and usefulness of pelvic floor muscle training/biofeed-back therapy in the treatment of FI; (7) evaluate the indica-

and usefulness of transanal irrigation in the treatment of FI; and (8) evaluate the indications and usefulness of surgical therapy in the treatment of FI.

Relationship to the existing guidelines: A revised edition of the Japanese Practice Guidelines for FI 2017.

Scope covered by the practice guidelines: FI in adults. Fec cal incontinence in children is excluded.

(2) Evidence Collection and Evaluation Methods

During the literature review, in addition to the literature search by the persons or groups in charge, a literature search was conducted with the cooperation of the Japan Medical Library Association as follows:

Databases searched: PubMed, Ichushi Web, and Cochrane Library

Search period: until December 2022

Search languages: English, Japanese

For each paper, we assigned a research design[2] (Table 1), considered various risks of bias (Table 2) in accordance with the Minds Manual for Guideline Development 2020, and discussed and determined the level of evidence (Table 3) with reference to the GRADE system[3].

(3) Creation of Statements and CQs

Diagnostic and treatment methods that are likely to be widely used in specialized centers were explained as a "statement" in each section, and the degree of recommendation was described. In contrast, for statements regarding definitions, epidemiology, etiology, and other factors not directly related to diagnostic and therapeutic interventions, as well as for diagnostic and therapeutic methods that can only be performed in a limited number of facilities or whose evaluation is not established, no recommendations or their degree were provided. To provide recommendations for

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Table 1. Research Design.

(1) Meta: Systematic review/meta-analysis of randomized controlled trials (2) Random: Randomized controlled trial (3) Non-random: Non-randomized controlled trial (4) Cohort: Analytical epidemiological study (cohort study) (5) Case-control: Analytical epidemiological study (case-control study) (6) Cross-sectional: Analytical epidemiological study (cross-sectional study) (7) Case series: Descriptive studies (case report and case series) (8) Guidelines: Clinical practice guidelines (9) Not stated: Opinions of expert committees or individual experts that are not based on patient data (not used as evidence)

Table 2. Risk of Bias Assessment Items.

|Selection bias|(1) Random sequence generation: Is there a detailed description of whether patient allocation has been randomized? (2) Concealment: Are the patients to be enrolled concealed from the person in charge of enrolling them?| |---|---| |Performance bias|(3) Blinding: Are participants blinded? Are care recipients blinded?| |Detection bias|(4) Blinding: Are outcome assessors blinded?| |Attrition bias|(5) Intention-to-treat (ITT) analysis: Are the principles of ITT analysis set forth and adhered to for dropouts from follow-up? (6) Outcome reporting bias: Are the data for each primary outcome fully reported (including inclusion and exclusion data in the analysis) ? (7) Other biases: Selective outcome reporting: Are there any outcomes that have been listed in the study protocol but not reported? Early trial termination: Has the trial been terminated early because of benefits or adverse events? Other biases|

Table 3. Level of Evidence.

|A|High-quality evidence (High) We are very confident that the true effect lies close to that of the estimated effect| |---|---| |B|Moderate-quality evidence (Moderate) We are moderately confident in the effect estimate The true effect is likely to be close to the estimated effect, but it may be substantially different| |C|Low-quality evidence (Low) We have little confidence in the effect estimate The true effect may substantially differ from the estimated effect| |D|Very low-quality evidence (Very Low) We have very little confidence in the effect estimate The true effect is likely to be substantially different from the estimated effect|

making appropriate decisions regarding diagnosis and treat- ment when several clinical options are available, CQs were established and included in each section.

(4) Determination of the Strength of Recommendation

The strength of recommendation was determined based on the following assessment items: (1) the strength of evidence regarding the outcome, (2) the balance between benefit and harm (burden) experienced by patients, (3) cost (insurance coverage, cost-effectiveness, etc.), and (4) patient wishes. In addition, the strength of the recommendation was determined after examining the conditions for adopting the GRADE approach recommended by the Minds Tokyo GRADE Center[4] in accordance with the Manual for

Guideline Development[5,6]. Consensus was reached with a consensus rate (agreement with the strength of recommendation) of 70% or more through voting among the 11 Preparation Committee members using the nominal group technique. The expression of the strength of recommendation was as shown in Table 4.

(5) External Evaluation and Public Comments

From October 2023, the Evaluation Committee reviewed the second draft, and the Preparation Committee reviewed the opinions expressed again. The draft that had been revised based on the reviews was published on the website of the Japan Society of Coloproctology as the final draft, and public comments were solicited from members, nonmem-

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|Strength of Recommendation|| |---|---| |Strong Recommendation|Recommend "to implement" Recommend "not to implement"| |Weak Recommendation|Propose "to implement" Propose "not to implement"|

bers, and the general public as an external evaluation from February 27 to March 25, 2024. The comments received were collected and reflected in the final manuscript as much as possible.

(6) Revisions

This is the revised second edition of the guidelines, and the Japan Society of Coloproctology Guideline Committee plans to continue revising the guidelines every 5-7 years.

(7) Preparation Cost

The Japan Society of Coloproctology bears all expenses for the preparation of these guidelines. No funding has been received from any company.

Flowcharts

The diagnostic and treatment flowcharts for fecal incontinence are summarized in Figure 1 and 2.

I. Definition, Epidemiology, Pathophysiology, Causes, and Risk Factors of Fecal Incontinence

A. Definition

Statement

* Fecal incontinence is defined as “symptoms of involuntary or uncontrolled loss of feces from the anus.”

* Gas incontinence is defined as "symptoms of involuntary or uncontrolled loss of flatus from the anus."

* Anal incontinence is defined as the combination of fecal and gas incontinence.

Commentary

Fecal incontinence (FI) is the term used for the loss of feces. In Japan, it was defined as described in the Japanese Practice Guidelines for FI 2017. This definition has been adopted for the term "Fecal Incontinence used in epidemiological surveys and indications for treatment. Since then, although guidelines have been updated overseas, no major changes have been made to the definition, partly to avoid confusion.

The International Consultation on Incontinence (ICI) published the revised "Incontinence 6th Edition" in 2017, providing definitions that "fecal incontinence is the involuntary loss of feces," "flatus incontinence is the involuntary loss of rectal gas or flatus," and "anal incontinence is the involu-

tary loss of feces and/or flatus and/or mucus”[7]. While the ICI defines FI as “involuntary loss of feces,” our guidelines define it as “symptoms of involuntary or uncontrolled loss of feces from the anus,” considering passive FI (involuntary loss of feces) and urge FI (uncontrolled loss of feces), which are the typical symptoms of FI.

The guidelines published by the American Society of Colon and Rectal Surgeons in 2015 defined incontinence as "the uncontrolled passage of feces or gas over at least 1 month's duration, in an individual of at least 4 years of age, who had previously achieved control." This definition has not been altered since 2007 and is characterized by the inclusion of age and the symptomatic period without distinguishing between FI and gas incontinence[8].

The guidelines published by the American College of Gastroenterology in 2021 defined FI as "involuntary loss of stool from the anus" and anal incontinence as including loss of flatus, stating that "FI is the involuntary loss of solid or liquid feces. The more general term, anal incontinence, also includes involuntary loss of flatus"[9].

The Rome IV Criteria defined it as “recurrent uncontrolled passage of fecal material in an individual with a developmental age of at least 4 years.”

B. Epidemiology

Statement

$\bullet$ In Japan, the prevalence of fecal incontinence among individuals aged ≥65 years is 8.7% among men and 6.6% among women.

* Similarly, the prevalence of anal incontinence, including gas incontinence, is 34.4%.

Commentary

The prevalence of fecal incontinence (FI) varies widely among reports, ranging from 0.9% to 19.5% according to a 2016 systematic review[10]. This is because of differences in the definition of FI, survey methods, and conditions, such as the symptomatic period and age of inclusion among reports[11]. According to a systematic review of literature up to 2014, the median prevalence of FI was 7.7% but with a wide range of 2.0%-20.7%, with 8.1% (2.3%-16.1%) among men and 8.9% (2.0%-20.7%) among women, demonstrating no gender difference, and the prevalence tended to be lower among younger people, with 5.7% among individuals aged 15-34 years[12]. In addition, a systematic review of studies on nursing home residents aged ≥65 years showed a high prevalence of FI at 42.8%[13].

Although there are few epidemiological studies on FI in Japan, a home interview survey of 1,405 men and women aged ≥65 years found that the prevalence of FI, including occurrences less than once a month, was 8.7% among men and 6.6% among women[14]. A recent questionnaire survey of 463 individuals (mean age of 35.6 years, 71% female) indicated that the prevalence of FI, including gas incontinence,

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![graph TD\n A1[Initial clinical assessment • PI, PH, comorbidities, medication, physical examination • Evaluation of FI severity （symptoms and impact on QoL） • Exclusion of structural diseases through colonoscopy, etc.] -->|*1| A2[Differential diagnosis of organic diseases: CRC, IBD, rectal prolapse, and rectovaginal fistula]\n A1 -->|*2| A3[Initial conservative therapy • Therapy for diet • Lifestyle • Bowel habit & skin care • Review & modification of medication （e.g., laxatives） • Drug therapy （polycarbophenolcalcite, loperamide, etc.）]\n A3 -->|（Insufficient symptomatic improvement） *3| A4[Specialized clinical re-evaluation • PI, PH, comorbidities, medication, physical examination • Evaluation of FI severity with scoring system （symptoms and impact on QoL）]\n A4 -->|*3| A5[Evaluation with specialized examinations • Anorectal manometry & sensory test • Anal ultrasonography • Pelvic MRI • Defecography]\n A5 -->|*3| A6[Specialized conservative therapy • Pelvic floor muscle training • Biofeedback therapy • Transanal irrigation]\n A5 -->|*5| A7[Experimental conservative therapy • Tibial nerve stimulation • Anal electrical stimulation • Anal insert device • Vaginal insert device]\n A6 -->|*4| A8[Surgery （Fig 2）]\n A7 --> A8\n](1/parseimages/figure3b709d99bb3e4f1f9648ee1dfd5b87f1_0_2.png) Figure 1. Flowchart of the initial management, specialized examination, and conservative therapy for fecal incontinence.

PI: present illness, PH: past history, FI: fecal incontinence, QOL: quality of life, CRC: colorectal cancer, IBD: inflammatory bowel disease

Each bold, thin and broken line in the figure indicates that it has higher grade of recommendation in this order.

*1: If patients with fecal incontinence (FI) exhibit alarming signs, including blood stool, recent changes in bowel habits, unexpected body weight loss, and palpable abdominal and/or rectal tumor, on initial clinical assessment, organic diseases should be differentiated with colonoscopy etc. If organic diseases including colorectal cancer, inflammatory bowel disease, rectal prolapse, and rectovaginal fistula are revealed, they should be treated first.

*2: If there are no such organic diseases, patients with FI should be treated with initial conservative therapies.

*3: If sufficient symptomatic improvement is not achieved with the initial conservative therapies, specialized examinations should be performed, followed by specialized conservative therapies and/or surgery at specialized institutions.

*4: If sufficient symptomatic improvement is not achieved with the specialized conservative therapies, surgery should be considered.

*5: Tibial nerve stimulation, anal electrical stimulation, anal insert device, and vaginal insert device may be performed as experimental therapies only in clinical trials.

was 34.4%, with gas incontinence alone accounting for the majority at 30.4% and FI at 4.0%. Additionally, the prevalence of FI was higher in women, with 15.5% in men and 42.7% in women[15].

Among epidemiological studies in the United States, a telephone survey in the 1990s on 6,959 adults living in Wisconsin reported a prevalence of FI, including gas incontinence, of 2.2%. The condition was more common among women, physically restrained individuals, and individuals with poor general health [16]. A mail questionnaire survey on men and women (778 men and 762 women) aged ≥50 years found a prevalence of 17.0% among men and 24.6% among women [17]. In contrast, a telephone questionnaire

survey that included a relatively younger age group showed a relatively lower prevalence in the representative sample population (2,229 women and 2,079 men) aged ≥29 years at 7.7% (6.0%-9.4%) among men and 8.9% (7.2%-10.5%) among women[18]. A mobile app-based questionnaire survey conducted in 2015 (in participants aged ≥18 years) found that among 71,812 participants with valid responses, 14.4% had experienced FI, of whom 33.3% were symptomatic with FI within 1 week[19].

Regarding foreign epidemiological studies conducted outside the United States, a website-based questionnaire survey conducted in the Netherlands in 2015 on participants aged ≥ 18 years showed that the prevalence of FI was 7.9% among

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![graph TD\n A1[Specialized examination and conservative therapy(Fig.1)] -->|*1(Insufficient symptomatic improvement)| A2[Severe spinal cord impairment]\n A1 --> A4[Anal sphincter disruption]\n A2 --> A3[Antegrade continence enema Stoma]\n A4 --> A5[Absent]\n A4 --> A6[Present]\n A5 -->|*2| A7[Sacral neuromodulation]\n A5 -->|*5| A8[Ventral rectopexy Antegrade continence enema Graciloplasty Stoma]\n A6 -->|*3| A7\n A6 -->|*4| A9[Anal sphincteroplasty]\n A6 -->|*5| A8\n A7 -->|*3| A8\n A8 -->|*6| A7\n A9 -->|*5| A8\n](1/parseimages/figure71951de05af948e19314d2c671a4d728_0_2.png) Figure 2. Flowchart of surgery for fecal incontinence.

*1: Antegrade continence enema or stoma should be considered if fecal incontinence (FI) is caused by sever spinal cord impairment.

*2: Sacral neuromodulation is the first line surgical therapy for FI if it is not caused by anal sphincter disruption.

*3: If FI is mainly caused by anal sphincter disruption, either anal sphincteroplasty or sacral neuromodulation should be performed.

Its decision should be made after full discussion with patients with FI, referring to the Clinical Question 4.

*4: If sufficient symptomatic improvement is not achieved with one of the anal sphincteroplasty and sacral neuromodulation, the other one may be performed.

*5: The surgery in the second line can be performed without the surgery in the first line being performed, depending on the preference and conditions of each patient with FI.

*6: If the first-line surgical therapies fail to achieve sufficient symptomatic improvement, the surgery in the second line should be considered.

In contrast, the second line can be tried first depending on the preference and conditions of each patient with FI. If the second line fails, the first line can follow it.

both men and women, based on 1,259 valid responses[20]. In addition, a home visit survey of 1,253 women in Taiwan revealed that the prevalence of FI was 2.8% and the prevalence of gas incontinence was 8.6%[21].

C. Pathophysiology and causes

Statement

$\bullet$ Fecal incontinence is caused by the following pathological conditions or factors occurring alone or in combination: 1 Abnormal stool consistency (soft or watery stool) 2 Decreased anal pressure 3 Impaired anorectal sensation

4 Defecation disorders

5 Abnormal rectal capacity, pressure, or compliance

6 Colon dysfunction

7 Cognitive or motor dysfunction

Commentary

1 Abnormal stool consistency (soft or watery stool)

Irritable bowel syndrome (IBS), inflammatory bowel disease, functional diarrhea, radiation enteritis, and malabsorption syndrome may cause soft stools, which are difficult to retain in the rectum, leading to fecal incontinence (FI)[18,22]. In recent years, diarrhea caused by microscopic colitis, despite the absence of macroscopic abnormalities, has been reported to also cause FI[23]. In addition, diarrhea

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caused by various drugs causes FI. In particular, antibiotics, antitumor drugs, peptic ulcer drugs, immunosuppressants, and antigout drugs may cause severe diarrhea, which may lead to FI; thus, caution is required[24]. In addition, antidiabetic drugs, hematopoietic agents, and nonsteroidal anti-inflammatory drugs (NSAIDs) can cause diarrhea and soft stool. Furthermore, FI associated with diarrhea caused by daily indulgences—such as coffee, alcohol, and spices—and food allergies has also been reported[25].

2 Decreased anal pressure

Anal sphincter dysfunction refers to a decrease in resting anal canal pressure due to abnormal function of the internal anal sphincter or decreased voluntary contraction pressure due to abnormal function of the external anal sphincter [26]. Depending on the cause, anal sphincter dysfunction can be divided into two types: those caused by weakening or injury of the anal sphincters and neurological ones caused by damage to the innervating nerves [27]. The most common causes of anal sphincter injury are perineal lacerations during childbirth and anorectal surgery [28]. In contrast, the causes of neuropathy include spinal cord disease, spinal cord injury, multiple sclerosis, diabetes mellitus, autonomic nervous system abnormalities, and pudendal neuropathy during vaginal delivery [27]. The internal anal sphincter, external anal sphincter, and cushion tissues of the anal canal are involved in the resting anal canal pressure [29]. Cushion tissues consisting of blood vessels under the epithelium of the anal canal account for 10%-20% of the resting pressure, and a decrease in cushion tissues may cause FI [30]. In addition, the anorectal angle formed by the puborectalis muscle, a pelvic floor muscle group, is involved in fecal continence, although it is not related to anal pressure [31,32].

3 Impaired rectoanal sensation

When feces stored in the sigmoid colon move into the rectum, the rectal wall is stretched, and when the stretching stimulus is transmitted to the cerebral cortex via the sacral nerve, it triggers a sensation of the need to defecate. The rectoanal inhibitory reflex triggered by the stretching of the rectal wall by feces brings some of the rectal contents to the area near the dentate line, where the rectal contents are perceived and their nature (solid, liquid, or gas) is identified, and this process is called the sampling reflex[33]. If this rectal sensation decreases, the person will not be aware of the presence of stool in the rectum, which may result in rectal fecation impaction, leading to overflow passive FI. In a study of 1,351 patients, 27% of patients with FI accompanied by constipation had rectal hyposensitivity, indicating that rectal hyposensitivity is an important cause of FI[34]. In some cases, FI is caused by the inability to distinguish between stool and gas in the rectum due to a decrease in the sampling reflex. This impaired rectoanal sensation is caused by disorders of the central or peripheral nervous system. The caures include central nervous system disorders, such as

cerebral infarction, spinal cord injury, and multiple sclerosis, and peripheral neuropathy caused by diabetes mellitus and other diseases. Other causes include aging, dementia, and Parkinson's disease[27].

In contrast, rectal hypersensitivity also causes FI. In patients with IBS, the rectum is also hypersensitive, and feces moving into the rectum causes an excessive defecation reflex and excessive rectal contractions, resulting in urge FI[35].

4 Defecation disorders

Defecation disorders, in which stool cannot be properly expelled from the rectum, may cause stool remaining in the rectum to leak sometime after defecation[31]. Impaired co-ordination during defecation, such as paradoxical contrac-tions, may cause residual stool. Morphological abnormali-ties, such as rectocele and rectal intussception, may also lead to incomplete stool evacuation and FI.

5 Abnormal rectal capacity, pressure, or compliance

Reservoir dysfunction due to decreased rectal capacity and compliance can be induced by surgery, such as rectal resection, and rectal inflammatory diseases and radiation en-teritis[36]. Acquired anorectal disorders, such as rectal pro-lapse and rectal intussusception, can also cause FI because of decreased stool retention capacity. In addition, neoplastic lesions of the anorectal region can cause FI.

6 Colon dysfunction

In patients with IBS, diarrhea and frequent bowel movements caused by functional abnormalities of the colon may lead to FI[22]. In addition, in low anterior resection syndrome (LARS), a defecation disorder following rectal resection, the sigmoid colon is often resected to a certain extent along with rectal resection, causing a decrease in the capacity of the sigmoid colon to store stool and resulting in frequent bowel movements, frequent short bowel movements, irregular bowel movements, and urge FI[36].

7 Cognitive or motor dysfunction

FI may occur when the patient cannot perform original defecation behavior because of cognitive or physical motor dysfunction despite normal defecation functions, such as anorectal and colonic functions. This condition is referred to as dysfunctional FI, which is broadly divided into cognitive dysfunctional FI and motor dysfunctional FI[37,38].

Cognitive dysfunctional FI occurs when a person lacks social and hygienic concepts, such as "defecation is to be done in the toilet," due to impaired cognitive function caused by disorders, such as dementia, resulting in defecation in places other than the toilet or inability to remember where the toilet is located.

Motor dysfunctional FI is the result of impaired physical motor function due to factors such as lower limb amputation following an accident and age-related muscle weakness (sar-copenia), which causes a person to take too long to move to the toilet after feeling the urge to defecate.

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D. Risk factors for onset

Statement

* Risk factors for the onset of fecal incontinence include physical conditions, such as age and gender; comorbidities, such as diabetes mellitus and IBS; and obstetric conditions, such as the number of deliveries, home delivery, first delivery, and forceps delivery.

Commentary

Risk factors for the onset of fecal incontinence (FI) include physical conditions, comorbidities, and obstetric conditions.

Among physical conditions, age is a clear risk factor for FI, and the majority of epidemiological studies, including young adults, have suggested a clear association between age and FI[14,16,17,39-41]. This may be due to an age-related decline in physical abilities, such as muscle strength and cognitive function, as well as an increase in comorbities, which are risk factors for FI and are described later. Although many reports have indicated that the prevalence of FI is significantly higher in women than in men[16,17,39,41,42], some have shown no difference in the prevalence of FI between men and women[14,40,43,44], making gender a relatively weak risk factor for FI. Other physical conditions reported as risk factors for FI include obesity (BMI >30)[45,46], poor general health[44,45], and physical disability[16,46].

Systemic comorbidities can also be risk factors for FI. Patients with diabetes mellitus have a higher incidence of FI, and there is a relationship between the degree of blood sugar control and the degree of FI[47]. Patients with IBS[48] and inflammatory bowel disease have a high prevalence of FI[49]. Constipation is the most common cause of FI among children[50]. Urinary incontinence[17,45], overactive bladder[21], and pelvic organ prolapse[21,45] are also associated with FI. Dementia[51] and spinal cord injury[46] have also been reported as risk factors for FI.

Obstetric conditions, such as the number of deliveries[21,39], home delivery[52], First vaginal delivery[53,54], and forceps delivery[55], have been reported as risk factors for FI. In addition, fetal size (weight >4,000 g)[53,55] and prolonged second stage of labor[56] may also be risk factors for gas and FI.

The presence of rectal cancer itself may also be a cause of FI, but the rate of LARS, a defecation disorder following anus-preserving surgery for rectal cancer, is as high as 80%-90%[57], and the number of patients living with defecation disorder even after radical cure continues to increase every year.

II. Diagnosis and Evaluation of Fecal Incontinence

A. Initial clinical assessment of fecal incontinence

The initial clinical assessment of fecal incontinence (FI) involves evaluation of its severity and impact on QoL as well as identification of its causes based on medical history, symptoms of FI, and physical examination of the anorectal area. In addition, examinations, such as colonoscopy, are performed as necessary to identify organic diseases, such as ulcerative colitis, that may cause FI. This initial clinical assessment is fundamental for the management of FI, as it is necessary to differentiate FI caused by organic diseases, such as rectal prolapse, and to select appropriate initial conservative therapies.

1. Medical history, observation, and assessment

Statement

* It is recommended to take medical history, including symptoms of fecal incontinence, and to observe and assess the patient's cognitive and motor functions, as they are useful for evaluating the severity of fecal incontinence and its impact on quality of life, as well as for identifying the cause.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: D

Abstract

The symptoms of fecal incontinence (FI) are classified as urge FI, passive FI, and mixed FI, in which both coexist, and stool consistency is evaluated using the Bristol Stool Form Scale. Because FI is often caused by multiple factors, medical history should be taken considering various pathological conditions, causes, and risk factors. History of the present disease should focus on details related to FI, such as its onset and severity, and on daily bowel habits and activities related to FI. In addition, patients' past medical history, obstetric history, and comorbidities associated with FI should be reviewed.

Because cognitive and motor dysfunctions can also cause FI, the observation and assessment of cognitive and motor functions are important for the treatment and care of FI. A bowel diary is useful for assessing the occurrence and factors of FI and for managing oral medications.

Commentary

a. History of present illness

The symptoms of FI are classified as urge FI, passive FI, and mixed FI, in which both coexist[58]. Urge FI is "a symptom of feeling the urge to defecate but passing feces without being able to hold it until one reaches the toilet," while passive FI is "symptom of not feeling the urge to defecate and passing feces without realizing it." FI is rarely caused by a single factor and is often the result of multiple interrelated causes[28]. In other words, FI is caused by fac-

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 |Type 1|Separate hard lumps like nuts| |---|---| |Type 2|Sausage-shaped but lumpy| |Type 3|Like a sausage or snake, but with cracks on its surface| |Type 4|Like a sausage or snake, smooth and soft| |Type 5|Soft blobs with clear-cut edges| |Type 6|Fluffy pieces with ragged edges, a mushy stool| |Type 7|Watery, no solid pieces|

Figure 3. Bristol Stool Form Scale [65].

tors such as abnormal stool consistency, decreased anal pres- sure, impaired rectoanal sensation, defecation disorder, ab- normal rectal capacity, pressure or compliance, colon dys- function, and cognitive or motor dysfunction, occurring alone or in combination (see "I-C. Pathophysiology and Causes").

When anal sphincter dysfunction is the main cause of FI, a decrease in internal anal sphincter function is likely to cause passive FI due to a decrease in resting anal canal pressure, whereas a decrease in external anal sphincter function may cause urge FI due to decreased anal canal voluntary contraction pressure[59]. In contrast, even if the anal sphincters are perfectly normal, if rectal sensation is decreased and the patient does not feel the urge to defecate even when there are feces in the rectal, fecal impaction may occur, resulting in overflow passive FI. Furthermore, patients with IBS, in whom rectal sensation and contractility are increased, may experience urge FI even when the anal sphincters are perfectly normal because the strong rectal contractions that occur as a defecation reflex in response to hypersensitivity to the urge to defecate cause the feces in the rectum to be expelled. In a survey of 472 patients with IBS living in the United States and Sweden, nearly 20% had FI on at least 1 day per month[60]. Another theory is that passive FI occurs when feces remaining in the rectum leak after defecation because they cannot be completely evacuated during defecation due to rectal intussception or rectocele or because the rectal wall invaginates into the rectal lu men, inducing the rectoanal inhibitory reflex, resulting in decreased resting anal canal pressure[61].

During the interview, medical history should be collected regarding the patient's daily bowel habits and FI, focusing on the risk factors for FI while considering the various pathological conditions described above. For this purpose, a

detailed bowel movement record and description of the patient's daily life, including dietary habits, are recommended[58,62,63]. Although medical history alone may not provide an accurate estimate of the pathophysiology or cause of FI, it may help determine the need for treatment and further examination, including specialized examinations.

1) Questions regarding daily bowel habits

$\bullet$ What were your bowel movements like before the onset of FI?

$\bullet$ When and how did they change?

* Are you using medications such as laxatives, enemas, irrigation, or suppositories? Since when and to what extent?

$\bullet$ How often do you normally have bowel movements?

$\bullet$ What is your usual stool form? (Described based on the Bristol Stool Form Scale) (Figure 3)

$\bullet$ Do you usually have a roughly fixed time for bowel movement? (Regular or irregular?)

$\bullet$ Do you strain excessively when defecating? If you strain, to what extent and for how long?

* Can you distinguish between stool and gas? Can you distinguish between liquid and solid stool?

$\bullet$ Do you feel abdominal pain or bloating before defecation?

$\bullet$ Do you need assistance with using a finger or hand to defecate?

* Can you wipe yourself clean after defecation?

* How active are you in your daily life?

2) Questions on FI

$\bullet$ When did the first episode of FI occur? How has it changed over time since then?

$\bullet$ Was there a trigger that caused FI?

* Can you perceive if you have fecal leakage? Are you experiencing consciously uncontrolled fecal conti-

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nence?

$\bullet$ Is there leakage of gas, mucus, liquid stool, or solid stool? How often, how much, and what is the stool form?

$\bullet$ Can you hold your bowel movements? How long can you hold them?

* Can you hold your flatus? How long can you hold it?

$\bullet$ Do you have stool leakage after defecation?

$\bullet$ Do you have stool leakage during sleep?

* Does FI interfere with your daily activities? If yes, what kind of effects, how often, and to what extent?

* Are you using hygiene products, such as pads? If yes, how often and how many pieces?

3) Questions about daily life related to FI

$\bullet$ Dietary intake, indulgences (coffee, alcohol, etc.), and fluid intake

* Smoking history and changes in body weight (BMI)

$\bullet$ Oral medications such as laxatives and psychotropic drugs

$\bullet$ Daily routine (waking up, eating, going to school/working, bedtime, etc.)

$\bullet$ Living environment, including toilets (accessibility to toilets, use of warm-water bidet and toilet seat, and Japanese-style or Western-style toilets)

* Pain caused by defecation posture or difficulty maintaining defecation posture (joint contracture, etc.)

Stool consistency is one of factors affecting FI[64], and diarrhea can cause urge FI. In contrast, chronic constipation, such as rectal fecal impaction, caused by rectal hyposensitivity, can cause passive FI. Because defecation status, including FI, varies greatly by person, it is necessary to confirm the daily bowel habits of each patient and assess the changes in these habits.

It is preferable to evaluate and describe stool consistency using the internationally used Bristol Stool Form Scale (Figure 3)[65]. However, it must be used with the understanding that there may not be perfect agreement among the evaluators. In particular, it is difficult to distinguish between types 2 and 3 and types 5 and 6[66]. When interviewing about symptoms of FI, the degree and time course of FI should be evaluated, considering the pathophysiology, causes, and risk factors of FI. In addition, the living environment, including the toilet environment, and the patient's general condition, including movement restriction, cognitive ability, and level of activities of daily living[67], should be evaluated as factors related to the manifestation of FI symptoms in daily life. Because diarrhea caused by regular medications for comorbidities may be involved in the onset of FI, the patient's medications should be reviewed in detail. Inappropriate use of laxatives for constipation often causes FI. Psychotropic drugs may cause FI by affecting intestinal motility and peripheral nerves[68]. Indulgences, such as coffee and alcohol, can cause FI by affecting intestinal motility

and stool consistency[67]. Furthermore, because obesity is a risk factor for FI, changes in body weight should also be monitored[64].

As described above, FI is often caused by multiple factors; thus, it is necessary to take medical history considering various pathological conditions, causes, and risk factors. Taking a history of present illness, including symptoms of FI, is useful for evaluating the severity of FI and its impact on quality of life and for identifying the causes of FI. The European guideline[69] and the ASCRS Clinical Practice Guidelines[70] also "strongly recommend" that "the cause of FI should be identified based on medical history" as an expert opinion.

b. History and comorbidities

The following diseases and physical conditions are factors associated with FI, as well as history and comorbidities that may be risk factors for FI (see "I-C. Pathophysiology and Causes").

$\bullet$ Diseases and physical conditions that affect intestinal motility

$\bullet$ Diarrhea, constipation, enteritis, IBS, diabetes mellitus, history of cholecystectomy, etc.

$\bullet$ Diseases and physical conditions that affect rectoanal sensory function

$\bullet$ IBS, vaginal delivery (pudendal neuropathy due to overextension of nerves), spinal nerve disease or injury, chronic constipation, anal malformation and its history, diabetes mellitus, dementia, etc.

$\bullet$ Diseases and physical conditions that affect anal sphincter function

$\bullet$ Vaginal delivery (anal sphincter injury due to perineal lacerations or pudendal neuropathy due to overexten-sion of nerves), anal surgery or trauma, spinal nerve disease or injury, aging, etc.

$\bullet$ Diseases and physical conditions that affect rectal capacity and extensibility

$\bullet$ History of intraperic surgery, such as in the rectum or uterus, IBS, history of radiation therapy, inflammatory bowel disease, constipation (chronic distension of the rectum), rectal and anal cancer, etc.

$\bullet$ Diseases and physical conditions that reduce stool evacuation performance

$\bullet$ Movement restriction due to cerebral infarction, age-related generalized muscle weakness, dementia, etc.

$\bullet$ Other diseases and physical conditions that may cause FI

$\bullet$ Actions and side effects of oral medications (laxatives, etc.), hemorrhoids, anal fistula, rectal prolapse, rectal intussusception, inflammation of the rectum and perineum, rectal fecal impaction, etc.

1) Obstetric history

For obstetric history, in addition to the presence or absence of a history of childbirth, confirm the mode of deliv-

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ery (vaginal or cesarean section), whether using forceps or vacuum, the number of deliveries, the degree of perineal laceration, the birth weight of the infant, and postpartum defecation status. Obstetric anal sphincter injuries (OASIS) are an important cause of FI in women. According to a study that used endoanal ultrasound for evaluation, the incidence of OASIS is 27%-35% in primiparas [71]; however, its occurrence does not necessarily indicate the development of anal incontinence (including gas incontinence). In a prospective study by Sultan et al. [72] who evaluated 79 primiparas before and after vaginal delivery using endoanal ultra-sonography, OASIS occurred in 28 primiparas (35%) after vaginal delivery; however, among them, only about one-third, or 10 primiparas (13%), developed anal incontinence or fecal urgency.

Anal incontinence developed in 1.2% of women after vaginal delivery, even if OASIS did not occur; thus, it is necessary to consider anal sphincter injury and pudendal neuropathy during delivery as the cause of anal incontinence after delivery[73]. Risk factors for the onset of anal incontinence after vaginal delivery include third- or fourth-degree perineal laceration (anal sphincter injury), forceps or vacuum delivery, maternal obesity, and advanced age[55,73-75].

2) History of surgery and radiation therapy

A history of hysterectomy, anal surgery, rectal surgery, and other surgeries, such as cholecystectomy, as well as a history of radiation therapy to the pelvic region, may cause FI.

FI caused by anal surgery (for anal fissure, anal fistula, hemorrhoids, etc.) is attributed to direct surgical manipulation of the anal sphincters and anal sphincter injury resulting from hyperextension of the anal canal during surgery[76]. In LARS, a defecation disorder after rectal resection[36], or after total colectomy and ileoanal anastomosis for ulcerative colitis, FI can occur. This may be due to decreased fecal re-tention capacity following colon or rectal resection and de-creased anal sphincter function, and changes in stool consis-tency and the sensation of stool retention. Hysterectomy also causes urinary and FI[77]. In addition, surgery for prostate cancer or rectal and anal cancer may be combined with ra-diation therapy, which further increases the risk of FI[63,78]. In addition to surgery in the anus or pelvic cavity, diarrhea after cholecystectomy is a risk factor for FI[63].

3) Spinal or spinal cord diseases and a history of pelvic trauma

Spinal or spinal cord diseases (spinal cord injury, spina bifida, spinal canal stenosis, etc.), history of spinal or spinal cord surgery, and history of pelvic and sacroiliac trauma directly affect the sensation and motor nerves distributed in the pelvic floor. In addition, diarrhea and constipation caused by autonomic neuropathy mediated by spinal nerves can cause FI[63,79-81].

4) Diabetes mellitus

Diabetes mellitus is recognized as a risk factor for FI because it is accompanied by systemic peripheral neuropathy and impairs intestinal motility and sensory nerves of the rec-tum and motor nerves of the anal sphincters [49,67,82]. In a survey of 8,657 participants, symptoms of FI were corre-lated with blood glucose control [47].

5) Neuromuscular disease

In neuromuscular diseases such as Parkinson's disease, multiple sclerosis, lateral sclerosis, and scleroderma, autonomic and motor nerves are systemically impaired, whereas peripheral neuropathy occurs in the rectum, anal sphincter, and pelvic floor muscles[83]. Rectal capacity, sensation, and extensibility are decreased, and the contractility of the anal sphincters is also decreased, causing FI[63,67].

In contrast, when the central nervous system is impaired because of cerebral infarction or other causes, FI is often caused by impaired rectoanal function, cognitive decline, and decreased motor functions, such as mobility and movement restrictions[63,68].

6) Urinary incontinence

Urinary and FI have common pathogenesis resulting from impaired pelvic floor muscles and nerves. The prevalence of postpartum urinary and FI is 6%-8%, but the incidence is higher in primiparas over 35 years of age who undergo for-ceps or suction delivery[67,84,85]. About one-third of fe-male patients with urinary incontinence who gave birth ex-perience FI, which is a higher complication rate than that among men[54]. The onset of urinary and FI is correlated with depression (odds ratio 2.3), indicating that psychologi-cal factors are involved in the onset of incontinence.

7) Diseases causing abnormal stool consistency, such as constipation and diarrhea

Chronic enteritis, IBS[48,86], and diseases that cause abnormal stool consistency, such as constipation and diarrhea, are risk factors for FI[88,87]. IBS, in particular, has a high odds ratio of 2.4 for the onset of FI and is considered a clear risk factor[49].

c. Observation and assessment

Fecal incontinence also occurs when a person feels the urge to defecate but is unable to do so normally because of cognitive impairment or is unable to reach the toilet or undress in time because of motor dysfunction. The former is referred to as FI associated with cognitive impairment, and the latter is referred to as FI associated with motor dysfunction. Both conditions are collectively referred to as dysfunctional FI[88]. Therefore, in older adults in particular, it is necessary to collect the following information and perform careful observation[89,90].

A bowel diary is useful for assessing the complex mechanisms underlying FI (Table 1). In the bowel diary, patients should record information, such as defecation time, stool consistency (using the Bristol Stool Form Scale) and

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Bowel Diary for Fecal Incontinence

Patient Name ( )

|Date|Month/day|e.g. Dec/1|/|/|/|/|/|| |---|---|---|---|---|---|---|---|---| |Bowel Frequency|Bowel movements per day|5 times||||||| |Stool Consistency|Separate hard lumps, like nuts|||||||| |Stool Consistency|Sausage-shaped but lumpy|1||||||| |Stool Consistency|Like a sausage or snake, but with cracks on its surface|||||||| |Stool Consistency|Like a sausage or snake, smooth and soft|1||||||| |Stool Consistency|Soft blobs with clear-cut edges|1||||||| |Stool Consistency|Fluffy pieces with ragged edges, a mushy stool|2||||||| |Stool Consistency|Watery, no solid pieces|||||||| |Medication|Name of medicines|T: tablet, C: capsule, P: pack, D: drop||||||| |Medication|Calcium polycarbophil|2-2-2 T|-|-|-|-|-|-| |Medication|Loperamide|1-0-1 C|-|-|-|-|-|-| |Medication|NEW LECICARBON Suppositories|1 piece, morning|-|-|-|-|-|-| |Medication|||-|-|-|-|-|-| |Frequency of Fecal Incontinence|FI times per day|3 times||||||| |Volume Character (liquid or solid) of Leaked Stool|Dot-like stain|||||||| |Volume Character (liquid or solid) of Leaked Stool|Linear stain|Liquid 1||||||| |Volume Character (liquid or solid) of Leaked Stool|A teaspoonful|||||||| |Volume Character (liquid or solid) of Leaked Stool|A tablespoonful|||||||| |Volume Character (liquid or solid) of Leaked Stool|A tablespoonful|||||||| |Volume Character (liquid or solid) of Leaked Stool|Large amount||Solid 1, Liquid 1|||||| |Others (Anything to be recorded)|Diet|Ate sweets and drank juice brought by my grandchild||||||| |Others (Anything to be recorded)|Symptoms|Slight pain at my bottom||||||| |Others (Anything to be recorded)|Daily activities|Kept sitting on a chair most of the day||||||| |Others (Anything to be recorded)|Concerns|How to take medicines|||||||

amount, presence, or absence of the urge to defecate, presence or absence of FI, duration, type and amount of laxatives and antidiarheals, other related symptoms, such as abdominal pain and perianal pain, and changes in diet and environment. In addition, a bowel diary is useful for determining the effectiveness of treatment and care. Bowel diaries have been used to determine the efficacy of FI treatment in RCTs[91], prospective interventional studies[92], and retrospective cohort studies[93]. Furthermore, the bowel diary is useful for patients to reflect on the onset triggers and occurrence of FI and manage oral medications.

1) Information to be collected regarding cognitive and motor functions

$\bullet$ Do you have the urge to defecate? Are you able to express it? $\bullet$ Are you aware of the need to go to the toilet to defendate? $\bullet$ Do you know the exact location of the toilet? $\bullet$ Can you move to the toilet smoothly? Do you need a walking aid? $\bullet$ Do you face any difficulties in opening and closing the toilet door, using toilet paper, and using the toilet flush lever? $\bullet$ Can you put on and take off clothes and underwear by yourself? How long does it take? $\bullet$ Can you wipe off your buttocks after defecation?

$\bullet$ Do you know the exact location of the toilet?

$\bullet$ Can you move to the toilet smoothly? Do you need a walking aid?

$\bullet$ Do you face any difficulties in opening and closing the toilet door, using toilet paper, and using the toilet flush lever?

$\bullet$ Can you put on and take off clothes and underwear by yourself? How long does it take?

* Can you wipe off your buttocks after defecation?

$\bullet$ Can you ask someone else to help with things that you cannot do yourself? (Is there someone whom you can ask? Are you comfortable asking for help?)

* Can you wash your hands after defecation?

2) Bowel diary (Table 5)

2. Anorectal examination and evaluation

Visual inspection (including anoscopy and proctoscopy) and palpation (including digital anorectal and vaginal examination) of the anorectal area, focusing on factors associated with the onset of fecal incontinence, should be conducted, following medical history taking and general physical and anal examinations.

a. Visual inspection

Statement

* Visual inspection is recommended because it is useful for evaluating the pathophysiology of fecal incontinence and identifying its causes.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: D

Abstract

Visual inspection is useful for evaluating the pathophysiology of fecal incontinence (FI) and identifying its causes by observing the external appearance of the anus at rest, including its shape, the condition of the surrounding skin, the presence or absence of scars, and the movement of the anus and perineum during contraction of the anal sphincter and straining. It is also useful for evaluating the state of FI and identifying the cause.

Commentary

Although no studies have directly evaluated the usefulness of visual inspection in the management of FI, a physical examination of the anorectal area, including visual inspection, is "strongly recommended" as an expert opinion in the European guideline[69] and is summarized as "an essential

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component of the evaluation of patients with FI” in the American Society of Colon and Rectal Surgeons Clinical Practice Guidelines[94].

At rest, check the symmetry of the anus and perineum; presence of stool, mucus, or blood on the area; and presence or absence and extent of anal or perineal scars (position, size, and shape) from anal surgery, perineal lacerations, or episiotomy as well as superficial skin lesions (dermatitis, flare reaction, avulsion, and maceration)[69,94-96]. In addition, observe the condition of anal closure and the presence or absence of visible anal lesions, such as rectal prolapse, mucosal prolapse, and hemorrhoids. In women, confirm the distance between the vaginal orifice and the anus and perform a visual inspection with attention to the direction of the scars caused by episiotomy, as the risk of anal sphincter injury is reported to be higher with a midline episiotomy than with a mediolateral episiotomy during vaginal delivery[97,98].

During anal sphincter contraction, observe whether the closure of the anus with contraction is circumferential and uniform and whether indentations or retractions appear due to anal sphincter defects. During straining, observe the descent of the anus and perineum. Excessive perineal descent suggests that the pelvic floor muscles are flaccid, which can cause FI[99].

Visual inspection using an anoscope or proctoscope is useful for the diagnosis of organic abnormalities that may cause FI, such as anorectal tumors, hemorrhoids, rectal ulcers, and scars from anal surgery (hemorrhoidectomy, fistula surgery, Whitehead operation, and anal atresia surgery).

b. Palpation

1) Palpation of perianal area

Statement

$\cdot$ Palpation is recommended to evaluate the sensation of the perianal skin in patients with suspected anorectal hyposensitivity.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: D

Abstract

Evaluation of perianal skin sensation by palpation and assessment of anal sphincter defects by perianal skin compression are useful for identifying the causes of fecal incontinence (FI) in patients with suspected anorectal hyposensitivity.

Commentary

Although no studies have directly evaluated the usefulness of palpation in the management of FI, a physical examination of the anorectal area, including palpation, is "strongly recommended" as an expert opinion in the European guideline[69] and is summarized as "an essential component of the evaluation of patients with FI" in the American Society of Colon and Rectal Surgeons Clinical Practice Guidelines[94].

In patients with suspected anorectal hyposensitivity, such as those with spinal cord impairment and older adults, evaluate perianal skin sensation by palpation. Evaluation of perianal skin sensation is particularly important in patients presenting with rectal fecal impaction, as rectal sensation is often decreased. Evaluation of perianal skin sensation is easier when compared with other body parts with apparently normal sensations. The areas of neuropathy that can be diagnosed by palpation according to the area of distribution from the spinal nerves to the skin sensory nerves are S3: outer perianal area, and S4-5: perianal area[95,100]. Therefore, when perianal skin sensation has decreased, S3-5 sacral neuropathy is suspected. In addition, if S2-4 sacral nerves are intact, an anocutaneous reflex, called "anal wink", is present, in which the external anal sphincter contracts when the perianal skin is stimulated with a needle[101]; however, this reflex is not observed in S2-4 sacral neuropathy.

It is useful for identifying significant anal sphincter injury to evaluate subcutaneous anal sphincter defects with resistance to light pressure on the perianal skin by palpation with fingers. However, failure to identify an abnormality by palpation does not necessarily mean that an anal sphincter defect does not exist because minor defects cannot be identified with such a palpation. In women, palpation of tissue integrity in the perineum between the anus and vagina is useful for assessing the consequences of perineal lacerations during vaginal delivery.

2) Digital anorectal examination (including digital vaginal and bidigital examinations)

Statement

* Digital anorectal examination is recommended to be performed because it is useful for evaluating the pathophysiology of fecal incontinence and identifying its causes.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: B

Abstract

Digital anorectal examination is useful for evaluating the pathophysiology of fecal incontinence (FI) and identifying its causes by assessing rectal tumors and masses, rectal fecal impaction, rectocele, anal canal tone, voluntary contraction pressure, anal canal deformity and asymmetry, as well as the presence or absence and degree of pelvic floor incoordination.

Commentary

Several studies have examined the usefulness of digital anorectal examination for the treatment of FI compared with anal manometry and endoanal ultrasonography [96,102-107], although no RCTs have investigated it. The European guide-line [69] “strongly recommends” as an expert opinion that “Inspection and physical examination of the anorectal region should be performed to assess anorectal pathology and/or fecal impaction and to evaluate anal state/tone at rest and dur-

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Japanese Practice Guideline for Fecal Incontinence 2024

ing voluntary effort". In addition, digital anorectal examination is summarized as "an essential component of the evaluation of patients with FI" in the American Society of Colon and Rectal Surgeons Clinical Practice Guidelines[94] and is recommended with "Grade of Recommendation B" by the 6 th International Consultation on Incontinence[108].

When a mass that seems to be a tumor is palpated in the rectum by digital rectal examination, colonoscopy is necessary to diagnose and differentiate organic diseases such as rectal cancer. If a significant amount of fecal mass is palpated in the rectum, passive FI due to the mechanism of overflow FI associated with rectal fecal impaction is very likely[109]. After removal of the fecal mass, therefore, periodic rectal emptying should be performed with scheduled defecation regimens and bowel habit instructions. In addition, anorectal physiology tests should be considered to evaluate rectal sensation because it may be decreased in patients with fecal impaction. If a rectocele is found in women, consider performing defecography, as residual stool in the rectum due to structural evacuation disorders, such as rectocele, may be the cause of post-defecation passive FI[108].

Digital anal examination is useful for evaluating the contractility of the anal sphincter, and when performed by an experienced examiner, the contractility of the internal and external anal sphincters and the puborectal muscle can be evaluated fairly accurately[108]. This is based on the fact that several studies have reported a high correlation between anal canal tone and voluntary contraction pressure evaluated by digital anal examination and maximum resting pressure and maximum voluntary contraction pressure evaluated by anal manometry, respectively[96,102-107]. In particular, Orkin et al.[105] developed the Digital Rectal Examination Scoring System (DRESS: Table 6), which evaluates resting pressure and squeeze pressure on a six-point scale (DRESS score) from 0 to 5 as a subjective evaluation method of anal canal tone and voluntary contraction pressure by digital anal examination. In 303 patients with defecatory concerns, each DRESS score was compared with the results of anal manometry. The resting DRESS score showed a good correlation with mean maximum resting pressure by anal manometry with resting DRESS scores of 0: 21 mmHg, 1: 39 mmHg, 2: 48 mmHg, 3: 72 mmHg, 4: 94 mmHg, and 5: 128 mmHg (correlation coefficient: 0.82). In addition, the squeeze DRESS score showed a good correlation with mean maximum voluntary contraction pressure by anal manometry with squeeze DRESS scores of 0: 46 mmHg, 1: 67 mmHg, 2: 108 mmHg, 3: 156 mmHg, 4: 239 mmHg, and 5: 368 mmHg (correlation coefficient: 0.81).

Digital anal examination for the evaluation of anal canal deformity and asymmetry has low diagnostic accuracy for mild anal sphincter defects and disruptions, but is useful for the diagnosis of severe defects and disruptions[96,106,107].

Table 6. Digital Rectal Examination Scoring System (DRESS).

|Resting Score|Resting Score| |---|---| |0|No discernible tone at rest and an open or patulous anal canal| |1|Very low tone| |2|Mildly decreased tone| |3|Normal| |4|Elevated tone and snug| |5|Very high tone, a tight anal canal, and difficult to insert a finger| |Squeeze Score|Squeeze Score| |0|No discernible increase in tone after squeezing| |1|Slight increase| |2|Fair increase but below normal| |3|Normal| |4|Strong squeeze| |5|Very strong squeeze, to the point of being painful to the examiner|

Quoted from Orkin BA, et al. [105].

Dobben et al.[96] compared the diagnosis of external anal sphincter defects by digital anal examination with that by endoanal ultrasonography in 312 patients with FI. Their study revealed an agreement rate of 100% for severe defects of 150°-270° by endoanal ultrasonography but a low agreement rate of 61% for defects of 90°-150° and 36% for defects of less than 90°. In addition, Jeppson et al.[106] examined the diagnostic accuracy of anal sphincter disruptions by endoanal ultrasonography. The sensitivity of digital anal examination was demonstrated to be high (82%), whereas the specificity was low (32%). Therefore, when the diagnosis of the anal sphincter disruptions is made by digital anal examination, it is relatively reliable, and at the same time, the disruptions are likely to be severe. In contrast, when a diagnosis of no anal sphincter disruption is made by digital anal examination, it is less reliable, and it is possible that minor disruptions may be overlooked.

When the patient is asked to strain as if defecating during digital anorectal examination, and pelvic floor incoordination is detected, in which the puborectal muscle and external anal sphincter contract without the ability to remain relaxed, this may indicate a functional defecation disorder. If residual tool in the rectum due to functional defecation disorder is suspected of causing post-defecation passive FI, consider performing a defecography or rectal balloon expulsion test[110]. The diagnostic accuracy of pelvic floor incoordination by digital anorectal examination is relatively high, with a reported sensitivity of 75%-93% and specificity of 59%-87% compared with diagnosis by anal manometry or balloon expulsion test[110,111].

Digital vaginal and bidigital examinations are performed in the same manner as digital anorectal examinations. Digital vaginal examination can evaluate the fragility of the rec-

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tovaginal septum and the presence or absence of uterine or bladder descent caused by abdominal pressure. In addition, enterocele and sigmoidocele can be diagnosed via bidigital examination of the rectum and vagina [112].

As described above, digital anorectal examination is useful for evaluating the pathophysiology of FI and planning its management. In a survey by Wong et al.[113] 6 of 652 gastroenterologists, medical practitioners, and medical students, the rates of performing digital anorectal examination for patients with FI were 100% among gastroenterologists, 83% among medical practitioners, and 79% among medical students. In addition, those with more experience in digital anorectal examination performed it more comfortably, were less likely to be refused by patients, and were more confident in their diagnosis. There are opinions that training using anal models and simulated patients[114] and training under proper supervision in clinical settings[115] are required to perform digital anorectal examinations with confidence. At a minimum, it is important to gain experience in digital anorectal examination to effectively use it in the management of FI.

c. Evaluation of incontinence-associated dermatitis

Statement

$\bullet$ To provide care and treatment appropriate to the cause, the evaluation of the causes and risk factors of incontinence-associated dermatitis is proposed to be performed by categorizing them into systemic (skin fragility) and local factors (butback and perineum environment).

Strength of Recommendation: Weak (Consensus Rate: 90.9%), Level of Evidence: D

Abstract

Incontinence-associated dermatitis (IAD) is caused by contact of the skin with excrement, such as urine and feces. IAD causes unbearable pain, itching, and secondary infections, requiring appropriate prevention, care, and treatment.

In the assessment of IAD, risk factors are evaluated by dividing them into systemic factors (skin fragility) and local factors (buttock and perineum environment). In addition, it is useful to evaluate its severity by scoring using the IAD Severity Evaluation Scale.

Commentary

IAD is caused by contact of the skin with excrement, such as urine and feces. The prevalence of IAD varies depending on the survey participant and facility and is 7.6%-45.7%[116-119] in Europe and the United States and 5.9%-17%[120,121] among residents of long-term care health facilities in Japan. IAD causes unbearable pain, itching, and secondary infections, requiring appropriate prevention, care, and treatment.

When stool comes in contact with the skin because of in- continence, the moisture in the stool causes swelling of keratinocytes and expansion of the interstitial spaces be-

tween corneocytes, resulting in skin maceration. In addition, digestive enzymes in the stool damage the stratum corneum and allow irritants to pass through the skin barrier, thereby causing inflammation. The effects are particularly severe in the case of liquid or soft stools [122]. Furthermore, when diapers or pads are used for incontinence, the skin becomes excessively moist in the hot and humid environment, compromising the skin barrier function. As a result, bacteria and fungi invade the skin, causing epidermal defects, erosions, exudation, vesicle formation, edema, and redness.

1) Assessment of IAD [122-128]

The causes and risk factors are evaluated in the following two categories:

1 Systemic factors (skin fragility)

$\cdot$ Malnutrition

$\bullet$ Aging

$\bullet$ Diabetes mellitus with poor blood glucose control

$\bullet$ Use of immunosuppressants

$\bullet$ Use of anticancer drugs

* Use of steroids

$\bullet$ Use of antibiotics

* Dry skin

2 Local factors (butback and perineum environment)

* Liquid or soft stool

* Coexistence of fecal and urinary incontinence

* Use of diapers, pads, etc.

$\bullet$ Maceration due to excrement

$\bullet$ Pressure or misalignment due to maintaining the same position, such as head elevation or sitting

$\bullet$ Improper skin care (excessive washing and wiping)

2) IAD severity evaluation scale (IAD-set)

The IAD-set, a tool developed to assess IAD in clinical settings in Japan, evaluates and scores two items, namely "I. Skin condition" and "II. The type of excrement attached." "I. Skin condition" is scored for the degree of skin damage and the suspicion of candidiasis in each of the eight sites on the buttocks. "II. The type of excrement attached" is scored based on the characteristics of the attached feces and urine, and the total score is obtained by adding I and II together[124]. The reliability of this scale developed in Japan has been confirmed, and it allows quantitative evaluation. However, effective use requires training due to a large number of observational items and the possibility of confusion in judging skin condition. Therefore, currently, this scale is not widely used in clinical settings; however, further evaluation of its usefulness in clinical practice is expected in the future.

Regarding the statement at the beginning, "To provide care and treatment appropriate to the cause, we propose to evaluate the causes and risk factors of IAD by dividing them into systemic factors (skin fragility) and local factors (but- tock and perineum environment)," there were opinions supporting a strong recommendation during the vote to deter-

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Japanese Practice Guideline for Fecal Incontinence 2024

mine the strength of recommendations in the Guideline Preparation Committee.

B. Patient-reported outcome measures to evaluate symptomatic severity, quality of life, and frequency of fecal incontinence

Statement

$\bullet$ In daily clinical practice, Cleveland Clinic Florida Fecal Incontinence Score (CCFIS) is proposed to be used to evaluate the symptomatic severity and quality of life (QoL) of fecal incontinence. Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

$\bullet$ In daily clinical practice, St. Mark's Score is proposed to be used specifically to evaluate fecal urgency in addition to fecal incontinence symptomatic severity and fecal incontinence-specific QoL.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: D

$\bullet$ In clinical research, both the Fecal Incontinence Severity Index (FISI) and the Japanese version of the Fecal Incontinence Quality of Life Scale (JFIQL) are proposed to be used to evaluate fecal incontinence symptomatic severity and fecal incontinence-specific QoL, respectively.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

$\bullet$ For LARS, the LARS score and JFIQL are proposed to be used to evaluate symptoms of defecation disorders and fecal incontinence-specific QoL, respectively. Additionally, the Japanese version of the EORTC QLQ-C30 and the Japanese version of the EORTC QLQ-C38 are proposed to be used to evaluate general health-related QoL, including the QoL associated with defecation disorders in LARS.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

$\bullet$ In clinical research, treatment success is proposed to be defined as a reduction of at least 50% in the mean number of fecal incontinence episodes per week after treatment compared with that before treatment.

Strength of Recommendation: Weak (Consensus Rate: 90%), Level of Evidence: C

Abstract

For the clinical evaluation of fecal incontinence (FI), it is useful to use Patient-Reported Outcome Measures (PROMs), such as scores and questionnaires, to evaluate the symptomatic severity of FI and its impact on QoL. The Cleveland Clinic Florida Fecal Incontinence Score (CCFIS) (= Wexner Score), St. Mark's Score, and Fecal Incontinence Severity Index (FISI) are commonly used to evaluate the symptomatic severity of FI.

The CCFIS comprises five questions and is suitable for

daily clinical practice because it allows the simultaneous evaluation of the symptomatic severity of anal incontinence (AI) and QoL. The St. Mark's Score comprises seven questions and is also suitable for daily clinical practice with an emphasis on fecal urgency because it allows the evaluation of fecal urgency in addition to five items in the CCFIS. The FISI comprises four questions and is unique in that it evaluates only the symptomatic severity of AI, with each symptom assigned a weighted score. However, because it cannot evaluate QoL, FI-specific QoL evaluation scales, such as the Fecal Incontinence Quality of Life Scale (FIQL), should be used concurrently when the FISI is used for the clinical evaluation of FI.

The LARS score is a suitable scale for evaluating the symptoms of LARS, a defecation disorder that occurs after rectal cancer surgery. Although FIQL is suitable for evaluating FI-skpedi QoL in patients with LARS, the Japanese version of the European Organization for Research and Treatment of Cancer QLQ-C30 (EORTC QLQ-C30) and the Japanese version of the EORTC Colorectal Cancer-Specific Quality of Life Questionnaire 38 EORTC (QLQ-CR38) should be considered when evaluating general health-related QoL, including QoL associated with defecation disorders.

In clinical research, treatment success is commonly defined as a reduction of at least 50% in the mean number of FI episodes per week after treatment compared with that before treatment.

Commentary

For the clinical evaluation of FI, it is useful to use PROMs, such as scores and questionnaires, to evaluate the symptomatic severity of FI and its impact on QoL. Objective evaluation scales allow the comparison of FI severity among different populations and the evaluation of improvement with treatment. The ASCRS Clinical Practice Guidelines[94] recommend, with a low level of evidence, that scores and questionnaires that evaluate the severity of FI and its impact on QoL should be used depending on the situation.

There are many scales for evaluating the severity of FI, including the CCFIS[129], St. Mark's Score[130], FISI[131], and Kirwan classification[132]. In addition, the Initial Measurement of Patient-Reported Pelvic Floor Complaints Tool (IMPACT) was developed to comprehensively evaluate FI as well as constipation, urinary incontinence, symptoms of pelvic organ prolapse, and symptoms of pelvic floor dysfunction, such as sexual dysfunction. IMPACT-B (Bowel function), a part of the IMPACT, is used to evaluate the symptoms of defecation disorders, including FI[133]. Among these, the CCFIS (Table 7), St. Mark's Score (Table 8), and FISI (Table 9) are commonly used to evaluate the symptomatic severity of FI[134].

The CCFIS was previously called the Wexner Score but is now commonly referred to as the Cleveland Clinic Florida

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|Type of Incontinence|Frequency|Frequency|Frequency|Frequency|Frequency| |---|---|---|---|---|---| |Type of Incontinence|Never|Rarely|Sometimes|Usually|Always| |Solid|0|1|2|3|4| |Liquid|0|1|2|3|4| |Gas|0|1|2|3|4| |Wears pad|0|1|2|3|4| |Lifestyle alteration|0|1|2|3|4|

0: Perfect.

20: Complete incontinence.

Never: 0 (never).

Rarely: <1/month.

Sometimes: <1/week, >1/month.

Usually: <1/day, >1/week.

Always: >1/day.

The continence score is determined by adding points from the above table, which considers the type and frequency of incontinence and the extent to which it alters the patient's life.

Quoted from Jorge JM and Wexner SD [129].

||Never|Rarely|Sometimes|Weekly|Daily| |---|---|---|---|---|---| |Incontinence for solid stool|0|1|2|3|4| |Incontinence for liquid stool|0|1|2|3|4| |Incontinence for gas|0|1|2|3|4| |Alteration in lifestyle|0|1|2|3|4| |||||No|Yes| |Need to wear a pad or plug||||0|2| |Taking constipating medication||||0|2| |Inability to delay defecation for 15 min||||0|4|

Never, no episodes in the past 4 weeks;

Rarely, 1 episode in the past 4 weeks;

Sometimes, >1 episode in the past 4 weeks but <1 a week;

Weekly, 1 or more episodes a week but <1 a day;

Daily, 1 or more episodes a day.

Add one score from each row: minimum score = 0 = perfect continence; maximum score = 24

= totally incontinent.

Quoted from Vaizey CJ, et al. [130].

FI Score after the institution, rather than the individual, that developed it[129]. The CCFIS consists of a total of five items, including three items addressing the form (gas, liquid stool, or solid stool) and their frequency of incontinence, as well as two items addressing the frequency of "the use of pads to prevent underwear soiling" and "the impact of FI on daily life," with the total score ranging from 0 (no FI) to 20 (most severe FI). Because it includes the evaluation of gas incontinence, it should actually be referred to as an anal incontinence score, but it is customary to refer to it as a FI score, in addition to the St. Mark's Score and FISI, although

they include gas incontinence as an evaluation item. The advantages of the CCFIS are that it is a relatively simple five-item instrument that allows the simultaneous evaluation of FI symptoms and QoL components, such as the impact on daily life, and that it is widely used historically and internationally. Therefore, from the viewpoint of simplicity, the CCFIS is recommended for evaluating the symptomatic severity of FI and its impact on QoL in daily clinical practice. In contrast, the disadvantages of the CCFIS are that it does not assign weighting to the symptoms to be evaluated, such that 4 points are assigned to daily leakage, regardless of

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|Patient ratings of fecal incontinence|Never|1 to 3 times a month|Once a week|2 or more times a week|Once a day|2 or more times a day| |---|---|---|---|---|---|---| |Solid|0|8|10|13|16|18| |Liquid|0|8|10|13|17|19| |Mucus|0|3|5|7|10|12| |Gas|0|4|6|8|11|12|

Add one score from each row: minimum score = 0 (no fecal incontinence); maximum score = 61 (worst fecal incontinence).

Quoted from Rockwood et al. [131].

whether the patient leaks solid stool or gas, and that the score itself does not necessarily reflect the symptoms of FI alone, as it evaluates FI symptoms and QoL simultaneously. In other words, similar to how FI is called a "symptom of anxiety," even if the FI symptoms have been completely cured by treatment, some patients may continue to use pads and their daily lives may continue to be affected until their anxiety regarding FI is resolved. Thus, their CCFIS can remain at a maximum score of 8. Another disadvantage of the CCFIS is that it cannot evaluate fecal urgency, which can be a major concern for some patients, even if it does not actually lead to FI.

A study comparing the CCFIS and QoL found that patients with a CCFIS >9 had significantly more impaired QoL than those with a CCFIS ≤9[135]. The study recommends achieving a CCFIS ≤9 in clinical practice. In addition, a study that evaluated clinically significant minimally important differences (MID)[136] in FI severity evaluation scales has found that the MID for the CCFIS is 2 to 3 points[137]. For example, in a clinical study, even if a treatment method improves the CCFIS from 12 to 10.5 points, which is a statistically significant difference, an improvement of 1.5 points is not a clinically significant improvement, as it has not reached the MID of 2 to 3 points. In clinical practice, a CCFIS improvement of at least 3 points can be considered a reasonable target.

The St. Mark's Score, also called the Vaizey Score, consists of a total of seven items, including the two items of “presence or absence of fecal urgency” and “presence or absence of antidiarrhe use,” in addition to the five items in the CCFIS, with the total score ranging from 0 (no FI) to 24 (most severe FI)[130]. The advantage of the St. Mark's Score is that it can also evaluate fecal urgency in addition to the evaluation items in the CCFIS. Therefore, St. Mark's Score is recommended for evaluating the symptomatic severity of FI and its impact on QoL in daily clinical practice with an emphasis on fecal urgency. In contrast, the disadvantages of St. Mark's Score are, that similar to the CCFIS, it does not assign weighting to the symptoms to be evaluated, and that the score itself does not necessarily reflect the symptomatic severity of FI, as it evaluates FI symptoms and

QoL simultaneously. The MID for St. Mark's Score is reported as 3-5 points[137]. Therefore, in clinical practice, an improvement of at least 5 points in the St. Mark's Score can be considered a reasonable target.

The FISI consists of four items addressing the form (gas, mucus, liquid stool, or solid stool) and its frequency of continence, with the total score ranging from 0 (no FI) to 61 (most severe FI)[131]. The advantages of FISI are that, unlike CCFIS and St. Mark's Score, it evaluates symptoms only and assigns weighting to the symptoms to be evaluated. However, its advantage of "evaluating only symptoms" may also be disadvantageous because it "can only evaluate symptoms." Therefore, when the FISI is used for the clinical evaluation of FI, a FI-specific QoL evaluation scale should be used concurrently because the goal of management for FI is to improve the patient's QoL by alleviating symptoms.

FI-specific QoL evaluation scales include the FIQL[138] and Modified Manchester Health Questionnaire[139]. In addition, the International Consultation on Incontinence Questionnaire (ICIQ) was developed to comprehensively evaluate QoL related to FI as well as constipation, urinary incontinence, and pelvic organ prolapse; the ICIQ-B (Bowels), which is a part of the ICIQ, is used to evaluate QoL related to defecation disorders, including FI[140]. Among these, the FIQL is the internationally most widely used FI-specific QoL evaluation scale[134].

The FIQL consists of 29 questions categorized into four elements, and the scores are expressed as mean scores, with higher scores indicating better QoL)[138]. The number of questions and the range of scores for each element are as follows: Lifestyle (10 questions, 1-4 points), Coping/Behavior (9 questions, 1-4 points), Depression/Self-perception (7 questions, 1-4 points) and Embarrassment (3 questions, 1-4 points). Since its development in the United States, the FIQL has been translated into many languages with verified reliability and validity, including two Japanese versions[141,142]. The Japanese versions allow evaluation of not only each element but also the total score (1-4.1 points). Although FIQL is extremely useful for evaluating FI-specific QoL, the number of questions is too large to be used routinely in daily clinical practice because of their complexity.

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|This questionnaire is intended to evaluate your defecation function. Please check only one box for each question. If your symptoms differ depending on the day, it may be difficult to narrow them down to a single answer; however, even in such cases, please select only one answer that best describes your usual defecation situation. Even if you have recently had an infection that may have affected your defecation function, please choose the answer that describes your usual defecation function without considering the infection.|| |---|---| |1. Do you ever have occasions when you cannot control your flatus (wind)?|| |☐ No, never|0| |☐ Yes, less than once per week|4| |☐ Yes, at least once per week|7| |2. Do you ever experience any accidental leakage of liquid stool?|| |☐ No, never|0| |☐ Yes, less than once per week|3| |☐ Yes, at least once per week|3| |3. How often do you open your bowels?|| |☐ More than 7 times per day (24 hours)|4| |☐ 4-7 times per day (24 hours)|2| |☐ 1-3 times per day (24 hours)|0| |☐ Less than once per day (24 hours)|5| |4. Do you ever have to open your bowels again within 1 hour of the last bowel opening?|| |☐ No, never|0| |☐ Yes, less than once per week|9| |☐ Yes, at least once per week|11| |5. Do you ever have such a strong urge to open your bowels that you have to rush to the toilet?|| |☐ No, never|0| |☐ Yes, less than once per week|11| |☐ Yes, at least once per week|16| |Add the scores from the five responses to calculate a final total score.|Total score: pts| |Interpretation:|| |0-20 pts: No LARS|| |21-29 pts: Minor LARS|| |30-42 pts: Major LARS||

[The Japanese version of the LARS score whose reliability and validity have been confirmed in Akizuki et al. [145]].

Therefore, in clinical studies requiring accurate evaluation of QoL, it is recommended to evaluate both the symptomatic severity of FI and FI-specific QoL using the FISI and the Japanese version of the FIQL, respectively, at the same time. Two studies reported that the MID for the FIQL was 1.1 to 1.2 points[137] and 0.7 to 1.1 points[143]. Even when the same questionnaire is used, the MID varies depending on

the participant and method of investigation[136].

In LARS, not only FI but also frequent bowel movements within a short period of time called “clustering” are often problematic; thus, the LARS Score[144], which considers LARS-specific symptoms, is more suitable than CCFIS and FISI as a scale for evaluating symptomatic severity of LARS, and its Japanese version is available with verified re-

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liability and validity (Table 10)[145]. However, the LARS score evaluates symptoms related to FI, such as gas and liquid FI, fecal urgency, and clustering, but does not evaluate evacuation difficulty and the sensation of incomplete defecation, which are sometimes problematic in LARS. In addition, the impact of LARS on QoL is not evaluated, and some reports have indicated that the LARS score does not reflect the degree of impairment in QoL[146].

Therefore, the Japanese version of the FIQL[141,142] is recommended for use to evaluate FI-specific QoL in patients with LARS, whereas the Japanese version of the EORTC QLQ-C30[147] and the Japanese version of the EORTC QLQ-CR38[148] are recommended for use to evaluate general health-related QoL, including defecation disorders. In addition, the mFIQL[149] is used to evaluate FI-specific QoL after rectal cancer surgery. However, it was developed based on the FIQL, excluding 10 questions on depression/ self-perception and embarrassment from the 29 questions in the original FIQL. Therefore, it cannot evaluate depression and embarrassment caused by FI, which are important for the QoL of patients with FI. Thus, the use of mFIQL alone is not recommended as a questionnaire to evaluate FI-specific QoL after rectal cancer surgery.

In clinical research, treatment success is commonly defined as a reduction of at least 50% in the mean number of FI episodes per week[94]. However, according to an online survey, only 58% of patients with FI accepted a reduction of at least 50% in FI frequency as the definition of treatment success, with only 26% of older adults aged ≥65 years accepting it, in particular. While many patients considered a reduction of at least 75% as the definition of treatment success, younger people and patients with severe FI tended to accept a reduction of at least 50% as the definition of treatment success[150].

Regarding the statement at the beginning, "In clinical studies, treatment success is proposed to be defined as a reduction of at least 50% in the mean number of FI episodes per week after treatment compared with that before treatment," there were opinions supporting it as a strong recommendation during the vote to determine the strength of recommendation in the Guideline Preparation Committee.

III. Examinations for Fecal Incontinence (more detailed description)

Examinations for fecal incontinence (FI) are performed to determine its causes and pathophysiology. A comprehensive diagnosis based on symptoms, medical history, physical findings, and the results of multiple tests is often required because it is difficult to determine the cause and pathophysiology accurately with a single examination. These tests include anorectal manometry, anorectal sensation tests, pudinal nerve terminal motor latency (PNTML), anal electro-

myography, ultrasonography, pelvic magnetic resonance imaging (MRI), and defecography. These tests are physically and mentally demanding on the patient; thus, careful consideration must be given when deciding on and performing the indicated tests. These examinations are described as tools for diagnosing the causes and pathophysiology of FI, although some are performed in patients with constipation.

A. Physiological examination

Among the anorectal physiology examinations, five are covered by national health insurance: anorectal manometry, rectoanal inhibitory reflex test, rectal sensation test, rectal compliance test, and simulated defecation test. The medical fee is 800 points for one of these five tests and 1,200 points for two or more tests, which can be reimbursed only once a month. Among these, simulated defecation tests, such as the rectal balloon expulsion test, are used to diagnose functional defecation disorder, which is a type of constipation. Therefore, in this section, in addition to anorectal manometry, rec-toanal inhibitory reflex test, and rectal sensation test, the PNTML and anal electromyography are described.

1. Anorectal manometry

Statement

$\bullet$ Anorectal manometry is proposed to be performed on a case-by-case basis because it can be useful for identifying the causes of fecal incontinence and guiding specialized treatment plans by objectively assessing anal sphincter function.

ansal phincter function.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

The primary measurement parameters include the functional anal canal length, resting anal pressure, and voluntary contraction pressure (measured value and incremental value). Resting anal pressure is considered to reflect the internal anal sphincter (IAS) function; however, some reports indicate that 55% of it is contributed by the IAS, 30% by the external anal sphincter (EAS), and 15% by the anal cushion. Voluntary contraction pressure reflects the EAS function; however, there are two types of voluntary contraction pressures, that is, the measured value from the atmospheric pressure and the incremental value from the resting anal pressure. The incremental value of the voluntary contraction pressure reflects the EAS function.

Low resting anal pressure indicates poor IAS function, which predisposes patients to passive fecal incontinence (FI), whereas low voluntary contraction pressure indicates poor EAS function, which predisposes patients to urge FI. Anorectal manometry can help identify the causes of FI by objectively assessing the function of the anal sphincter. However, the reference values for resting anal pressure and voluntary contraction pressure vary greatly depending on individuals and sex as well as on measurement devices and

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methods; thus, care must be taken when interpreting the measured values.

Commentary

Three measurement devices are used for this test: water perfusion system, pressure transducer catheter, and microbal-loon catheter. In the test using a catheter with a pressure measurement point only at the same level along the longitudinal axis of the catheter, it is necessary to withdraw the catheter to measure the pressure over the entire length of the anal canal. In contrast, the test using a catheter with multi-ple pressure measurement points at the same intervals along the longitudinal axis of the catheter can measure the anal canal pressure of the entire length of the canal while the catheter is stationary. This test is referred to as high-resolution anorectal manometry (HRAM)[151].

The primary measurement parameters include the length of the anal canal reflecting the anal canal pressure (functional anal canal length), anal canal pressure at rest (resting anal pressure), anal canal pressure during anal sphincter contraction (voluntary contraction pressure), and anal canal pressure during coughing (involuntary contraction pressure)[152-156]. In addition, when the anal canal pressure is measured while the rectal balloon is inflated with approximately 50 mL of air, the pressure rises sharply, then falls below the resting anal pressure, and gradually recovers to near the resting anal pressure. The increased pressure phenomenon is called the rectoanal excitatory reflex (RAER), whereas the decrease and recovery phenomenon are called the rectoanal inhibitory reflex (RAIR).

Resting anal pressure is generally considered to reflect the IAS function; however, some reports indicate that 55% of it is contributed by the IAS, 30% by the EAS, and 15% by the anal cushion[157]. Voluntary contraction pressure is generally considered to reflect the EAS function; however, there are two types of voluntary contraction pressures, namely the measured value from the atmospheric pressure and the incremental value from the resting anal pressure. The incremental value of the voluntary contraction pressure reflects the EAS function[155,156]. Involuntary contraction pressure reflects the reflex contraction of the EAS in response to an increase in intra-abdominal pressure caused by coughing[158]. The RAER is a phenomenon in which the EAS contracts reflexively in response to the expansion of the rectal wall. When the sacral and/or pudendal nerves are impaired, the involu- tary contraction pressure decreases and the RAER disap- pears[159]. RAIR is a phenomenon in which the IAS re- laxes in response to the expansion of the rectal wall and is an intramural reflex that occurs in the rectum and anus. The loss of this reflex indicates the possibility of Hirschprung's disease, but is not directly relevant to the management of FI.

According to a meta-analysis (13 papers, 2,91 patients)[160] in which anal manometry was performed on patients with FI, low resting anal pressure was found in 44%

of women and 27% of men, whereas low contraction pressure was found in 69% of women and 36% of men. Low resting anal pressure indicates poor IAS function, which predisposes to passive FI[161], whereas low voluntary contraction pressure indicates poor EAS function, which predisposes to urge FI[59,162]. In a prospective study[163] that investigated the influence of anorectal physiology tests on decision-making for the treatment of FI, 45 out of 90 patients with FI were planned for conservative therapy, whereas the remaining 45 were planned for surgical treatment in the pre-examination meeting by an expert team. However, after review based on the results of anal manomer, PNTML, and endoanal ultrasonography, 5 (11%) of the 45 patients scheduled for conservative therapy were changed to surgical treatment, whereas 4 (9%) of the 45 patients scheduled for surgical treatment were changed to conservative therapy. Although endoanal ultrasonography results were more influential, it was demonstrated that anorectal matrometry also influenced the decision-making for the treatment of FI, as the examination results were assessed comprehensively.

Although the usefulness of anorectal manometry in the management of FI is controversial [164,165], it may be useful for identifying the causes of FI and guiding specialized treatment plans by objectively assessing anal sphincter func-tion; thus, it is recommended to be performed on a case-by-case basis [69,94,166]. However, because the reference val-ues for resting anal pressure and voluntary contraction pres-sure vary greatly depending on individuals and sex [167] as well as on measurement devices and methods [168], care must be taken when interpreting the measured values. There-fore, anorectal manometry is weakly recommended to be performed on a case-by-case basis to identify the causes of FI and to guide specialized treatment plans by the European Guideline [69], as an expert opinion, and the ASCRS Clin-ical Practice Guidelines [94], with a very low level of evi-dence.

2. Anorectal sensation tests

The rectal balloon sensation test, which assesses the sen-sation of pressure on the rectal wall by balloon distension, and the anal mucosal electrosensitivity test, which assesses the sensation of electrical stimulation on the anal mucosa, are performed as objective assessments of anorectal sensa-tion.

a. Rectal balloon sensation test

Statement

$\bullet$ Rectal balloon sensation test is proposed to be performed on a case-by-case basis because it can be useful for identifying the causes of fecal incontinence and guiding specialized treatment plans by objectively assessing rectal hypersensitivity and hyposensitivity.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

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Abstract

In patients with irritable bowel syndrome or other disorders associated with urge fecal incontinence (FI) due to rectal hypersensitivity, diagnosis using the rectal balloon sensation test can help determine indications for normalization training of the rectal sensation, which is part of biofeedback therapy. Conversely, in patients with overflow passive FI associated with fecal impaction due to rectal hyposensitivity, diagnosis using the rectal balloon sensation test can help determine indications test can help determine indication test should be interpreted with caution because they are influenced by not only rectal sensation but also rectal capacity and compliance.

Although the anal mucosal electrosensitivity test is occasionally used in research, it is rarely employed in daily clinical practice.

Commentary

a. Rectal balloon sensation test

This test assesses the sensation of pressure on the rectal wall by gradually inflating a balloon inserted into the rec- tum with air to measure the following three val- ues[152,156,169,170]:

$\bullet$ First sensation volume (FSV): The minimum volume at which the subject first feels a change in the inflated balloon, also referred to as the rectal threshold volume. $\bullet$ Urge volume (UV): The minimum volume that induces an urge to use the toilet for defecation.

* Maximum tolerable volume (MTV): The maximum volume the subject can tolerate.

The London classification by the International Anorectal Physiology Working Group (IAPWG)[154] recommends di-agnosing patients with rectal hypersensitivity if one or more of the three measurement items of FSV, UV, and MTV are below the reference value, while it recommends diagnosing patients with rectal hypersensitivity if two or more items are above the reference value. According to a meta-analysis of studies involving patients with FI (13 studies, 2,981 cases)[160], rectal hypersensitivity was observed in 10% of women and 4% of men, whereas rectal hyposensitivity was noted in 7% of women and 19% of men.

Rectal hypersensitivity can cause fecal urgency, urge FI, and frequent bowel movements[35] and is often observed in patients with diarrhea-predominant IBS[171,172] in addition to radiation proctitis and ulcerative colitis. Thus, this test is useful for evaluating rectal sensitivity in these conditions[152,173]. According to Chan et al.[35], 44% of patients with FI had rectal hypersensitivity, and these patients defecated significantly more frequently and had significantly more restricted daily activities than those with normal rectal sensitivity. In addition, rectal hypersensitivity is frequently observed in patients with diarrhea-predominant IBS[171] and is correlated with its symptomatic severity[172]. Fur-

thermore, this test is also useful for evaluating the capacity of the neorectum after rectal resection[174], as its results reflect not only rectal sensation but also rectal capacity and compliance. Improvement of FI symptoms by biofeedback therapy[175] or drug therapy[176] is reported to be correlated with improvement in rectal hypersensitivity. In contrast, the test results may not change significantly even if the FI symptoms improve; thus, interpretation of the test results may be difficult in some cases[152].

Rectal hyposensitivity can cause constipation[177] and/or overflow passive FI[35,178,179] associated with rectal fecal impaction due to difficulty in feeling the urge to defecate. This condition is often observed in patients with spinal cord impairment or older adults. Burgell et al.[80] found that 26 (16%) of 160 male patients with FI had rectal hyposensitivity, and the prevalence of constipation symptoms was significantly higher in the rectal hyposensitivity group than in the normal rectal sensitivity group. When rectal fecal impaction due to weakening or loss of the urge to defecate, associated with rectal hyposensitivity, is diagnosed as the cause of overflow passive FI, the FI symptoms may be improved by bowel habit training and normalization training of the rectal sensation using a rectal balloon[180].

As described above, evaluation of abnormal rectal sensitivity by this test can elucidate the pathophysiology and causes of FI[181], which may be useful for guiding treatment plans, and may improve FI symptoms through normalization of rectal sensitivity[69,197,182]. However, care must be taken when interpreting the test results because they are influenced not only by rectal sensation but also by rectal capacity and compliance. In addition, reference values should be established for each facility because the test results differ depending on the shape and compliance of the balloon used and the test method, including the balloon inflation speed[183]. Furthermore, although extremely rare, there have been reports of rectal perforation in patients who underwent this test after rectal resection surgery[184]; thus, extra caution is required in determining the indications and performing this test in patients who underwent rectal resection surgery.

b. Anal mucosal electrosensitivity test

This test assesses the anal mucosal electrosensitivity threshold at which the patient complains of stimulation sensation by gradually increasing the intensity of electrical stimulation to the anal mucosa after a catheter attached to the stimulation electrode is inserted into the anal canal.

A diagnosis of anal hyposensitivity is made when the threshold value is greater than the upper limit of the reference value[185], although reference values differ depending on the stimulator. This test is occasionally used in research but is rarely employed in daily clinical practice.

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3. Pudendal nerve terminal motor latency

Abstract

This test is used to evaluate the presence or absence of pudendal neuropathy. Patients with fecal incontinence (FI) may have prolonged PNTML compared with those without FI (control group). This test is of little use for the management of FI because its results depend on the examiner's technique, and it has low reliability for evaluating pudendal neuropathy.

Commentary

In the PNTML test, an electrical stimulation electrode attached to the tip of the index finger of a glove is inserted into the rectum to electrically stimulate the pudendal nerve through the rectal wall near the ischial tuberosity. The contraction of the external anal sphincter caused by stimulation is detected by a receiving electrode attached to the base of the index finger in the anal canal (Figure 4)[186].

The time from the electrical stimulation of the pudendal nerve to the contraction of the external anal sphincter is the PNTML, which is measured separately for the left and right sides to evaluate the presence or absence of pudendal neuropathy. In other words, when the PNTML is prolonged, a diagnosis of pudendal neuropathy is made [187]. St. Mark's electrode is often used as the electrode for this test, and although the cutoff value of the conduction time varies slightly by institution, a diagnosis of pudendal neuropathy is often made when the PNTML is ≥2.2 ms [188,189] or 2.4 ms [188,190]. Although this test has been used historically for the management of FI [187,191], it is of low reliability as a test to evaluate pudendal neuropathy because its results are dependent on the examiner's technique and because it reflects only damage to nerve fibers with the fastest conduction velocity and cannot evaluate damage to nerve fibers with slower conduction velocity [192]. Therefore, its usefulness and strength of recommendation for managing FI is currently considered to be low [152,193]. The ASCRS Clinical Practice Guidelines [94] strongly recommend that this test should not be performed as a standard examination with a low level of evidence.

4. Anal electromyography

Abstract

This test evaluates the contractility and relaxation state of the external anal sphincter and the puborectalis muscle by measuring their electrical activities. Three types of electrodes are used for the test: needle electrodes inserted into the anal sphincters, surface electrodes applied around the anus, and anal electrodes inserted into the anal canal. Anal electromyography using the surface electrode or anal electrode has been used to diagnose the causes of fecal inconti- nence (FI); however, currently, it is often used as a therapeutic device to provide feedback to patients on the degree of anal sphincter contraction in biofeedback therapy for FI. Needle electrodes are mainly used in research due to the pain associated with needle insertion.

Commentary

This test evaluates the contraction and relaxation states of the external anal sphincter and the puborectal muscle by measuring their electrical activities. Three types of electrodes are used for the test: needle electrodes inserted into the anal sphincters, surface electrodes applied around the anus, and anal electrodes inserted into the anal canal [194,195]. With the needle electrode, the patient undergoes examination in the lateral position, and the site and degree of disruption of the anal sphincters can be diagnosed by evaluating the motor unit potential (MUP: electrical activity with a certain voltage and width), which is the electrical activity level of the anal sphincters, at each site [152]. However, this approach is currently superseded by endoanal ultrasonography for the diagnosis of the site and degree of disruption [196]. Because of the pain associated with needle electrode insertion, anal electromyography using a needle electrode is rarely performed in daily clinical practice and is mainly used for research [194]. With the surface electrode and anal electrode, the patient can undergo examination either in the lateral or sitting position; however, in general, they only allow the evaluation of the contraction and relaxation states of the entire anal sphincter and cannot be used to evaluate the electrical activity level of the anal sphincters at each site. Recently, however, high-resolution anal electrodes with many electrodes have been developed [197]. Although they allow the evaluation of the contraction and relaxation states of the anal sphincters at each site without insertion of the needle electrode, they are still in the research stage.

Although anal electromyography has been used to diagnose the causes of FI[198,199], it is now often used as a therapeutic device to provide feedback to patients on the degree of anal sphincter contraction in biofeedback therapy for FI[152,200]. In addition, it is used to diagnose pelvic floor incoordination, in which the external anal sphincter and puborectal muscle, which should normally remain relaxed, contract during straining for defecation[201]. Moreover, it is used in biofeedback therapy for functional defecation disfor-

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der caused by pelvic floor incoordination, which is one of the causes of constipation[200,202].

B. Morphological examination

1. Ultrasonography

Statement

$\bullet$ Because endoanal ultrasonography is useful for diagnosing anal sphincter injury, it is proposed to be used for identifying the causes of fecal incontinence.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ Although endovaginal ultrasonography and transperineal ultrasonography can visualize puborectalis muscle injury and pelvic organs, their diagnostic accuracy for anal sphincter injury is lower than that of endoanal ultrasonography. Thus, they are proposed to be used in situations where endoanal ultrasonography is not available.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

Endoanal ultrasonography is a minimally invasive and simple examination method that requires the use of a dedicated probe, and it is useful for diagnosing internal and external anal sphincter injuries, tears, scarring, and atrophy, as well as for measuring the thickness of the anal sphincters. It has been reported that the incidence of fecal incontinence (FI) in obstetric anal sphincter injuries (OASIS) increases with the severity of the anal sphincter injury diagnosed by ultrasonography. In addition, it has also been reported that OASIS was diagnosed in 30% of women with anal incontinence who underwent endoanal ultrasonography, although not clinically diagnosed with OASIS at the time of vaginal delivery. Therefore, endoanal ultrasonography is the most useful examination method for diagnosing OASIS. Thus, we propose using it for diagnosing the pathophysiology and causes of FI.

Endovaginal ultrasonography can be performed with a probe used in obstetrics and gynecology and is superior to endoanal ultrasonography in the visualization of puborectalis muscle injury and pelvic floor opening formed by the levator ani, called the levator hiatus, which are difficult to diagnose by endoanal ultrasonography. However, its diagnostic accuracy for OASIS is lower than that of endoanal ultrasonography.

Transperineal ultrasonography can be performed using a versatile convex-type probe, and it allows for the visualization of the anal canal and a wide range of pelvic organs. In addition, it can evaluate still images, evaluate pelvic floor muscle contraction, and diagnose pelvic floor organ prolapse during straining. The use of a dedicated probe capable of 3 D/4D construction allows for the diagnosis of injuries to the anal sphincters and puborectalis muscle, and it has been re-

ported that its diagnostic accuracy for OASIS is comparable to that of endoanal ultrasonography.

Based on the above, endoanal ultrasonography is most recommended for the diagnosis of anal sphincter injuries, including OASIS. However, in facilities where such test equipment is not available, we propose diagnosing them with endovaginal or transperineal ultrasonography, although their diagnostic accuracy is lower.

Commentary

a. Endoanal ultrasonography

In endoanal ultrasonography, a dedicated radial or linear probe is inserted into the anus to visualize and evaluate the morphology of the internal and external anal sphincters by ultrasound. The patient is positioned in the prone or lithotomy position during examination to avoid left-right differences, but the test is often performed in the supine position to avoid embarrassment. In the ultrasound images, the internal anal sphincter is visualized as a uniformly concentric hypoechoic area, whereas the external anal sphincter is visualized as a medium- to hyperechoic area on the outside[203], and different structures are visualized depending on the height of the anal canal (Figure 5). Starting from the cranial side, at the upper level, the concentric deep external anal sphincter and the U-shaped puborectalis muscle are visualized as a hyperechoic area on the outside of the internal anal sphincter. At longitudinal muscle, is visualized as a medium-echoic area on the outside of the hypoechoic internal anal sphincter. At the lower level, only the subcutaneous external anal sphincter is visualized as a hyperechoic ring, whereas the internal anal sphincter is not visualized at this level. These differences in echo images that vary depending on the height of the canal canal are important for lesion orientation.

This test is used to diagnose anal sphincter injury, laceration (a condition in which the anal sphincters remain cut with no signs of repair), scarring, atrophy, and to evaluate the morphology of the anal sphincters by measuring the thickness of the anal sphincters. Injuries to the external anal sphincter can be diagnosed by the depiction of hypoechoic areas in the hyperechoic area, whereas injuries to the internal anal sphincter can be diagnosed by the depiction of hyperechoic areas in the hypoechoic area. Once the examiner is skilled in the test, there should be no significant difference in diagnosis between examiners, making this test highly accurate[204]. It has been reported that the prevalence of severe FI was 20 times higher in patients diagnosed with external anal sphincter injury by this test than in patients diagnosed having such injury[205].

In particular, this test is considered the most useful test for diagnosing OASIS[206,207]. The guideline published by the Royal College of Obstetricians and Gynaecologists[208] recommends classifying third-degree perineal lacerations

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 Figure 5. Normal images of endoanal ultrasonography.

A: upper level, B: middle level, C: lower level.

IS: internal anal sphincter, ES: external anal sphincter, PM: puborectal muscle

Table 11. Classification of Obstetric Perineal Lacerations.

|First degree|Injury extending to the vaginal mucosa or perineal skin| |---|---| |Second degree|Injury extending to the perineal muscles (bulbospongiosus and superficial transverse perineal muscles)| |Third degree|Injury extending to the anal sphincters| |3a|Injury that is less than 50% of the thickness of the external anal sphincter| |3b|Injury extending to more than 50% of the thickness of the external anal sphincter| |3c|Injury extending to the internal anal sphincter| |Fourth degree|Injury extending to the anal epithelium and rectal mucosa|

Among perineal lacerations (first to fourth degree), obstetric anal sphincter injuries during childbirth fall into the third- and fourth-degree categories [208].

(lacerations with injury extending to the anal sphincters) into 3a (injury that is less than 50% of the thickness of the external anal sphincter), 3b (injury extending to more than 50% of the thickness of the external anal sphincter) but not extending to the internal anal sphincter), and 3c (injury to both internal and external anal sphincters). Based on their experience with 1,892 OASIS cases, Wan et al.[209] reported that, compared with patients with OASIS grade 3a, patients with OASIS grade 3b or above had a higher incidence of FI, lower anal pressure, persistent anal sphincter defects in endoanal ultrasonography, a higher incidence of fistula formation, and a higher need for anal sphincter resunting. In addition, Johannessen et al.[210] found that patients with OASIS grade 3c and 4 were at a higher risk of developing FI than patients with OASIS grade 3b and below (Table 11: OASIS).

Wan et al.[209] performed this test on 134 patients with anal incontinence despite no clinical diagnosis of OASIS after childbirth and found OASIS in 40 patients (30%). A meta-analysis of studies evaluating the relationship between anal incontinence and the diagnosis of OASIS by ultra-sonography (103 papers, 16,110 cases)[211] showed that 26% of women post vaginal delivery were diagnosed with OASIS by ultrasonography, and the prevalence of anal in-

continence was 19%. In addition, among 3,688 patients not clinically suspected of OASIS, 13% were diagnosed with OASIS by ultrasonography, and the prevalence of anal continence was 14%. Furthermore, of 7,549 patients who had undergone anal sphincter repair for OASIS, 55% had residual anal sphincter defects on ultrasonography, and the prevalence of anal incontinence was 38%. Compared with patients without OASIS on ultrasonography, the prevalence of anal incontinence was significantly higher (3.74 times) in patients diagnosed with OASIS. Therefore, the meta-analysis has demonstrated the importance of using ultrasonography to diagnose the presence or absence of OASIS in patients not clinically diagnosed with OASIS. In addition, this test is useful for evaluating the degree of repair after anal sphincter repair or sphincteroplasty for OASIS[212]. Furthermore, even if FI does not develop immediately after vaginal delivery, it may develop due to OASIS after the age of 40 years, and this test is useful for diagnosing this condition[213,214].

This test is also useful for diagnosing internal anal sphincter injury and atrophy. Passive FI associated with internal anal sphincter injury may occur after lateral internal anal sphincterotomy for anal fissures, after radical anal Fis-tula treatment, or in rare cases, after ligation and resection of internal hemorrhoids, and this test is useful for diagnos-

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ing these conditions[215]. In addition, the internal anal sphincter thickens with age, and the 95% confidence interval of the thickness of the internal anal sphincter in healthy individuals has been reported to be 2.4-2.7 mm for those under 55 years of age and 2.8-3.4 mm for those over 55 years of age[216]. Internal anal sphincter degeneration has been reported as a condition in which the internal anal sphincter atrophies[161]. It is characterized by passive FI as the main complaint, with low maximum resting pressure (<40 cmH₂O) and thinning of the internal anal sphincter (<2 mm in thickness), and this test is useful for diagnosing this condition.

b. Endovaginal ultrasonography

Endovaginal ultrasonography uses either a linear or radial probe, as in endoanal ultrasonography, but probes commonly used in obstetrics and gynecology can be used. In the lithotomy position, a probe is inserted into the vagina, and 3 D images are constructed to evaluate the pelvic floor structure. The images are divided into four sections based on the height in the axial plain, and starting from the cranial side, the bladder area and rectum can be visualized and evaluated at level I, the bladder neck, urethra and anorectal angle at level II, the urethra and puborectalis muscle at level III, and the perineal muscles, such as the superficial transverse perineal muscles, and the middle-lower anal canal at level IV[217] (Figure 6).

Endovaginal ultrasonography is excellent for visualizing the puborectalis muscle and levator hiatus. Puborectalis muscle injury is observed in 13%-36% of primiparas who have had a vaginal delivery[218]. However, it is difficult to diagnose puborectalis muscle injury by endoanal ultrasonography. In addition, injury to the pubovisceral muscle (a muscle group combining the puborectalis and pubococcygeus muscles) and dilation of the levator hiatus, diagnosed by endovaginal ultrasonography, are associated with the severity of FI[205]. Therefore, although endovaginal ultrasonography is useful for visualizing the puborectalis muscle and levator hiatus, it is inferior to endoanal ultrasonography in the visualization of the anal sphincters themselves and the diagnosis of anal sphincter injury, which are the most important factors in the diagnosis of OASIS[207].

c. Transperineal ultrasonography

Transperineal ultrasonography uses a versatile convex-type probe, which is also used in abdominal ultrasonography, to scan the perineum from the pubic bone to the anus in the lithotomy position to visualize and evaluate pelvic organs (bladder, urethra, vaginal wall, anal canal, and rectum) and pelvic floor muscles, such as the puborectalis muscles, in the midsagittal section[219] (Figure 7). It allows the evaluation of static images as well as the evaluation of pelvic floor muscle contraction and the observation of pelvic floor organ prolapse (cystocele, uterine prolapse, rectocele, and enterocele) during the Valsalva maneuver. Its diagnostic

 Figure 6. Normal image of endovaginal ultrasonography. Within dotted line: Levator hiatus.

P: pubic bone, U: urethra, R: rectum, PR: puborectal muscle.

 Figure 7. Normal image of transperineal ultrasonography. A: anal canal, V: vagina, U: urethra, B: bladder.

accuracy for rectocele, enterocele, rectal intussusception, and rectal prolapse was superior to that of defecography[220].

The use of a dedicated probe capable of 3D construction or 4D construction, including the time axis, allows for the diagnosis of injuries to the anal sphincters and puborectalis muscle through the construction of axial tomographic images. In the visualization of the anal sphincters themselves and in the diagnosis of anal sphincter injury, which are the most important factors for diagnosing OASIS, transperineal ultrasonography has been reported to be inferior to endoanal ultrasonography [207], whereas another report has stated that transperineal ultrasonography using a 3D/4D probe is not in-

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ferior to endoanal ultrasonography[221]. Therefore, the choice of whether to perform endoanal or transperineal ultrasonography for diagnosing OASIS depends on the skill and preference of the examiner and the availability of the examination equipment. Although endoanal ultrasonography requires a dedicated probe, it is relatively easy to master because it provides easy anatomic orientation. In contrast, while transperineal ultrasonography itself can be performed with a versatile abdominal ultrasound probe, it can achieve the same diagnostic accuracy for OASIS as endoanal ultra-sonography if a dedicated 3D/4D probe is used, but it is relatively difficult to master, as anatomic orientation is difficult.

2. Pelvic MRI

Statement

* Anal MRI is proposed to be performed for identifying the causes of fecal incontinence because it is useful for evaluating the presence or absence and the degree of disruption or atrophy of the anal spinsters and pelvic floor muscles.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

Pelvic MRI performed for the management of fecal incontinence (FI) includes anal MRI and MRI defecography. There are two types of anal MRI, namely endoanal MRI, which is performed by placing a dedicated endoanal coil in the anal canal, and external phased-array MRI, which is performed by placing a coil on the body surface. However, in Japan, only external phased-array MRI can be performed because the endoanal coil is yet to be approved. Anal MRI can evaluate the presence or absence of disruption or atrophy of the anal sphincters and pelvic floor muscles by imaging the structure of these muscles.

MRI defecography has an advantage over conventional fluoroscopic defecography in that it allows the evaluation of the condition of other pelvic organs, such as the uterus and bladder, while avoiding radiation exposure. However, it has a disadvantage in that it is more nonphysiological because the patient is required to expel artificial stool in the supine position. Because of the nonphysiological posture for artificial stool expulsion, sufficient straining cannot be achieved. Thus, the diagnostic accuracy of this test is lower than that of fluoroscopic defecography in diagnosing rectal intussusception or rectocele, which may cause FI.

Commentary

Pelvic MRI is a diagnostic imaging technique that uses nuclear magnetic resonance to assess pelvic organs, pelvic floor muscles, and anal sphincters. MRI used for the management of FI includes an anal MRI, which evaluates with static images, and MRI defecography, which evaluates the dynamic state[222]. An international consensus has been reached on the terminology related to MRI and the interpre-

tation of MRI images in the evaluation of pelvic floor dys- function, including FI[223,224].

There are two types of anal MRI, namely endoanal MRI, which is performed by placing a dedicated endoanal coil in the anal canal, and external phased-array MRI, which is performed by placing a coil on the body surface. In Japan, however, only external phased-array MRI can be performed because the endoanal coil is yet to be approved. In general, endoanal MRI is considered to have higher resolution and diagnostic accuracy than external phased-array MRI, although a study reported that there was no difference between the two [225]. Anal MRI can evaluate the presence or absence of disruption or atrophy of the anal sphincters and pelvic floor muscles by imaging the structure of these muscles [226]. On T2-weighted images, ligaments and fascia are visualized as low signals, the EAS is visualized as relatively low signals, and fat and the internal anal sphincter (IAS) are visualized as high signals. In general, endoanal ultrasonography is more useful for the diagnosis of disruption or atrophy of the IAS than for the diagnosis of the EAS, whereas endoanal MRI is considered more useful for the diagnosis of disruption or atrophy of the EAS than for the diagnosis of the IAS [227]. However, it has been reported that there is no difference between the two in the diagnostic accuracy of anal sphincter disruption, with their sensitivity and positive predictive value for anal sphincter disruption diagnosed by intraoperative findings being 90% and 85% by endoanal ultrasonography and 81% and 89% by endoanal MRI, respectively [228].

MRI defecography is an examination in which videos are recorded while the artificial stool injected into the rectum is expelled. In the management of FI, it is performed to diagnose rectal intussusception and rectocele, which are considered possible causes of FI[222,229]. This test has an advantage over conventional fluoroscopic defecography in that it allows the evaluation of the condition of other pelvic organs, such as the uterus and bladder, while avoiding radiation exposure. The disadvantage of this approach is that the patient is required to expel artificial stool in the supine position, making it more nonphysiological than fluoroscopic defecography, which is performed in the sitting position. Although MRI defecography that can be performed in the sitting position is also available, it is not widely used because it requires special MRI equipment[230]. In addition, according to a meta-analysis, the diagnostic accuracy of MRI defecography for rectal intussusception or rectocele is lower than that of fluoroscopic defecography, as sufficient straining cannot be achieved because of the nonphysiological posture for artificial stool expulsion[231]. Therefore, this test is considered less useful for diagnosing the causes of FI than fluoroscopic defecography.

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3. Defecography

Statement

$\bullet$ Defecography is useful for diagnosing rectal intussception and rectocele, which can cause fecal incontinence. Thus, it is proposed to be performed on a case-by-case basis.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

Defecography (evacuation proctography) allows the evaluation of anorectal angle, perineal descent, anal sphincter contractility, ability to expel artificial stool, and dynamics of the pelvic floor muscles and rectum during artificial stool expulsion. In addition, it allows the diagnosis of the presence or absence as well as the degree of rectocele, rectal intussception, sigmoidocele, and enterocele. However, caution is required when interpreting the results, as these conditions can also be observed in healthy individuals without defecation disorders.

Obtuse anorectal angle and excessive perineal descent are believed to be involved in the weakening of pelvic floor muscles, which may cause fecal incontinence (FI). However, it is impossible to evaluate the presence or absence as well as the degree of FI by these factors alone, as there are large individual differences even among healthy individuals. In addition, this test also allows the evaluation of anal sphincter contractility by assessing the ability to hold artificial stool in the rectum during the injection of artificial stool into the rectum and in the sitting position after the injection.

In patients with FI who do not achieve adequate improvement with maximal conservative therapies, FI can be improved by ventral rectopexy if severe rectal intussusception or rectocele is found by defecography. Therefore, it is recommended to perform defecography on such patients.

Commentary

Defecography is an examination to evaluate the morphology and dynamics of the rectum and pelvic floor muscle group during defecation. Although its examination methods vary from institution to institution, recently, the ASCRS, in collaboration with five other international societies, has published a consensus on examination method and image interpretation[232]. The general examination method involves injecting a mixture of contrast agent and a material for maintaining viscosity (artificial stool) into the rectum, placing the patient in the sitting position, and taking still and video X-ray images from the side and the front at rest during anal sphincter contraction and defecation. In some cases, barium or gastrografin is administered 30-120 minutes before the examination to simultaneously contrast the small intestine, or barium is injected before the injection of artificial stool to contrast the sigmoid colon. This examination allows the evaluation of the anorectal angle, perineal descent, anal sphincter contractility, ability to expel artificial stool, and

dynamics of the pelvic floor muscles and rectum during artificial stool expulsion [233]. In addition, it also allows the diagnosis of the presence or absence, as well as the degree of rectocele, rectal intussusception, sigmoidocele, and enterocele. However, caution is required when interpreting the results, as these conditions can also be observed in healthy individuals without defecation disorders [234,235].

Obtuse anorectal angle and excessive perineal descent are believed to be involved in the weakening of pelvic floor muscles, including the puborectalis muscle, which may cause FI[232]. The anorectal angle is reported to be significantly more obtuse in patients with FI than in individuals without FI (a mean of 105° vs. 116° at rest)[236]. However, it is impossible to evaluate the presence or absence as well as the degree of FI by these factors alone, as the anorectal angle and perineal descent vary substantially among individuals, even among healthy individuals. In addition, this test also allows the evaluation of anal sphincter contractility by assessing the ability to hold artificial stool in the rectum during the injection of artificial stool into the rectum and in the sitting position after the injection[237]. Furthermore, by performing this test using artificial stool containing gastro-grafin to evaluate the ability to hold artificial stool before closing the temporary stoma created at the time of rectal re-section, the state of fecal continence when the temporary stoma is closed can be predicted[238].

This test is mainly used for diagnosing defecation disorder, which is a form of constipation. However, because the usefulness of ventral rectopexy (VR) for FI associated with rectal intussusception or rectocele was reported[239], this test has also been used in the treatment of FI[240]. The mechanism by which rectal intussusception causes FI is unclear, but possible mechanisms include induction of the rec-toanal inhibitory reflex[241] and a decrease in resting anal canal pressure[242]. Collinson et al.[243] proposed the Oxford classification (grades I to V) to categorize the severity of rectal intussusception using this test and reported that this test performed on 40 patients in whom the cause of FI could not be diagnosed by rectoanal function tests or endoanal ul-trasonography revealed rectal intussusception in 63% of the patients. Hawkins et al.[61] performed this test on 147 pa-tients with FI and reported that the more severe the rectal intussusception, the more severe the FI. In addition, Tsunoda et al.[244] also reported that the degree of descent of the anterior wall in rectal intussusception was significantly correlated with the severity of FI. Furthermore, a systematic review of the outcomes of VR for rectal intussusception (10 studies, 1,147 patients)[239] found that FI improved in 62.5% of patients, and the symptom recurrence rate was 7.3%. In other words, in patients with FI who do not achieve adequate improvement with maximal conservative therapies, FI may be improved by VR if severe rectal intussusception (grade III [presenting part reaching the upper

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edge of the anal canal] and grade IV [presenting part inside the anal canal] according to the Oxford classification) is found by defecography. Therefore, it is recommended to perform defecography on such patients.

The mechanism by which rectocele causes FI is also unclear, but a possible mechanism is that stool that is not completely expelled during defecation and remains in the rectocele leaks out after defecation [243]. Formijne et al. [245] performed VR on patients with rectocele and anterocele and reported that the percentage of patients with FI was significantly reduced from 63% to 18%. In contrast, Wong et al. [246] performed VR on 84 patients with rectocele and reported significant improvement in vaginal discomfort and symptoms of defecation disorder but no improvement in FI. In addition, Tsunoda et al. [247] performed transanal repair in 30 patients with rectocele and reported that FI improved in 3 of 5 patients (60%) with FI before surgery; however, 4 of 25 patients (16%) without FI before surgery developed FI. Therefore, in the treatment of FI, defecography appears to be less significant in the diagnosis of rectocele than in that of rectal intussusception.

IV. Conservative Therapies for Fecal Incontinence

Conservative therapies for fecal incontinence (FI) include dietary therapy, bowel habit instructions, drug therapy, pelvic floor muscle training (PFMT), biofeedback therapy, and transanal irrigation. The main goals are to solidify stool consistency, increase the contractility of pelvic floor muscles including the external anal sphincter, normalize rectal sensation, and periodically empty the rectum and colon.

Among these interventions, dietary therapy, bowel habit instructions, and drug therapy can be provided with some degree of knowledge and experience and should be actively performed as initial conservative therapies even at medical institutions that do not specialize in defecation disorders. In contrast, PFMT, biofeedback therapy, and transanal irrigation require patient education and instructions based on expert knowledge and experience. Thus, they are best performed as specialized conservative therapies at institutions that specialize in defecation disorders.

The package insert of the nerve stimulation device used for sacral neuromodulation, which has been covered by insurance in Japan since 2014, explicitly states that this therapy is indicated for “patients who have failed or are not suitable for conservative therapies”. In addition, the calculation criteria for the home transanal self-irrigation instructions and management fee for transanal irrigation, which has been covered by insurance since 2018, specify that this therapy is indicated for “patients with defecation disorders caused by spinal cord injury (excluding patients after rectal surgery) who do not achieve adequate improvement even with conservative therapies for 3 months or longer”. Thus,

conservative therapies should be attempted first for FI caused by benign conditions. For various conservative therapies to be appropriately selected and implemented in Japan, the characteristics of each therapy must be well understood. This section provides an overview and explanation of each therapy.

A. Initial conservative therapy

1. Dietary therapy

Statement

* Dietary fiber intake is recommended in treating fecal incontinence associated with soft stools.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ For fecal incontinence accompanied by loose stools, it is recommended to avoid alcohol consumption and foods that soften the stool.

Strength of Recommendation: Weak (Consensus Rate: 81.8%), Level of Evidence: C

Abstract

Because fecal incontinence (FI) is more likely to occur with increased defecation frequency and softer stools, we aim to optimize stool consistency and defecation frequency by assessing food intake and indulgences that affect defecation as well as planning and instructing an appropriate die-tary therapy appropriate for each patient.

Commentary

Although there is little evidence on the usefulness of dietary therapy for FI, some randomized controlled trials (RCTs) indicate that dietary fiber supplements, such as psyl- lium, alleviate FI by improving stool consistency [248,249]. An RCT found that dietary fiber intake, in addition to the intake of antidiarrheals, such as loperamide, improved FI[250]. According to a prospective observational study that followed approximately 60,000 older women over a long pe- period, the group with the highest dietary fiber intake (25 g/ day) had a 31% lower risk of watery stools and an 18% lower risk of FI than those in the group with the lowest die- tary fiber intake (13.5 g/day)[251].

Foods rich in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) can cause diar- rhea and the urge to defecate. Thus, a low-FODMAP diet is considered effective for improving FI with soft stools [252]. In an RCT comparing the effects of a low-FODMAP diet and psyllium on FI, the frequency of FI was reduced by more than 50% in 38.9% and 50% of patients, respectively, with no statistically significant difference between the two groups [252]. In contrast, in an RCT in which older stroke patients with reduced physical strength were instructed to modify their diet and fluid intake to regulate defecation, the frequency of defecation was optimized, but FI was not re-duced [253].

Patients are advised to avoid caffeine, citrus fruits, spicy

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foods, and foods high in fat, as these have the effect of softening the stool. Limiting alcohol intake may also be effective[254]. A study reported that the symptoms of FI (evaluated by the FISI) and FI-specific QoL (evaluated by the FIQL) were significantly improved when patients with FI were instructed to consume more white rice than bread or noodles and to limit the consumption of fruits, sweets, milk, yogurt, fat, caffeinated drinks, and alcoholic drinks[255]. Although white rice contains little dietary fiber, nondigestible starch (resistant starch), which is abundant in white rice, exhibits the same physiological activity as soluble and insoluble dietary fiber in the intestinal tract[255].

Regarding the statement at the beginning, "For FI with soft stools, we recommend refraining from consuming alcohol and foods that soften stool consistency," there were opinions in favor of recommending it as a strong recommendation in the vote to determine the strength of recommendation among the Guideline Preparation Committee.

2. Bowel habit instructions

Statement

$\bullet$ The acquisition of bowel habits through appropriate instructions is recommended to be included in the treatment of fecal incontinence.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: C

Abstract

Continued accumulation of feces in the rectum is likely to cause fecal incontinence (FI). Thus, patients should defecate promptly without holding back as soon as they feel the urge to defecate. In addition, in conditions where patients do not feel the urge to defecate because of spinal cord injury or other causes, they should empty the rectum periodically by bowel habit training, in which patients attempt to defecate regularly even when they do not feel the urge to defecate.

Commentary

Bowel habit instructions are an important component of FI treatment. Patients with normal rectal sensation should be encouraged to go to the toilet promptly without holding back as soon as they feel the urge to defecate. Meanwhile, in patients with rectal hyposensation, emptying the rectum through planned defecation involving planned attempts to defecate even when no urge to defecate is felt can significantly improve FI[256,257]. In older adults and patients with spinal cord injury, if feces continue to accumulate in the rectum and no urge to defecate is felt even if there is feces in the rectum, rectal fecal impaction may occur, resulting in overflow passive FI. These patients may benefit from bowel habit training, wherein they go to the toilet twice a day (30 minutes after breakfast and dinner) to defecate even if they do not feel the urge to defecate (abdominal pressure defecation). Nurse-led education and advice on bowel habits can alleviate FI[257].

In contrast, in an RCT of 112 patients with FI admitted to

a nursing home, dietary and exercise instructions, as well as bowel habit instructions including toilet assistance, significantly increased food and fluid intake, physical activity, and frequency of defecation but did not decrease the frequency of FI[258]. In addition, Ouslander et al.[259] applied a urinary incontinence treatment method called “promoted voiding” to patients with FI in a nursing home and found that the frequency of normal bowel movements increased significantly, although the frequency of FI did not decrease significantly. The authors suggest that encouraging patients to urinate and defecate, according to their own will, can prevent constipation and fecal impaction by increasing toilet mobility and fluid intake, and they highlight the need for comprehensive behavioral therapy specifically tailored to treat FI.

3. Care for fecal incontinence

Statement

$\bullet$ For prevention and treatment of fecal IAD, it is recommended to gently wipe or clean the skin with products other than soap (alkaline) and to keep it moisturized with a moisturizer.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: A

Abstract

Important care for patients with refractory fecal incontinence (FI) includes planned defecation through bowel habit instructions, the use of pads and diapers, and prevention and care for IAD. Because the care varies substantially among individuals depending on the state of FI and age, it is important to provide care based on a thorough assessment of the condition of each patient.

Commentary

Care must be provided to patients with refractory FI such that FI does not become a social or hygienic problem in daily life. In nursing homes, the most common care for older adults with FI is the use of pads and diapers (88.9%), followed by planned defecation (38.6%)[260]. For the methods and usefulness of planned defecation through bowel habit instructions, please refer to "IV-A-2. Bowel Habit Instructions".

The use of appropriate absorbent products, such as pads and diapers, is essential for FI management. A survey of local residents regarding FI revealed that panty liners and sanitary pads, which can be changed frequently, were the most commonly used products, whereas pads and diapers designed for urinary incontinence were used by those with urinary incontinence in addition to watery stools and FI. The ratings for comfort and effectiveness against FI varied by product and individual, but odor control was rated low for all products[261]. The most cost-effective absorbent products for moderate to severe FI were disposable diapers for men and pads for women, indicating a gender difference. However, because of large individual differences, such as differences in preferences and lifestyles, it is not possible to

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determine the most useful type of product[262].

Because IAD occurs when stool comes into prolonged contact with the skin, prompt removal of stool attached to the skin is a basic principle to prevent IAD[263]. However, there are no studies with a high level of evidence on absorbent products for preventing IAD caused by FI[262]. The most effective method to prevent IAD is to keep moisture sources and irritants resulting from incontinence away from the skin to avoid skin maceration and contact with irritants[264,265].

A skin care method that is less irritating to the skin is the use of wet wipes containing a cleansing agent, moisturizer, and skin protectant (hereafter referred to as "triple-agent wet wipes")[266]. According to an RCT[267] comparing the incidence of IAD, the incidence was significantly lower with triple-agent wet wipes at 8.1% than with water and soap at 27.1%. These wet wipes are sold as "butt wipes" by various manufacturers in Japan. Alkaline soap is a chemical irritant to the skin. Thus, it should be avoided whenever possible [268]. A Cochrane review has shown that standardized skin care using triple-agent wet wipes may be more effective than skin care with water and soap for the prevention and treatment of IAD[268].

However, if wet wipes are not sufficient to remove stool attached to the skin, it is recommended to wash the skin using a skin cleaning agent or a mildly acidic (pH 5.5-7.0) skin cleanser and rinse off with lukewarm water[269]. When washing and rinsing, care should be taken to minimize mechanical irritation to the skin by lathering and gently washing the skin without using sponges or towels[123]. After cleansing, an emollient-based moisturizer, such as Vaseline, olive oil, and mineral oil, should be used[123]. The purpose is to replenish the intercellular lipids (hydrolipid film) of the skin and maintain normal barrier function by slowing down moisture loss from the skin. Furthermore, an RCT has shown that, in severe cases of IAD, the use of water-repellent skin protectants reduces erythema, increases the moisture content of the stratum corneum, and shifts the skin pH toward a slightly acidic level[269]. Moreover, a systematic review has shown that the use of IAD assessment tools, skin cleansers with a pH of 4.0-6.8, changing body position, and high-protein diet intake are effective prevention and care methods for IAD in older adults[270].

When perianal skin erosions are present as a form of IAD, in addition to standard skin care involving skin wiping, cleansing, and moisturizing, a powdered (CMC-based) skin protectant, which is a stoma care product, should be sprinkled on the affected area, followed by the application of a skin film agent[266]. If ulcers are present, consultation with a dermatologist or other healthcare professional should be considered to differentiate IAD from other diseases, such as Crohn's disease and herpes[271].

4. Drug therapy

Statement

$\bullet$ Calcium polycarbophil is recommended for treating cal incontinence associated with soft stools. Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ Loperamide hydrochloride is recommended for treating fecal incontinence associated with soft stools, but it is necessary to titrate its dosage depending on individual patients with attention to constipation as a side effect.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: A

$\bullet$ The administration of ramosetron hydrochloride is recommended to treat urge fecal incontinence in patients with diarrhea-predominant IBS.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ Rectal emptying with suppositories or enemas is recommended for treating fecal incontinence associated with defecation difficulty type constipation.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: C

$\bullet$ The use of daikenchuto is recommended to treat fecal incontinence associated with defecation difficulty type constipation.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

Currently, there is no prescription drug indicated for the treatment of fecal incontinence (FI) in Japan. However, many cases of FI are associated with defecation abnormalities, such as diarrhea and constipation. Thus, drugs that are indicated for these conditions can be used. In general, the looser the stool consistency and the more frequent the bowel movements, the greater the amount and frequency of incontinence. Therefore, in treating FI associated with soft or watery stools, antidiarrheals are used to solidify stool consistency and inhibit peristalsis of the large intestine. In contrast, suppositories and enemas are used to void the rectum in treating FI associated with defecation disorder and overflow FI. In treating FI associated with diarrhea caused by inappropriate or excessive use of laxatives, the type and dosage of laxatives should be adjusted appropriately.

Commentary

Major overseas guidelines recommend solidifying stool consistency using stool bulking agents, such as dietary fiber, and antidiarrheals as the initial treatment for FI[80,272]. Drugs that have been evaluated in RCTs for their efficacy in the treatment of FI include loperamide hydrochloride, psyl- lium (dietary fiber supplement), diphenoxylate (a natural opioid), codeine phosphate, tricyclic antidepressants, sucral- fate, and methylcellulose[69,273-275]. Of these, loperamide hydrochloride is the only drug that has been thoroughly in-

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vestigated and confirmed to be effective[176,274-278]. There are several other drugs effective in treating FI, although the level of evidence is not high. The appropriate drug should be selected based on the presence of defecation abnormalities (such as soft stools, watery stools, and incomplete defecation) associated with FI.

a. Calcium polycarbophil

Calcium polycarbophil (CP), used in Japan as a therapeutic drug for IBS, is a calcium salt of a high molecular weight absorbent polymer that becomes polycarbophil by releasing calcium ions under acidic conditions in the stomach, and it acts by absorbing intestinal liquid that is >35 times of its original weight under neutral conditions in the small and large intestines, swelling and gelling, and being almost 100% evacuated in the stool without being absorbed in the gastrointestinal tract. Because it softens hard stools and solidifies watery stools, it is used in both diarrhea-predominant and constipation-predominant IBS and is expected to be effective as a stool bulking agent in treating FI through the same mechanisms as dietary fiber[69]. CP is the most commonly prescribed drug for FI at major specialized facilities in Japan[279].

In contrast, CP is mainly sold as an over-the-counter drug overseas, and no RCT has been conducted on its use in patients with FI. In a 6-month RCT conducted overseas on patients with IBS, frequent bowel movements significantly improved in the CP 6 g/day group compared with that in the placebo group[280]. In Japan, Shibata et al.[281] conducted an RCT involving 21 patients after total colectomy and ileal pouch anal anastomosis and found that nocturnal soiling decreased in the CP group. In a case series by Abe et al.[282], 72 patients with FI of various stool consistency were treated with CP (0.5-1 g three times a day), and the median CCFIS improved significantly from 11 to 5. with side effects such as constipation, hard stools, and abdominal distention observed in 14% of the patients.

b. Loperamide hydrochloride

Loperamide hydrochloride is a potent antidiarrheal that acts on opioid receptors of the small and large intestines to inhibit peristalsis, inhibit the secretion of water and electrolytes in the intestinal tract, and facilitate absorption, thereby reducing the frequency of defecation and solidifying stool consistency. It is useful for the treatment of patients suffering from FI associated with loose stools, but excessive administration may cause constipation symptoms; thus, the dosage must be titrated depending on individual patients. As a guideline, bowel movements should be adjusted to range from every other day to twice a day, with stool consistency between types 3 and 4 of the Bristol Stool Form Scale[24,273,274]. If constipation symptoms occur even with 1-mg capsules, the dosage should be gradually increased starting with 0.5 mg/day using granules. The upper limit of the treatment dosage covered by insurance is 2 mg/

day, but if the effect is insufficient, a dosage increase should be considered (see CQ1)[24].

The effect of loperamide hydrochloride on FI with soft stools or diarrhea has been investigated in several RCTs, which showed a significant reduction in fecal urgency and frequency of FI as well as a higher rate of achieving full continence compared with those using placebo[69,272]. In an RCT comparing the efficacy of loperamide hydrochloride at 2-4 mg/day and psyllium in treating FI, the efficacy rate was about 60% in both groups, but the incidence of constipation symptoms was significantly higher with loperamide hydrochloride (29%) than with psyllium (10%)[274]. In contrast, loperamide hydrochloride has fewer central nervous system side effects than diphenoxylate and codeine phosphate, which are also μ-opioid receptor agonists, due to its low blood-brain barrier permeability[275]. Major overseas guidelines recommend loperamide hydrochloride as a first-line drug for FI associated with soft stools or diarrea[69,80,272]. Furthermore, a recent RCT has shown that loperamide hydrochloride is effective even in patients with normal stool consistencies and that the constipation symptoms do not worsen significantly[283]. Moreover, the oral administration of loperamide hydrochloride significantly increases resting anal pressure and voluntary anal contraction pressure, and its mechanism of action is believed to include direct action on the anal sphincters themselves, inhibition of acetylcholine release from nerve endings, and inhibition of prostaglandin synthesis[176,276,277].

c. Ramosetron hydrochloride

Ramosetron hydrochloride, a serotonin 5-HT₃ receptor antagonist, is used to treat urge FI in patients with diarrhead predominant IBS. This drug blocks 5-HT₃ receptors in the enteric ganglia of efferent nerves, thereby suppressing stress-induced colonic transport hyperactivity and alleviating diarrhea. In addition, it mitigates abdominal pain and visceral hypersensitivity by blocking 5-HT₃ receptors in afferent nerve endings. No RCT has been conducted on its use in patients with FI. In an RCT where 539 Japanese patients with diarrhea-predominant IBS were randomized to either the ramosetron (5 µg/day) group or the placebo group, the ramosetron group showed a significantly reduced frequency of bowel movements, firmer stools, and an improvement trend in fecal urgency over the 12-week treatment period[284]. In addition, in a multicenter RCT involving 576 female patients with diarrhea-predominant IBS, more patients in the ramosetron (2.5 µg/day) group had firmer stools and greater improvement in QoL than those in the placebo group. Side effects included constipation in 11% of patients in the ramosetron group[285]. In an RCT on male patients with LARS, the rate of severe LARS decreased from 88% to 58% in the ramosetron (5 µg/day) group after 4 weeks of treatment, but no change was observed in the conservative treatment group (pelvic floor muscle training, etc.) before

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and after treatment. Side effects such as hard stools and anal pain were observed in 10% of the patients in the ramosetron group[286].

d. Suppositories, enemas, etc.

In older adults, rectal hyposensitivity leads to decreased defecation behavior. Thus, overflow FI associated with rectal fecal impaction is more likely to occur. In addition to bowel habit instructions, periodic rectal emptying with suppositories or enemas may be effective in the treatment of FI associated with defecation difficulty type constipation [69,80]. Specific methods include planned defecation using weekly glycerin enemas in combination with regular administration of osmotic laxatives [287] and the use of enemas or bisacodyl suppositories as a rescue medicine when there has been no bowel movement for 3 days [288]. Chassagne et al. [289] conducted an RCT on 206 patients with FI residing in nursing homes for the older individuals, dividing them into the lactulose (30 g/day) alone group and the group receiving lactulose in combination with glycerin suppositories (daily) and once-weekly lukewarm water enemas, and found no difference in frequency of FI between the two groups. However, in cases where the rectum was emptied with suppositories and enemas, the amount of laundry for clothes and bedding decreased, reducing the workload of caregivers.

For rectal fecal impaction and encopresis in children, the administration of polyethylene glycol is recommended for both rectal fecal mass removal and the subsequent maintenance therapy[290]. Although its effect on FI in adults is unknown, polyethylene glycol has been reported to be effective in improving defecation difficulty and sensation of incomplete evacuation in older adults[291].

e. Daikenchuto

Daikenchuto is a traditional Chinese herbal medicine used for alleviating abdominal pain and abdominal distension, and its main herb, sansho, is believed to have a stimulating effect on vanilloid receptors expressed in mucosal epithelial cells and sensory nerve endings in the rectal and anal regions[292]. An RCT conducted at the Mayo Clinic on 45 patients with constipation suggested that the oral administration of daikenchuto (15 g/day) lowers the rectal sensory threshold[293]. In an observational study conducted in Japan on 15 children with severe constipation, the rectal sensory threshold was significantly decreased, and the constipation score was significantly improved after the administration of daikenchuto (0.3 g/kg/day)[294]. In addition, daikenchuto has also been suggested to increase the contractility of the internal anal spincter[293,295-297]. In an observational study of 157 patients (mean age of 74 years) with FI who had symptoms suggestive of defecation disorders, such as defecation difficulty and sensation of incomplete evacuation, daikenchuto (7.5 g/day) significantly improved the mean CCFIS from 10.4 to 8.4 with no side effects[296]. In a prospective study on daikenchuto (15 g/day) in patients older

than 70 years suffering from FI with abdominal pain and abdominal distension, FI disappeared in 11 out of 21 patients (52%), and the FIQL also improved significantly[297]. In addition, in both studies, resting anal canal pressure increased by approximately 20% after the administration of daikenchuto[296,297]. Thus, daikenchuto may be useful for older patients with FI who have rectal hyposensitivity and decreased resting anal pressure.

f. Other drugs (not covered by insurance for defecation abnormalities or abdominal symptoms)

Amitriptyline hydrochloride (20 mg/day), a tricyclic anti-depressant, administered to 18 patients with idiopathic FI for 4 weeks, significantly improved their median CCFIS from 16 to 3[298]. The mechanism of action of amitriptyline hydrochloride includes inhibition of rectal activity and improvement of anal sphincter contractility during rectal contraction through its anticholinergic, antimuscarinic, and serotonin-related actions.

Kusunoki et al. [299] demonstrated that the administration of sodium valproate, which is used to treat mania and epilepsy, to patients after ileoanal anastomosis improved defecation frequency, underwear soiling, and anorectal dermatitis, and increased resting anal pressure. Maeda et al. [300] reported that diazepam, an anxiolytic, is useful in the treatment of FI after low anterior resection. In addition, propivereine hydrochloride and darifenacin hydrobromide, which are used to treat frequent urination and urinary incontinence, and clonidine, which selectively stimulates α2 receptors in the brainstem, are effective in treating FI[301-303].

CQ1. How should calcium polycarbophil and loperamide hydrochloride be properly used in drug therapy for fecal incontinence?

Statement

$\bullet$ For fecal incontinence associated with soft stools, it is recommended to first solidify stool consistency with calcium polycarbophil, aiming for type 3 to 4 of the Bristol Stool Form Scale.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ For fecal incontinence associated with soft stools, if calcium polycarbophil at 3 g/day does not adequately solidify stool consistency and fecal incontinence does not improve adequately, it is recommended to combine loperamide hydrochloride to adjust stool consistency, aiming for types 3 to 4 of the Bristol Stool Form Scale.

Strength of Recommendation: Strong (Consensus Rate: 100%), Level of Evidence: A

Commentary

For fecal incontinence (FI) associated with soft stools and diarrhea, the use of stool bulking agents or antidiarrheals to solidify stool consistency is recommended as initial treat-ment[8,69]. Except in cases of severe diarrhea, it is common

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to start with stool bulking agents, which have fewer side effects[304,305]. Overseas guidelines list dietary fibers such as psyllium and methylcellulose as well as thickeners, such as gum arabic, as stool bulking agents[272]; however, in Japan, CP, a prescription drug, can be used as a stool bulking agent[306].

Patients with FI associated with loose stools of types 5 to 7 on the Bristol Stool Form Scale are to be first treated with CP at 0.5-1 g twice or twice a day for 2-4 weeks. If FI persists and the stool is still loose without reaching types 3 or 4, a sachet of loperamide hydrochloride granule should be added at 0.5 mg once daily (in the morning), with the dose titrated as needed, aiming for a defecation frequency of every other day up to twice a day and a stool consistency between types 3 and 4. When its daily dosage has reached 2 mg, loperamide hydrochloride can be prescribed as a 1 mg capsule that should be taken twice daily (in the morning and at night). Although 2 mg/day is the upper limit of the treatment dosage covered by insurance, the National Institute for Health and Care Excellence (NICE) guidelines recommend that the dosage can be increased up to 16 mg/day until the ideal stool consistency has been reached, as this drug is safe and effective in a dose-dependent manner [307]. However, caution is required as the US Food and Drug Administration issued a warning in June 2016 that the abuse of loperamide hydrochloride (average dosage in cases with side effects: 195 mg/day) could cause serious arrhythmias as an adverse effect [308].

B. Specialized conservative therapy

1. Pelvic floor muscle training

Statement

$\bullet$ PFMT with proper instructions is proposed for the treatment of fecal incontinence. Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Abstract

PFMT is a treatment that improves urinary and fecal incontinence (FI) by increasing the contractility of pelvic floor muscles, such as the levator ani and external anal sphincter, through contraction training.

Because the type of patients with FI benefiting from PFMT is not known, it is indicated for patients who can fully understand the instructions and are motivated to continue PFMT at home.

The efficacy rate of properly instructed PFMT in treating FI has been reported to be 41%-66%.

Commentary

PFMT, also called Kegel exercise, is a method advocated by the American obstetrician and gynecologist Kegel in the 1950s[309]. Typically, patients are instructed to contract their pelvic floor muscles for 10 seconds and then rest for 20 seconds while breathing normally with relaxed abdomi-

nal and buttock muscles. In a single set, this contraction is repeated 10-20 times, and patients are instructed to perform three to five sets of this exercise every day[7]. For patients who have difficulty maintaining sustained contractions, PFMT should be performed for as few seconds or as many times as possible. Although PFMT is generally instructed only verbally or in writing with a brochure, the effectiveness of the training is enhanced when therapists place their hand on the patients' abdomen and instruct the patients not to contract their abdominal muscles during the contraction exercise while checking the state of anal contraction by digital rectal examination or visual inspection and feeding back this information to the patients[310]. In patients with urge FI, it is particularly important to train the patients to relax their abdominal muscles and contract their pelvic floor muscles because the patients' whole body tends to tense up when holding back the urge to defecate, resulting in increased abdominal pressure that may induce FI. Although a report stated that FI was significantly improved in the group that received PFMT instructions from a physical therapist compared with that in the group that received only a brochure on PFMT[311], another report indicated that there was no significant difference between the two groups[312].

Most RCTS evaluating the efficacy of PFMT are studies in which PFMT was evaluated as a control against biofeed-back (BF) therapy[7,313,314]. The efficacy rate of PFMT for FI ranged from 41% to 66%, with another report stating that it is less effective than BF therapy[314] and others showing no significant difference between the two groups[312,315]. In an RCT verifying the effects of early postpartum PFMT instructed by a physical therapist, there was no difference in the frequency of anal incontinence between the group that received PFMT instructions and the group that did not; however, there was a significant increase in anal sphincter contractility and endurance in the group that received PFMT instructions[316]. Although PFMT may have a lower efficacy rate than BF therapy, PFMT alone improved FI in 41% of patients who had not shown improvement with other conservative therapies[314]. Therefore, PFMT is recommended with "Grade of Recommendation B" in the Incontinence 6th Edition[7] but is "weakly recommended" in the European guideline with a low level of evidence[69].

2. Biofeedback therapy

Statement

$\bullet$ Biofeedback therapy is proposed to be performed for the treatment of fecal incontinence.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: B Abstract

Biofeedback therapy is a type of pelvic floor physio- therapy that employs engineering devices to effectively im- part pelvic floor muscle training.

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Its purpose is to strengthen and sustain the contractility of the pelvic floor muscles, including the external anal sphinter, and to normalize rectal sensation through three methods, namely pelvic floor muscle contraction training, pelvic floor muscle coordination training, and normalization training of the rectal sensation.

Because it is not known what type of patients with fecal incontinence (FI) will benefit from biofeedback therapy, this therapy is indicated for patients with normal vision and hearing to recognize indicators from engineering devices and who can fully understand the instructions.

The efficacy rate of biofeedback therapy for FI has been reported to be 70%-80%, with an odds ratio of 1.2 (0.7-2.1) according to a meta-analysis of RCTs comparing it with other treatments.

Commentary

Biofeedback (BF) therapy is a treatment method that converts physiological phenomena in the body that are normally difficult to recognize into sensory signals that can be perceived using engineering devices, allowing the phenomena to be voluntarily controlled. PFMT and BF therapy for FI are collectively called pelvic floor physiotherapy, which is a type of physical therapy. The goals of BF therapy are to strengthen and sustain the contractility of the pelvic floor muscles, including the external anal sphincter, and to normalize rectal sensation[317]. Because the type of patients with FI benefiting from it is not known, BF therapy is indicated for patients who fully understand the instructions and are sufficiently motivated to continue pelvic floor muscle contraction training at home[9]. Although the efficacy of BF therapy for FI has not yet been confirmed, it is considered to be a treatment that may be performed when other conservative therapies are ineffective, as it has no side effects[8,305].

Methods: The following methods are used alone or in combination depending on individual pathological condition[305,318,319].

1) Pelvic floor muscle contraction training

This is a training to effectively strengthen the pelvic floor muscles, as patients themselves recognize the contraction state of their anal sphincter using anal manometry or electromyogram. The device used and the duration of treatment vary among institutions, and there is no standardized method. Generally, it is performed in an outpatient setting, and patients are instructed to perform three types of contraction methods, comprising the strongest contraction, prolonged contraction, and quick contraction, while the contraction state of the anal sphincters is fed back to the patients via waveforms on the display or signal sounds[318]. Although it is important to contract only the pelvic floor muscles, some patients tend to tense up their abdominal and thigh muscles. Therefore, it is more effective to attach surface electromyographs to the abdomen and thighs and pro-

vide feedback to patients on the state of activity of these muscles[319]. This outpatient instruction session is given once or twice a month, for a total of about five sessions. Patients are instructed to perform three to five sets of each of the three types of contraction training at home on a daily basis, each set consisting of 10 repetitions. Effects begin to appear several months after the start of treatment. The maximum voluntary contraction pressure and contraction duration (with the target being 10 s) are indicators to determine the effectiveness of the treatment.

2) Pelvic floor muscle coordination training

This is a training to improve the coordination between rectal sensation and contraction of pelvic floor muscles, including the anal sphincters. When stool accumulates in the rectum, the rectoanal inhibitory reflex is induced, causing the anal canal to relax and making FI more likely. This condition is reproduced with a rectal balloon, and the patients are trained to prevent FI by conscious contraction of their pelvic floor muscles. As the rectal balloon is inflated, the patients would feel the urge to defecate, and they are instructed to contract their pelvic floor muscles at the same time. The goal is to achieve the strongest contraction within one second after the balloon is inflated[320].

3) Normalization training of the rectal sensation

In general, rectal hyposensitivity tends to result in passive FI, whereas rectal hypersensitivity tends to result in urge FI[321]. In patients with rectal hyposensitivity (with the first sensation volume >100 mL) by rectal balloon sensation test, the balloon inflation volume is decreased by 10% from the first sensation volume in increments to train the patients to perceive smaller volumes[322]. This allows the patients to be aware of when to go to the toilet in time. In contrast, in patients diagnosed with rectal hypersensitivity (with the maximum tolerated volume <150 mL), the balloon inflation volume is gradually increased to train the patients to increase their tolerated volume. This allows the patients to hold their bowel movements until they go to the toilet. Sensation training was reported to be more effective than contraction training in improving FI symptoms[321].

Effectiveness: Many studies evaluating pelvic floor physiotherapy for FI have been reported, including approximately 30 RCTs[202,305,310,323]. In addition, nine systematic reviews and meta-analyses that comprehensively evaluated these studies have been reported[202,310,313,323-328].

The efficacy rate of BF therapy for FI is 70%-80%[310,324,329,330]. An RCT has reported that BF therapy (with an efficacy rate of 76%) was significantly more effective than PFMT (with an efficacy rate of 41%)[314]. In contrast, BF therapy was reported to be as effective as drug therapy and PFMT[312]. Therefore, the effectiveness of BF therapy has not been conclusively determined. This is attributed to the lack of uniformity in the frequency, duration, and methods of BF therapy as well as the differences in the

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instructing ability of therapists[305]. According to a meta-analysis involving six RCTs, the odds ratio for the efficacy of BF therapy compared with other treatments was 1.2 (0.7-2.1)[205], and a 2012 Cochrane review also concluded that the efficacy of BF therapy for FI is not definitive[313]. Therefore, pelvic floor physiotherapy was rated as “moderately recommended” with a low level of evidence in the 2022 European guideline[69]. In contrast, BF therapy, while requiring some specialized devices, effectively aids the instructions of PFMT without any side effects. Thus, it is “strongly recommended” with a moderate level of evidence in the 2021 ACG Clinical Guidelines[9] and recommended with “Grade of Recommendation A” in the Incontinence 6th Edition[305].

Regarding the effects of pelvic floor physiotherapy on different pathological conditions, effects before and after anal sphinteroplasty for FI caused by anal sphinter injury during childbirth, effects for perinatal FI, and effects for LARS have been evaluated in systematic reviews. It has been reported to have some effect, although not remarkable[310,327,328].

The effects of BF therapy are significantly enhanced when combined with medium-frequency anal electrical stimulation, and self-BF therapy at home is as effective as BF therapy at the hospital. These are subjects for future research[326,331-333].

3. Transanal irrigation

Statement

$\bullet$ Transanal irrigation is recommended only for patients with severe fecal incontinence when it is worth the time and effort required for irrigation.

Strength of Recommendation: Strong (Consensus Rate: 90.9%), Level of Evidence: B

Abstract

Transanal irrigation, or retrograde colonic irrigation, is a treatment in which the rectum and left colon are periodically emptied by transanal irrigation. This treatment is indicated for patients with severe constipation or fecal incontinence (FI). It is indicated in patients with spinal cord injury and in children with spina bifida, who often have both symptoms of constipation and FI. Overseas, it is also applied for patients with defecation disorders following low anterior resection. In Japan, it is covered by insurance for patients with defecation disorders caused by spinal cord injury that do not improve adequately with conservative treatment for more than 3 months (excluding patients who have had rectal surgery).

Commentary

Transanal irrigation (TAI) is a bowel management technique in which 300-1,000 mL of warm water is infused transanally into the rectum via a balloon catheter daily or every other day to evacuate stool from the rectum to the descending colon[334]. In TAI, the infusion of irrigation fluid

requires approximately 15 minutes, and the complete evacuation of the infused warm water takes approximately 45 minutes. It can only be continued if the patient has severe constipation or FI for which the effort and time are worth it. However, if treatment can be continued without undue psychological and physical burden, severe FI can be alleviated, and QoL can be improved[335-337].

The level of evidence regarding the utility of TAI for in-tractable defecation disorders is relatively high, as there are two RCTs[335,338], eight reviews, and numerous observa- tional studies on it. In an RCT comparing TAI with other conservative treatments in 87 patients with neurogenic bowel dysfunction, the CCFIS, St. Mark's Score, and neurogenic bowel disorder (NBD) Score significantly improved in the TAI group[335]. Additionally, a cost-effectiveness analysis using data from the same RCT showed that TAI was more cost-effective than other conservative treatments[339]. In an observational study of 348 patients with bowel defecation disorders associated with various etiologies, 145 patients (42%) continued to use TAI during a mean follow-up period of 21 months. The treatment success rates were higher in patients with neurogenic bowel dysfunction (63%) and anorectal dysfunction (51%) and lower in patients with post- operative anorectal dysfunctions (29%) and idiopathic con- stipation (34%)[340]. In addition, out of a total of 110,000 irrigation procedures, two cases of bowel perforation (one in the rectum and one in the sigmoid colon) occurred. Despite its low incidence, caution should be exercised.

In Japan, the Peristeen® anal irrigation system (Coloplast Japan, Tokyo) was approved in 2016 as a dedicated device for TAI. In 2017, a prospective multicenter study was conducted using this system in patients with intractable defecation disorders[334]. Among the 32 patients (median age 55.5 years, 19 men) who initiated TAI, 25 (78%) completed the 10-week TAI, and 23 (72%) wished to continue TAI after the study had ended. Patient satisfaction with bowel movements was also significantly improved. However, colonic perforation was noted in three patients (9.4%). While one patient was healed conservatively, the other two required stoma creation. Based on these domestic findings, TAI has been covered by insurance since 2018 under the category of "Home Transanal Self-Irrigation Guidance and Management Fee". However, all three patients in whom colonic perforation occurred had a history of surgery for either rectal cancer or rectal prolapse. Thus, patients with a history of rectal surgery were not eligible for insurance coverage. From 2020, it has become possible to calculate the "surcharge for materials for home transanal self-irrigation". However, as of April 2023, TAI is still covered by insurance only for "patients with bowel defecation disorders caused by spinal cord injury who do not improve adequately with conservative treatment for more than 3 months (excluding patients who underwent rectal surgery)."

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In contrast, TAI is also performed overseas for LARS. In an observational study involving 26 patients with LARS, 21 patients (81%) continued the use of TAI, of whom 15 (71%) had complete resolution of FI[341]. In addition, in a prospective observational study of 14 patients with LARS, the median frequency of defecation significantly decreased both during the daytime (from eight times to once a day) and the nighttime (from three times to none in a day), the CCFIS significantly improved from 17 to 5, and QoL also significantly improved during a median follow-up period of 29 months[342]. Recently, a cone catheter with a conical tip was developed to enhance the safety of TAI for patients with defecation disorders after rectal surgery, including those with LARS, and was approved in Japan in 2020. The cone catheter does not have a balloon attached. Thus, it is necessary to hold the catheter in place during the infusion of irrigation fluid. However, it can prevent bowel injury associated with balloon inflation, and the catheter tip is designed to extend the upper border of the anal canal slightly. Thus, there is a lower risk of bowel injury caused by the catheter tip[343]. A multicenter RCT has been conducted to compare the efficacy and safety of TAI using a cone catheter against standard treatment for LARS. The results showed that the LARS score (21.3 for TAI vs. 32.2 for standard treatment), major LARS rate (33% vs. 67%), and patient satisfaction scores (8.6 vs. 6.7) after 3 months were significantly better in the TAI group (15 patients) than in the standard treatment group (15 patients)[338]. In addition, no serious adverse events, such as bowel perforation, occurred in the TAI group using a cone catheter. We hope that TAI using a cone catheter will soon be covered by insurance in Japan for patients with intractable defecation disorders after anorectal surgery, including LARS.

TAI is a vital treatment method for intractable defecation disorders caused by spinal cord injury and is located in the middle tier of the treatment concept (see Figure 8 in VI-A.) with colostomy at the top, that is, on the border between conservative therapies and surgical treatment[344]. Therefore, TAI serves as a valuable presurgical treatment option for patients with severe bowel defecation disorders for whom conventional conservative therapies are ineffective or problematic.

When implementing TAI, it is recommended to refer to the "Guidelines on the Indications and Instruction Management of Transanal Irrigation"[345] and the "Guidelines on the Indications and Instruction Management of TAI for Intractable Defecation Disorders caused by Spinal Cord Injury"[346] published on the websites of the Japan Society of Coloproctology and the Japan Medical Society of Spinal Cord Lesion, respectively.

Regarding the statement at the beginning, "Transanal irrigation is recommended for patients with severe FI that is worth the time and effort required for irrigation," there were

![graph TD\n A1[Soma] --> A2[Sacral neuromodulation]\n A2 --> A3[Antegrade continence enema]\n A3 --> A4[Transanal irrigation]\n A4 --> A5[Digital evacuation Stool suppositories Enema]\n A5 --> A6[Nutrition Fluid intake Lifestyle changes Drugs]\n A6 --> A7[Conservative therapies]\n A7 --> A4\n A7 --> A8[Surgical treatment]\n A8 --> A1\n](1/parseimages/figurebdb5bddb1900461191e80322469ab29b_0_6.png) opinions in favor of recommending it as a weak recommendation in the vote to determine the strength of recommendation among the Guideline Drafting Committee.

4. Other conservative therapies

a. Tibial nerve stimulation

Statement

$\bullet$ The evidence for the efficacy of tibial nerve stimulation (TNS) is low, and currently, it cannot be considered effective for fecal incontinence. Because it has not been approved in Japan, it is limited to use within the framework of clinical research.

Abstract

TNS is a treatment to improve fecal incontinence (FI) using an external nerve stimulator to electrically stimulate the tibial nerve, which runs behind the ankle medial malleolus. There are two methods: percutaneous TNS (PTNS), which involves the insertion of a needle electrode through the skin, and transcutaneous TNS (TTNS), which uses the adhesive of an electrode pad on the skin. Compared with sacral neuro-modulation, TNS is less invasive, more cost-effective, and associated with fewer adverse events; however, TNS should only be performed within the framework of clinical research. Because the evidence for its efficacy is low, no dedicated medical device is available in Japan, and it is not covered by insurance.

Commentary

TNS can improve FI by electrically stimulating the sacral nerve plexus, similar to sacral neuromodulation, as the tibial nerve originates from the sacral nerve[347]. TNS is less invasive, cost-effective, and associated with fewer adverse events than sacral neuromodulation. However, its effectiveness in improving FI has not yet been conclusively determined. This is because the therapy's optimal stimulation

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conditions and methods are unknown and have not been standardized.

A systematic review [347] of TNS identified six studies on PTNS, five studies on TTNS, and one study that examined both methods. Of these studies, 10 were case studies, and the remaining 2 were RCTs. According to the systematic review, the success rate of PTNS (the percentage of cases with ≥50% reduction in FI episodes per week) ranged from 63% to 82%, whereas that of TTNS ranged from 0% to 45%. In conclusion, both PTNS and TTNS showed some improvement in FI; however, in an RCT comparing TTNS with sham stimulation in 144 patients, the usefulness of TTNS was not proven, indicating that it could be merely a placebo effect [348]. No conclusion could be drawn regarding the efficacy of PTNS, as there was no RCT comparing PTNS with sham stimulation. Subsequently, an RCT comparing PTNS with sham stimulation in 227 patients was reported, showing no significant difference in success rate between the two groups; thus, the usefulness of PTNS was not proven [349]. A more recent systematic review and meta-analysis integrated five RCTs and compared 249 patients who underwent PTNS with 239 patients who underwent sham stimulation. Although the study revealed a significant decrease in the frequency of FI in the PTNS group [350], there were no significant differences in FI score, resting anal canal pressure, voluntary contraction pressure, and maximum tolerated volume between the two groups, indicating that PTNS alone was deemed Insufficient to improve FI [350].

In Japan, a prospective observational study of bilateral transcutaneous posterior TNS (BTPTNS), which stimulates bilateral tibial nerves, showed that the frequency of FI episodes was reduced by ≥50% in 17 out of 22 patients (77.2%)[351]. Because the innervation of pelvic organs is not always symmetrical, BTPTNS may activate more afferent sensory pathways, potentially enhancing therapeutic effects[352].

b. Anal electrical stimulation

Statement

$\bullet$ Anal electrical stimulation (AES) is not considered helpful for fecal incontinence when used alone; however, it may be beneficial when combined with anal electromyographic biofeedback therapy. Nevertheless, it is limited to use within the framework of clinical research, as it has not been approved in Japan.

Abstract

AES is a treatment that improves fecal incontinence (FI) by electrically stimulating the anal canal with a stimulation electrode inserted in it. The target patients benefiting from this therapy are unknown, and the evidence supporting its efficacy is low. This therapy should only be performed within the framework of clinical research, as there is no dedicated stimulation electrode or stimulator commercially

available in Japan, and it is not covered by insurance.

That said, an RCT reported that the FI score was significantly improved when amplitude-modulated medium-frequency anal electrical stimulation was combined with anal electromyographic biofeedback therapy compared with either AES alone or biofeedback therapy alone. Thus, this finding highlights a promising area for future research.

Commentary

The mechanism by which AES improves FI is believed to involve stimulating the neuromuscular junction of the anal sphincter muscles, which passively contracts the anal sphincters, thereby enhancing their contraction strength[353,354]. Generally, in voluntary contraction exercises, such as pelvic floor muscle training or biofeedback (BF) therapy, thin slow-twitch muscle fibers (type I fibers) are activated, and thick fast-twitch muscle fibers (type II fibers) are gradually recruited as the exercise load increases[354]. Therefore, an exercise intensity of ≥50% maximal muscle strength is required to activate fast-twitch muscles. In contrast, therapeutic electrical stimulation preferentially activates fast-twitch fibers because of their larger motor nerve axon diameters and lower electrical resistance; thus, it can effectively strengthen fast-twitch fibers crucial for maximum muscle strength[326,354]. Therefore, by combining voluntary contraction training and passive contraction using electrical stimulation, slow- and fast-twitch fibers can be strengthened in a well-balanced manner. As a result, AES for FI is often performed along with BF therapy and other pelvic floor physiotherapy methods[326,353].

In an RCT involving 40 patients with FI caused by obstetric trauma, the combination group receiving AES and anal electromyographic BF (EMG-BF) had significantly more patients who had been healed or improved than those in the BF alone group using a vaginal manometer[355]. Mahony et al.[356] conducted an RCT on 60 patients with early postpartum FI, compared the combination group receiving AES once a week for 12 weeks and EMG-BF with the group receiving EMG-BF alone, and reported that FI scores and voluntary anal contraction pressure improved in both groups but resting anal canal pressure showed no significant improvement, suggesting that AES had little additional effect. In another RCT comparing AES (frequency 35 Hz) and sham stimulation (1 Hz) for 8 weeks, FI symptoms improved in both groups. The fact that the effect was obtained even with 1 Hz, which does not induce muscle contraction, suggested that the contraction of the anal sphincters is not necessarily required for the effect to be manifested and that physical stimulation of the anal region and improved sensation may be involved[357]. While the efficacy of AES alone has been reported in several case series[358-360], different stimulation electrodes and devices, as well as current intensity, frequency, pulse width, and energization time have not been standardized. Consequently,

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the 2007 Cochrane review concluded that although AES may be effective for FI, the available data were insufficient to draw reliable conclusions regarding its effectiveness[353].

AES typically uses low-frequency ranges (20-100 Hz), which are more likely to induce muscle contractions. However, low-frequency stimulation stimulates nociceptors in the skin and mucous membranes, causing pain when the current is increased[326,354]. To address this issue, a method has been attempted to stimulate the anal sphincters and pelvic floor more effectively using medium frequency (1,000-10,000 Hz), which is associated with a lower skin resistance, to apply a much higher current than low frequency while moderating the stimulation[326]. In an RCT comparing the “triple target (3T)” group using a combination of amplitude-modulated medium-frequency (AM-MF) AES and EMG-BF with the EMG-BF alone group, the median CCFIS improvement range was three points higher in the 3T group than in the EMG-BF alone group, demonstrating the superiority of 3T therapy[331]. Furthermore, in another RCT comparing the effects of low-frequency AES and 3T therapy on FI, the median CCFIS improvement range was seven points higher in the 3T group (p < 0.001)[332]. Based on these results, a 2013 systematic review concluded that the combination of AM-MF AES and EMG-BFIs is the most optimal approach for the professional conservative treatment of FI[326].

The anticipated effects of AES include sphincter strengthening in patients who cannot voluntarily contract their anus and functional recovery of the internal anal sphincter, which is challenging to strengthen through voluntary exercises[326]. Although AES primarily activates type II fibers, medium-frequency stimulation with a large electric current can strengthen the internal anal sphincter, which consists of type I fibers. This remains an important subject for future research.

c. Anal insert device

Statement

$\bullet$ Anal insert devices can be an effective treatment for fecal incontinence in patients who can use them continuously without experiencing any discomfort. However, they are not currently available for sale in Japan.

Abstract

Anal insert device is a treatment modality to prevent fecal incontinence (FI), in which a dedicated device is plugged into the anus and retained in the rectum to block the anal canal. Patients with normal rectal sensitivity or rectal hypersensitivity often cannot tolerate the discomfort caused by the retention of the device in the anorectum; thus, this treatment is considered suitable for older individuals with diminished rectal sensation or patients with spinal cord injuries, as they are less likely to experience discomfort from the device. This treatment can also effectively prevent FI in patients with normal rectal sensitivity if they can continue using the

anal insert device without experiencing any discomfort. Therefore, this treatment may be a valuable option for patients who have not responded to or are unsuitable for other conservative treatments. Currently, however, anal insert devices are not commercially available in Japan.

Commentary

Several shapes and materials of anal insertable devices have been developed and used[361,362]. The Peristeen® Anal Plug (hereafter referred to as Anal Plug®) was previously sold in Japan[363]; however, because of changes in European medical device regulations, its production was discontinued in June 2023. As a result, anal insertable devices are currently not commercially available in Japan.

According to the latest systematic review on insertable devices for the treatment of FI, 11 studies that examined anal incontinence devices from 1991 to 2019 included six focused on the Coloplast ‘Tulip’ design (Anal Plug®), 2 on the Procon/ProTect device, and 3 on the Renew® Insert[363]. While all devices were associated with issues, such as discomfort during use and displacement, they improve FI and QoL if the patients could tolerate their use[364]. Although no serious complications have been observed with the Anal Plug®, discomfort associated with its retention, fecal urgency, pain, and bleeding from hemorrhoids prevent its continuous use in 12.5%-70% of patients[362,364-366]. In a prospective study evaluating the efficacy of Anal Plug®, 7 (23%) out of 30 patients with FI discontinued its use within 1 week because of discomfort. However, 23 (77%) continued its use for 3 weeks, among whom 21 (70%) requested further continued use[366]. In the group of 21 patients who wished to continue using the device, the degree of FI control was 9 points (0: worst to 10: best), the median usage time per Anal Plug® was 8 hours, and the median number of Anal Plug® used per day was two pieces[366].

The Renew® Insert (hereinafter referred to as Renew®; Renew Medical, UK) is a relatively new anal insert device that is soft, as it is made of silicone, and was designed to be comfortable for implantation. In a multicenter observational study involving 91 patients with FI with a CCFIS of ≥12, 73 patients (80%) could continue using the device for 12 weeks, and FI was reduced by half in 56 (77%) of these patients[367]. The volume of the rectum occupied by Renew® (Regular: 0.5 mL, Large: 0.8 mL) is significantly smaller than that of Anal Plug® (S: 8 mL, L: 13 mL), and its introduction in Japan would expand the options of therapies for FI.

The Navia Insert (Wellspect, UK) is another anal insert device sold overseas as a medical device. Although no clinical studies have been conducted on this device, it is anticipated that this device could be introduced in Japan as an alternative to the Anal Plug®.

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Abstract

Vaginal insert device is a fecal incontinence (FI) treatment device for women for the prevention of FI. A dedicated device is inserted and placed in the vagina, and a balloon is inflated in the vagina to extramurally block the rectum just above the anal canal. The Eclipse System is one of the dedicated devices. However, in Japan, it is not commercially available, is neither approved nor covered by insurance, and thus is limited to use within the framework of clinical research.

This device cannot be placed properly in 20%-30% of patients, but its treatment success rate after 1 year is approximately 70% in patients in whom the device can be placed properly without discomfort. Its main adverse events are vaginal mucosal injury and bleeding, urinary incontinence and urgency, and vaginal and pelvic discomfort, most of which are noticed during the trial insert period, and no serious adverse events have been reported.

Commentary

Vaginal insert device is a FI treatment device for women. In the treatment, a dedicated device is inserted and placed in the vagina, and a balloon is inflated in the vagina to extra-murally block the rectum just above the anal canal for the prevention of FI. The Eclipse System (Pelvalon, USA) is one of the dedicated devices, but it has not been approved in Japan. The insertion part of the Eclipse System is called an insert, and a balloon is attached to the rectal side of the silicone-coated stainless-steel base. The balloon is inflated by a removable pressure-regulating pump to block the rec-tum anteriorly and extramurally. When patients want to defecate, they deflate the balloon by manipulating the pump on their own. This device can be used in patients who have undergone hysterectomy[368] and is contraindicated in the presence of vaginal infection or an open wound.

The same research group has reported three prospective multicenter cohort studies on the usefulness of this therapy[368-370]. In the first study by Richter et al.[368], who have developed this system, 110 adult women with four or more episodes of FI in 2 weeks were fitted with the system, and the usefulness of this therapy could be evaluated in only 61 women (56%) because 49 women dropped out, including 32 (29%) in whom the system could not be properly placed in the vagina. Of the 61 women, 48 (78%) achieved treatment success with a reduction of ≥50% in FI frequency after 1 month of use, and 38 (62%) achieved treatment success after 3 months of use. The main adverse events in the 110 women fitted with this system were pelvic spasm/discomfort in 25 women (23%) and urinary incontinence/urgency in 13 women (12%), most of which were noticed during the trial insert period, and no serious adverse events have been reported. Varma et al.[369] conducted a secondary analysis on defecation symptoms other than FI in 56 patients in the study by Richter et al.[368]. This therapy significantly re-

duced the percentage of patients experiencing urgency during defecation from 73% to 39% and the percentage of patients with the sensation of incomplete evacuation from 55% to 36% compared with those before treatment. Based on this, How et al. [364] concluded in a systematic review that this therapy could be particularly useful in treating fecal urygency and urge FI. In addition, Richter et al. [370] conducted a study to evaluate the durability of the effect over a 12-month period in the patients who had achieved treatment success with a reduction of ≥50% in FI frequency in a 2-week trial insert period, and 137 adult women with four or more episodes of FI in the 2 weeks were fitted with the system, and 52 women dropped out, including 28 (20%) in whom the system could not be properly placed. Thus, only 85 women (62%) completed the 2-week trial insert period. The success rate, based on 73 women (86%: 73/85) who achieved treatment success during the 2-week trial insert period, was 73% after 3 months, 71% after 6 months, and 70% after 12 months. Compared with before treatment, FI frequency significantly improved from a mean of 7.1 episodes per week to 0.9 episodes per week and the St. Mark's Score significantly improved from a mean of 16.5 points to 9.8 points after 12 months, and 43 (80%: 43/54) of the 54 women (74%: 54/73) who had continued this therapy up to 12 months were aware of significant improvement in their FI symptoms, and 51 women (94%: 51/54) were satisfied with the therapy. Of the 137 women who were fitted with this system, adverse events were observed in 62 women (45%), with the main adverse events being vaginal mucosal injury and bleeding in 40 women (29%); lower urinary tract symptoms, such as urinary incontinence and urgency, in 20 women (15%); and vaginal and pelvic discomfort in 18 women (13%), most of which were noticed during the trial insert period, and no serious adverse events have been reported.

The evidence for the usefulness of this therapy is limited, as it has only been evaluated by the same research group. In Japan, no dedicated device is commercially available, and this treatment is neither approved nor covered by insurance. Thus, it can only be performed within the framework of clinical research. However, because it is a minimally invasive and simple treatment, we hope that it will be introduced in Japan.

V. Surgical Treatment for Fecal Incontinence

Standard surgical treatments for fecal incontinence (FI) include anal sphincteroplasty and sacral neuromodulation as the first-line surgical treatments and stoma construction as the second-line surgical treatment. In addition, special surgical treatments, such as antegrade continence enema (ACE), graciloplasty, and VR, are included in the flowchart but are only performed in a limited number of institutions. Other

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surgical treatments include biomaterial injection, which is currently not available in Japan but is performed overseas, and anal sphincter regenerative therapy, whose development is anticipated in the future. In contrast, artificial bowel sphincter, magnetic anal sphincter, and puborectal sling, which had been included in the first edition of these guidelines, are not included in this revised edition because they are no longer performed even overseas because of concerns about complications resulting from the implantation of artificial materials.

The level of evidence for surgical treatment in treating FI is generally low, except for novel procedures, such as sacral neuromodulation, which has been covered by insurance in Japan since 2014. This is mainly because RCTs and large-scale clinical trials are difficult to conduct owing to the nature of the surgical treatments. Other factors contributing to the low level of evidence were the lack of standardized definitions for FI and fecal continence as well as the lack of standardized methods for evaluating the severity of FI in the past. However, currently, evaluation methods are becoming standardized, as many studies use “a reduction of ≥50% in FI frequency” as the definition of successful treatment and the FIQL as the FI-specific QoL evaluation scale, thereby improving the level of evidence for surgical treatment.

Although the surgical treatment flowchart for FI has been modified over time, surgical treatment should be selected in order, starting with the most minimally invasive procedure, as FI is a benign condition. For these surgical treatments to be properly selected and performed in Japan, the characteristics of each treatment must be well known. This section provides an abstract and commentary covering each treatment.

In addition, for FI caused by organic diseases or anatomical abnormalities, such as rectal prolapse, prolapsed internal hemorrhoids, and rectavoginal fistula, treating the underlying disease often improves FI. Thus, this section does not cover treatment for these conditions.

A. Standard surgical treatment

1. Anal sphincter repair/sphincteroplasty Statement

* Anal sphincter repair/sphincteroplasty is proposed to be performed for the treatment of fecal incontinence caused by laceration of the anal sphincter resulting from childbirth trauma. The short-term outcomes are favorable, but the outcomes deteriorate in the long term.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: B

Abstract

The surgical techniques of anal sphincter repair/sphincteroplasty for third- and fourth-degree perineal lacerations include direct repair and overlapping sphincteroplasty, which have similar efficacy in the short term. Complications in-

clude wound infection, wound dehiscence, and rectovaginal fistula. In the long term, the treatment effects often deteriorate, and in such cases, other treatments, such as drug therapy, biofeedback training, and sacral neuromodulation, are recommended rather than repeating anal sphincteroplasty.

Commentary

Anal sphincter repair/sphincteroplasty is a procedure that usually involves suturing lacerated anal sphincter tissue caused by vaginal trauma. Repair performed immediately after trauma is called anal sphincter repair, whereas repair performed later is called anal sphincteroplasty. There are two surgical techniques, namely direct repair, which involves directly suturing anal sphincter edges, and overlapping sphincteroplasty, which involves suturing the superimposed anal sphincter and scar tissue together [371]. Randomized clinical trials comparing these two techniques have reported similar efficacy [372].

This surgical procedure is mainly indicated for third- and fourth-degree perineal lacerations resulting from childbirth. Occasionally, this procedure is performed after anal fistula surgery or after traffic accidents, but there is a lack of evidence on its efficacy in these cases. The short-term efficacy for childbirth-induced trauma has been reported to be 60%-85%[373,374]. One study in Japan reported significant improvement in CCFIS and maximum squeeze pressure at 3 months after surgery compared with before surgery[375]. Complications include wound infection, which can lead to wound dehiscence and may also lead to rectovaginal fistulas[376]. Prognostic predictors of failure of anal sphincteroplasty include pudendal neuropathy, history of anal sphincteroplasty, advanced age, and impaired rectal sensation[377]. In high-risk patients, the possibility that the surgical outcome may not be as expected should be fully explained, and informed consent should be obtained.

Although anal sphincteroplasty for childbirth trauma has favorable short-term outcomes, as described above, the efficacy of treatment has been reported to decline to 10%-14% in the long term[374,378-381]. Reasons for this include atrophy of the anal sphincter tissue caused by degeneration of the anal sphincter due to aging, tissue extension, and decreased pudendal nerve function. One study showed that repeat anal sphincteroplasty is effective in 50% of patients[382]; however, because of the small number of cases and a lack of other reports, repeat anal sphincteroplasty is generally not recommended. In addition, in patients in whom several decades have passed since the trauma, it is difficult to obtain desired outcomes from anal sphincteroplasty because of aging. Therefore, initial drug therapy and other conservative treatments, such as biofeedback training, should be offered first. If no improvement is observed, sacral neuromodulation is recommended[383].

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CQ2. When is the best time to refer patients with fecal incontinence after delivery to a specialized facility?

Statement

$\bullet$ If fecal incontinence, rectovaginal or recto-perineal fis-tula, or delayed perineal wound healing caused by anal sphincter injury is suspected after vaginal delivery, re-ferral to a specialized facility where surgical treatment is available is proposed. $\bullet$ Fecal incontinence in the absence of clinical evidence of anal sphincter injury, rectovaginal or recto-perineal fistula, or delayed perineal wound healing should be treated with initial treatment in obstetrics or gastroen-terology outpatient clinics during the first year after delivery, and if fecal incontinence persists 1 year after delivery, referral to a specialized facility is proposed. Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Commentary

There is a paucity of literature describing the timing of consultation and referral to specialist facilities for postpartum fecal incontinence (FI). This issue has been addressed in reports from clinics specializing in postpartum pelvic floor disorders [209,384] and the Royal College of Obstetricians and Gynaecologists guidelines for the management of third- and fourth-degree perineal lacerations (anal sphincter injuries)[208] (Table 7).

OASIS is an important risk factor for FI after vaginal delivery, and if they are not diagnosed and treated as needed, FI can lead to a lifelong decline in QOL[384]. In particular, if a severe perineal wound dehiscence or a large amount of fecal discharge from the vagina is observed immediately after anal sphincter repair for OASIS, the repair may be inadequate, and early re-repair is desirable. Thus, we propose an immediate referral to a specialized facility where surgical treatment is available.

In addition, even if the condition is not severe enough that no severe perineal wound dehiscence or fecal discharge in a large amount from the vagina is observed, if FI, recovaginal or recto-perineal fistula, or delayed perineal wound healing caused by OASIS is suspected, we propose an immediate referral to a specialized facility where surgical treatment can be performed, within reasonable limits. According to a report by Wan et al.[209] on the performance of a perineal clinic (a clinic specializing in postpartum pelvic floor disorders), of 3,254 first-time patients, 1,892 (58.1%) had OASIS and 765 (23.5%) had perineal wound complications. In addition, they reported that patients with OASIS of grade 3b or higher, with injury extending to more than 50% of the thickness of the external anal sphincter, had a higher incidence of FI, lower anal pressure, persistent anal sphincter defects on endoanal ultrasonography, a higher incidence of fistula formation, and a higher need for anal sphincter resuturing. Furthermore, Johannessen et al.[210] reported that

OASIS extending to the internal anal sphincter (3c) or to the anal epithelium (grade 4) was associated with a higher risk of developing FI than OASIS extending to the external anal sphincter (3b or lower). Sultan and Thakar[385] reported that patients with grade 3 or 4 OASIS at a high risk of developing FI should pay attention to signs of wound infection and deiscence, such as increased pain, anal bleeding, and purulent discharge from the wound, during the first 6-8 weeks postpartum. Moreover, Jibrel et al.[384] reported from a facility specializing in postpartum patients that the average timing of first visit in 1,138 patients was 64 days (26-160 days) postpartum, and surgery was performed in 103 patients (9.1%) within 1 year after the first visit. Of the patients indicated for surgery, 53 (51.5%) underwent it for FI, and in terms of surgical procedure, 39 (37.9%) underwent anal sphincteroplasty for OASIS, 34 (33.0%) underwent perineal laceration re-suturing, and 20 (19.4%) underwent rectovaginal fistula repair, with an average of 153 days (79-282 days) from delivery to surgery. In conclusion, wound management in obstetrics should be prioritized within the first 2 months after vaginal delivery because of the high incidence of complications associated with the wound healing process. However, at the same time, considering the need for subsequent surgical treatment for OASIS, if FI, rectovaginal or recto-perineal fistula, or delayed perineal wound healing caused by OASIS is suspected, we propose an immediate referral to a specialized facility where surgical treatment can be performed, within reasonable limits.

Johannessen et al. prospectively studied the course of anal incontinence, including gas incontinence, after delivery in 1,571 primiparas at the end of pregnancy as well as at 6 months, 1 year, and 6 years postpartum and noted that 65% of the women had natural vaginal delivery, 20% had abnormal vaginal delivery, such as vacuum forceps delivery and delivery complicated by OASIS, and 15% underwent cesearan section. The prevalence of anal incontinence after delivery was highest in patients who had undergone instrumental delivery, followed by normal vaginal delivery and cesarean section. However, the incidence of anal incontinence immediately after delivery was approximately 20% regardless of the mode of delivery. In addition, regardless of the mode of delivery, anal incontinence improved and the prevalence decreased up to 1 year postpartum. However, the prevalence of anal incontinence at 6 years was highest in patients who had undergone instrumental delivery (23%) compared with those who had undergone normal vaginal delivery (12%) or cesearan section (8%). The guideline published by the Royal College of Obstetricians and Gynaecologists [208] recommends that patients who have undergone anal sphincter repair for OASIS be informed that 60%-80% of patients are asymptomatic with respect to anal incontinence after 1 year. In conclusion, FI in the absence of clinical evidence of OASIS,

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rectovaginal or recto-perineal fistula, or delayed perineal wound healing can be expected to improve spontaneously with the recovery of pudendal neuropathy. Thus, it is advisable to treat it with initial treatment, such as drug therapy, in obstetrics or colorectal outpatient clinics during the first year after delivery.

In contrast, if FI persists 1 year after delivery, it may be due to clinically undiagnosed OASIS or may require treatment regardless of the cause. According to a meta-analysis of studies evaluating the relationship between anal incontinence and the diagnosis of OASIS by ultrasonography (103 studies, 16,110 patients)[211], among women after vaginal delivery, 26% were diagnosed with OASIS by ultrasonography and the prevalence of anal incontinence was 19%. In addition, in 3,688 women with clinically unsuspected OASIS, 13% were diagnosed with OASIS by ultrasonography, and the prevalence of anal incontinence was 14%. Furthermore, of 7,549 patients who underwent anal sphincter repair for OASIS, 55% had residual anal sphincter defects on ultrasonography, and the prevalence of anal incontinence was 38%. The prevalence of anal incontinence was significantly (3.74 times) higher in patients diagnosed with OASIS than in those in whom OASIS was not observed on ultrasonography. Thus, this meta-analysis demonstrated the importance of diagnosing the presence or absence of OASIS by ultrasonography, even if OASIS is not clinically detected. Moreover, Wan et al.[209] performed endoanal ultrasonography on 134 patients with anal incontinence despite no clinical diagnosis of OASIS and found OASIS in 40 patients (30%). Of the 134 patients, 25 (19%) received biofeedback therapy, 6 (4.5%) anal sphincteroplasty, and 1 (0.7%) sacral neuro-modulation. In conclusion, if FI persists 1 year after delivery, it may be due to clinically undiagnosed OASIS. Thus, we propose referral to a specialized facility where endoanal ultrasonography is available. At specialized facilities, FI can be expected to improve with specialized treatments, such as biofeedback therapy, anal sphincteroplasty, and sacral neuro-modulation, depending on the cause and severity of the FI.

CQ3. Which mode of delivery is recommended for pregnant women with a history of obstetric anal sphincter injury: vaginal delivery or cesarean section?

Statement

* If a patient has a history of anal obstetric anal sphincter injury, it is recommended that pregnant women have a consultation with a specialist regarding the next mode of delivery if they want.

Strength of Recommendation: Strong, (Consensus Rate: 100%), Level of Evidence: C

* If a pregnant woman with a history of obstetric anal sphincter injury during childbirth has no symptoms of fecal incontinence before her next delivery or no obvious abnormalities on endonal ultrasonography or anal manometry, it is proposed that she consider a vaginal

delivery.

Strength of Recommendation: Weak, (Consensus Rate: 100%), Level of Evidence: B

$\bullet$ If a pregnant woman with a history of anal obstetric anal sphincter injury during childbirth has mild symptoms of fecal incontinence before her next delivery, it is proposed that she undergo endoanal ultrasonography and anal manometry if possible, and consider a planned cesarean section if obvious abnormalities are found to avoid worsening of fecal incontinence.

Strength of Recommendation: Weak, (Consensus Rate: 100%), Level of Evidence: B

* If a pregnant woman with a history of obstetric anal sphincter injury during childbirth has severe symptoms of fecal incontinence before the next delivery, it is proposed that she consider a vaginal delivery because it is unlikely that the fecal incontinence will be further aggravated by a vaginal delivery.

Strength of Recommendation: Weak, (Consensus Rate: 100%), Level of Evidence: B

The guideline published by the Royal College of Obstetri-cians and Gynaecologists[208] recommends that women with a history of OASIS should thoroughly discuss the mode of their next delivery with their physician or special-ist. This is to avoid aggravation of fecal incontinence (FI) symptoms associated with recurrent OASIS by subsequent vaginal delivery and to avoid unnecessary cesarean section. In such cases, it is necessary to consider FI symptoms, en-doalal ultrasonography findings, and anal manometry as well as obstetric conditions and the wishes of the pregnant woman.

In women with a history of OASIS, its recurrence rate at the subsequent vaginal delivery has been reported to be 4.4%-9.0%[386-388]. Edozien et al.[389] investigated the course of 639,402 primiparas using the UK health insurance medical database and found that 24.2% of the women with a history of OASIS at the first vaginal delivery delivered by cesarean section at the second delivery, whereas only 1.5% of the women without a history of OASIS delivered by cesarean section at the second delivery. In addition, the incidence of OASIS in women who delivered by vaginal delivery at the second delivery was 5.5 times significantly higher among pregnant women with a history of OASIS (7.2%) than that among pregnant women without a history of OASIS (1.3%). Jango et al.[390] studied 1,490 women with a history of OASIS at their first vaginal delivery who delivered by vaginal delivery at their second delivery and found that OASIS recurred at the second delivery in 106 (7.1%) of them. In addition, the proportion of women with FI ≥5 years after the second delivery was significantly higher in those with recurrent OASIS (25 women, 23.6%) than in those without recurrent OASIS (182 women, 13.2%). However, a

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systematic review (14 papers, 977 patients)[391] examining the effect of mode of next delivery in women with a history of OASIS showed no significant association between mode of subsequent delivery and anal incontinence. Therefore, anal incontinence may develop or aggravate when pregnant women with a history of OASIS give birth by vaginal delivery, but it is inconclusive whether the prevalence of anal incontinence will increase significantly.

Scheer et al.[386] prospectively evaluated 59 pregnant women with a history of OASIS by adopting a protocol in which cesarean section was performed in cases where endoanal ultrasonography showed an anal sphincter defect ≥ 30° and a voluntary contraction pressure increase of <20 mmHg, whereas vaginal delivery was performed in all other cases. As a result, 47 women were assigned to vaginal delivery and 12 to cesarean section; however, 3 women in the cesarean section group preferred vaginal delivery, five women in the vaginal delivery group preferred cesarean section, and 4 women had emergency cesarean section. Finally, 41 women underwent vaginal delivery, whereas 18 underwent cesarean section. Evaluation at 13 weeks after delivery showed that OASIS recurred in three women (7.3%) in the vaginal delivery group, but overall, there was no significant change in FI symptoms, QOL, and anal pressure. The guideline published by the Royal College of Obstetricians and Gynaecologists[208], also adopting the protocol of Scheer et al., recommends performing endoanal ultrasonography and anal manometry if FI symptoms persist in pregnant women with a history of OASIS and then considering a planned cesarean section if the abnormalities described in the protocol of Scheer et al. are observed. In contrast, if a pregnant woman has a history of OASIS but no symptoms of FI and no abnormalities described in the protocol of Scheer et al. are detected by endoanal ultrasonography and anal manometry, a vaginal delivery is recommended.

Several studies have validated this protocol[392-394]. Karmarkar et al.[392] proposed vaginal delivery in 26 cases and planned cesarean section in 24 cases based on the guideline published by the Royal College of Obstetricians and Gynaecologists for 50 pregnant women with a history of OASIS. Evaluation at 8-12 weeks after the subsequent delivery revealed that none of the women who had undergone vaginal delivery as planned complained of FI after delivery. Jordan et al.[393] also proposed the mode of delivery for 122 pregnant women with a history of OASIS based on the guideline published by the Royal College of Obstetricians and Gynaecologists, evaluated the symptoms of FI using the St. Mark's Score, and performed endoanal ultra-sonography and anal manometry before and 3 months after the subsequent delivery. As a result, in 99 women who had undergone vaginal delivery, the symptoms of FI did not aggravate, and ultrasonography did not reveal any aggravation of anal sphincter injury. However, voluntary contraction

pressure significantly decreased from an average of 92 mmHg to 50 mmHg. Jordan et al.[393] also presented an algorithm in which they listed three options for women with a history of OASIS who have persistent FI symptoms and whose endonal ultrasonography and anal manometry findings reveal obvious abnormalities. As the first option, cesear-ean delivery is recommended if the FI symptoms are mild. As the second option, if the FI symptoms are severe, vaginal delivery is recommended if the patient wishes to give birth to a second child, based on the expectation that it is unlikely for FI symptoms to further aggravate. As the third option, anal sphincteroplasty is recommended if the patient does not wish to give birth to any more children. In addition, the In-continence 6th Edition[395] also adopted the algorithm of Jordan et al. However, for the second option, the patient will experience severe FI in the subsequent pregnancy and delivery, but this could be avoided by undergoing anal sphincteroplasty before the next pregnancy to improve FI and re-considering and selecting the mode of delivery based on FI symptoms and examination results.

In contrast, Abramowitz et al.[396] conducted an RCT in which 222 pregnant women who had grade 3 OASIS but without FI were randomly assigned to the vaginal delivery group (112 women) and the cesarean section group (110 women). Evaluation after 6 months from the delivery revealed that aggravation of anal sphincter injury as shown by ultrasonography occurred in significantly more women in the vaginal delivery group (22.4%) than in the cesarean section group (only 2.2%). However, the median St. Mark's Score was one point for both groups, indicating no significant difference. Therefore, it was concluded that cesarean section should not be uniformly recommended to patients with a history of OASIS but no symptoms of FI.

In addition, in clinical studies on modes of subsequent delivery for pregnant women with a history of OASIS, endoanal ultrasonography and anal manometry are often performed. However, it is currently not possible to perform both tests on all eligible pregnant women in Japan because only a limited number of facilities can perform both tests. Therefore, when it is not possible to perform both tests, the pregnant women and their physicians should thoroughly discuss the mode of their subsequent delivery, considering the presence or absence and severity of FI symptoms as well as obstetric conditions and the wishes of the pregnant woman.

2. Sacral neuromodulation (SNM)

Statement

$\bullet$ Sacral neuromodulation is recommended for patients in whom conservative therapies are ineffective or not feasible.

Strength of Recommendation: Strong (Consensus Rate: 90.9%), Level of Evidence: A

Abstract

Sacral neuromodulation (SNM) is a treatment designed to

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improve various pelvic floor dysfunctions, including defecation disorders, such as fecal incontinence (FI) and constipation; lower urinary tract dysfunction, such as urinary incontinence and difficulty urinating; and pelvic floor dysfunction, including chronic pelvic pain, by electrically stimulating the sacral nerve. SNM involves two stages: the first surgical procedure places a stimulation lead, allowing for evaluation of efficacy over a test stimulation period of approximately 2 weeks. In cases where the test is effective, a second procedure implants a nerve stimulator, while the stimulation lead is removed if the test is ineffective. A key feature of SNM is its ability to select effective cases through this test stimulation and its reversibility, which allows patients to return to their original state without worsening symptoms if the treatment is not effective. SNM has demonstrated excellent short- and long-term outcomes for FI and is indicated for all patients in whom conservative therapies have failed and test stimulation is safe to perform. Its adverse events include pain and infection at the implantation site. Some examinations and treatments are contraindicated for concomitant use with SNM; thus, surgeons performing SNM are required to attend a seminar.

Commentary

In Japan, this surgical treatment has been covered by insurance for FI since April 2014 and for refractory overactive bladder since September 2017, with insurance points allocated to each of the two surgical procedures: stimulation lead placement and stimulator implantation. Although a relatively new surgical treatment in Japan, it has a long history globally. The efficacy of this treatment for treating urinary incontinence was first reported in the United States in 1982, and the implantation of a stimulator for treating FI was first performed in Europe in 1995[397,398]. SNM has already been approved as a treatment device for FI in Europe and the United States, and as of April 2021, approximately 345,000 cases of pelvic floor dysfunction have been treated with SNM worldwide.

The efficacy of SNM for FI has been demonstrated in favorable short-term [399,400] and long-term outcomes[92,401,402]. In a US clinical trial [399], test stimulation was performed in 133 patients, and the stimulator was implanted in 120 patients (90%). Of these, 106 patients were evaluable after 1 year, and 88 (83%) were successfully treated (with a reduction of >50% in FI; same below), and 43 (41%) achieved complete continence, with significant improvement in the FIQL Scale. A study on 76 patients in this clinical trial who had undergone implantation for >5 years revealed good long-term outcomes with a success rate of 89% and complete continence maintained in 36% of patients. A study on the long-term outcomes in 235 patients in the UK showed that favorable outcomes were maintained 9 years after surgery and 12 years after surgery when a telephone survey was conducted, with complete continence

achieved in 21 (12.5%) and 12 (10.4%) patients, respectively[401]. Furthermore, in a study of 325 patients in the Netherlands, 52.7% of the patients maintained efficacy over a mean follow-up period of 7.1 years, showing good long-term outcomes but no improvement in QOL[402]. In the first Japanese multicenter study[400] reported in 2014, test stimulation was performed in 22 patients, and implantation was performed in 21 patients (95%). Of these, 18 (86%) were successfully treated after 6 months and 4 (19%) achieved complete continence.

Regarding the cause-specific outcomes of SNM for FI, good outcomes with a success rate of 75% were reported for idiopathic FI without anal sphincter injury[405]; however, even patients with anal sphincter injury achieved outcomes comparable to those in patients without anal sphincter injury[406]. In addition, in a systematic review[407] on the efficacy of SNM for LARS, a defecation disorder including FI after rectal cancer surgery, the stimulator was implanted in 34 (79%) of 43 patients who had undergone test stimulation, and symptoms improved in 32 (74%) of the patients. Furthermore, a meta-analysis on LARS showed significant improvement in both the CCFIS and LARS scores[408], and efficacy comparable to that on other causes of FI was achieved[408]. Moreover, the efficacy of SNM for FI following surgery for rectal prolapse[409], Crohn's disease[410], ulcerative colitis[411], and cauda equina syndrome[412] has also been reported. In other words, it is not possible to determine the indication for SNM based on the cause of FI. SNM is indicated for all patients in whom conservative therapies are ineffective and test stimulation can be safely performed.

The precise mechanism of SNM is not fully understood but is considered multifactorial. By electrically stimulating the sacral nerve plexus, it induces contraction of the anal sphincter and levator ani muscles via the pudendal nerve, influences the sensory and autonomic nerves of the colorectal region via the pelvic plexus, and exerts effects on the central nervous system via the spinal cord[413].

Approximately 40% of patients with FI have urinary incontinence, and approximately 25% of patients with urinary incontinence have FI[414]. Because SNM is an effective treatment for both types of incontinence, patients with double incontinence can expect simultaneous improvement of both symptoms. According to a systematic review (6 papers, 113 patients)[414], when SNM was performed on patients with double incontinence, the average improvement rate was

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||Advantage|Disadvantage| |---|---|---| |Anal sphincteroplasty|Enables morphological repair of the anal sphincter and perineum|Long-term deterioration of outcomes| |Sacral neuromodulation|Enables evaluation of efficacy with test stimulationA reversible treatment methodGood long-term outcomesPatient can turn on/off and adjust intensity|Contraindication for MRI scans of areas other than the head(Patients with lead implantation after November 2022 can undergo whole-body MRI scans under certain conditions)Two hospitalizations for treatment are necessaryImplantation of a foreign object in the bodyStimulator needs to be replaced (approximately every 5 years for conventional nonchargeable stimulators and approximately every 15 years for rechargeable stimulators introduced in February 2023)Inability to undertake hyperthermia (such as diather-my)High medical expenses|

87% (44%-100%) for FI, 67% (20%-100%) for urinary in-continence, and 62% (20%-100%) for double incontinence.

With respect to adverse events, pain at the implantation site was the most common at approximately 25%, followed by infection at the implantation site at approximately 10%[399,402]. In a US clinical trial[399], modification, replacement, and removal of the stimulator were performed in 6%, 7%, and 11% of patients, respectively. However, most of the other adverse events could be managed with conservative treatment, program adjustments, and follow-up.

Some examinations and treatments are contraindicated for concomitant use with SNM. Previously, MRI scans were contraindicated for patients with SNM except for the head. However, MRI-compatible devices became available in November 2022, allowing whole-body 1.5- and 3.0-T MRI scans under specific conditions. Rechargeable stimulators, introduced in February 2023, have a lifespan of approximately 15 years with proper management, compared with 5 years for conventional stimulators requiring surgical replacement. In contrast, hyperthermia (diathermy) using an ultra-shortwave or microwave treatment device remains contrain-dicated due to the risk of tissue damage and damage to the stimulator resulting from heat generation at the electrode implantation site.

Regarding the statement at the beginning, "We recommend sacral neuromodulation for patients in whom conservative therapies are ineffective or not feasible," there were opinions in favor of recommending it as a weak recommendation in the vote to determine the strength of recommendation among the Guideline Preparation Committee.

CQ4. Which of the following should be applied first for fecal incontinence caused by laceration of the anal sphincter: anal sphincteroplasty or sacral neuromodulation?

Statement

$\bullet$ Because it remains unclear which treatment should be

prioritized, the decision should be made on a case-by-case basis after thoroughly explaining the characteristics, advantages, disadvantages, and expected outcomes of each treatment method and obtaining informed consent from the patient.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C Commentary

Currently, there are no reports of RCTs of anal sphincteroplasty and SNM for laceration of the anal sphincter. Thus, the optimal first-line treatment remains a subject of debate. Therefore, the characteristics as well as advantages and disadvantages, including treatment outcomes, of each treatment method (Table 12) should be fully explained to the patient before selecting and agreeing on a treatment method on a case-by-case basis in consultation with the patient based on their condition, medical status, and wishes.

In a study on SNM in 91 patients without laceration of the anal sphincter and 54 patients with a mean 105° laceration of the anal sphincter[415], both groups showed significant improvement in fiscal incontinence (FI) scores (CCFIS and St. Mark's Score) 12 months after surgery, indicating similar efficacy. In addition, a prospective study on SNM in 21 patients with laceration of the anal sphincter up to 120° and 32 patients without laceration[406] also showed comparable efficacy in CCFIS and FIQL over a 12-month follow-up period. In a systematic review of SNM for patients with anal sphincter lacerations[416], the CCFIS decreased from 16.5 to 3.8. However, nine of the studies included in the review were retrospective, excluding the aforementioned prospective study, indicating a low level of evidence. Furthermore, in a study comparing treatment outcomes in 13 women who underwent anal sphincteroplasty and 13 women who underwent SNM for FI caused by laceration of the anal sphincter, with matching patient backgrounds[417], the

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CCFIS improved significantly only in the SNM group.

In contrast, the long-term outcomes of anal sphinctero-plasty for laceration of the anal sphincter remain at an effi-cacy rate of 10%-46% 5 years after surgery[8,418]. Because the evaluation method is not constant, it is difficult to sim-ply compare the surgical outcomes of anal sphincteroplasty with those of SNM. However, the long-term outcomes (in a median period of 9 years and 3 months) of 160 patients who had undergone anal sphincteroplasty showed that the per-centage of patients with a reduction of ≥50% in the fre-quency of FI (patients judged to have been successfully treated by SNM) was 60%, which was comparable to the long-term outcomes of SNM[419].

In a study on the evolution of the two treatment methods at six facilities in Europe and the United States[420], 284 cases of SNM and 177 cases of anal sphincteroplasty had been performed for laceration of the anal sphincter from 2000 to 2013. To examine the evolution of both treatment methods, we compared the rates of each procedure between the early period (2000-2003) and the late period (2007-2010) and found that the number of patients who underwent SNM first increased significantly from 29% in the early period to 89% in the late period. In addition, a single-year comparison showed that in 2000, 95.3% of patients underwent anal sphincteroplasty first, but in 2013, 82.6% of patients underwent SNM first, indicating a significant paradigm shift in approximately 10 years. In contrast, some reports have sounded the alarm at the results of this study and advocated the importance of anal sphincteroplasty, a simple surgical treatment that morphologically repairs the anal sphincter without implanting a foreign object in the body, for young patients with delivery trauma accompanied by a 90°-180° laceration of the anal sphincter[421], but this remains controversial. One of the advantages of SNM is its reversibility, in that it does not morphologically change the anal sphincter itself, and it can be restored to the preoperative state by removing the stimulation lead if the test stimulation is ineffective. In addition, although MRI scans of areas other than the head had been previously contraindicated for SNM, MRI-compatible leads have become available since November 2022, reducing the challenges to introducing this treatment. In contrast, the inability to undertake hyperthermia (diathermy) continues to be cited as a disadvantage. In conclusion, the choice between anal sphincteroplasty and SNM should be based on a comprehensive evaluation of their respective treatment outcomes, characteristics, and the patient's individual circumstances.

3. Stoma construction

Statement $\bullet$ Stoma construction is proposed for patients with fecal incontinence in whom other treatments are ineffective or not feasible. Strength of Recommendation: Weak (Consensus Rate:

100%), Level of Evidence: B

Abstract

In recent years, advances in stoma appliances and environmental maintenance, such as management guidance by certified nurses in wound, ostomy, and continence nursing, have improved the QoL of ostomates, making stoma construction a surgical treatment option for fecal incontinence (FI). This procedure is generally considered to be the last resort for severe FI, but it is the simplest and most fundamental solution for FI if the patient can accept the psychological issue of body image being different from others.

Commentary

With the publication of the first edition of these guidelines and the explicit inclusion of stoma construction in the surgical treatment algorithm[422], the challenges for patients and medical professionals in choosing stoma construction as a treatment for FI have been lowered. Therefore, when necessary, medical professionals should provide patients with information on stoma construction as a surgical treatment option for FI. It is important to confirm each patient's acceptance of the psychological issues related to body image due to having a stoma[423], as these issues can significantly affect their QoL.

In stoma construction for FI, the anal side of the sigmoid colon is usually closed while the anus is left intact, and an end stoma is constructed using the oral side of the sigmoid colon. However, in this case, the patient may require rectal amputation in the future due to diversion colitis of the remaining empty colon[424]. Thus, this possibility must be fully explained to the patient before stoma construction. When constructing a stoma, it is the surgeon's responsibility to employ techniques that ensure the stoma is well-formed, of adequate height, and positioned appropriately. This reduces the risk of stoma-related complications, facilitates easier stoma care, and enhances the patient's QoL[425].

Advances in ostomy appliances and progress in environmental maintenance, such as guidance by certified nurses in wound, ostomy, and continence nursing[426], have improved the QoL of ostomates. A comparison of QoL using the SF-36 between 71 patients with FI and 39 ostomates who had undergone stoma construction because of rectal cancer, colocic diverticulosis, or FI showed that ostomates had significantly better QoL in terms of social functioning than that of patients with FI[427]. In addition, according to a questionnaire survey of 69 ostomates who had undergone stoma construction as a treatment for severe FI[428], QoL was better after stoma construction than before stoma construction.

Several studies have compared QoL between patients who have FI after anus-preserving surgery for rectal cancer and ostomates who had undergone permanent stoma construction following rectal amputation for rectal cancer, but no reports have found significant differences in overall QoL between the two groups[429,430]. A systematic review on follow-ups

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of ostomates reported improvement in overall QoL over time[431]. Patients with spinal cord injury who underwent stoma construction for FI also demonstrated an improvement in QoL[432,433]. As described above, the construction of a stoma for treating FI may improve QoL; however, it should be noted that treatment outcomes and evidence regarding QoL differ depending on the pathology of FI.

If FI does not improve adequately with initial treatment, it is important to refer the patient to a specialized medical institution for FI [434]. If the symptoms of FI do not adequately improve with conservative therapies at a specialized medical institution, stoma construction is an option. In such cases, it is desirable to have a team of medical care in place that can provide decision-making support regarding stoma construction [435].

However, although the construction of a stoma for treating FI can relieve the problems and concerns caused by FI, daily stoma care becomes necessary, and stoma-related complications may arise. In this regard, the "Manual of Prevention, Treatment and Care of Intestinal Stoma-Related Complications"[436] published by the Japanese Society of Stoma and Continence Rehabilitation and the Japan Society of Coloproctology, is useful. Because stoma-related complications lead to a decline in QoL, it is necessary to prevent them from becoming severe by appropriate assessment and intervention using assessment tools, such as ABCD-Stoma® published by the Japanese Society of Wound, Ostomy and Continence Management[437]. When selecting stoma construction as a treatment for FI, it is important to strive to improve the QoL of the ostomate.

B. Special surgical treatment

1. Antegrade continence enema (ACE) Statement

$\bullet$ Although ACE has some morbidities, such as wound infection and postoperative stenosis, it is a useful treatment for fecal incontinence because it can be performed in a shorter time with less lavage fluid than transanal irrigation.

Abstract

ACE is a treatment to improve fecal incontinence (FI) that involves keeping the colon empty with antegrade lavage via an appendiceal or cecal fistula created by laparotomy, laparoscopic surgery, or endoscopic placement[438]. In cases after appendicectomy, a surgical technique called ileal neoappendicostomy has been reported, in which the ileum is dissected at 6 cm from the distal end of the ileum. The oral end is anastomosed to the ascending colon, and the anal side of the ileum, which has a narrow diameter, is used to substitute for the appendix[439].

Regarding transanal irrigation, ACE is indicated for severe defecation disorders, such as frequent bowel movements and severe FI, as bowel lavage is laborious and time-consuming.

Compared with transanal irrigation, the advantages of ACE are that less amount of lavage fluid needs to be infused and a shorter time is required for bowel lavage. However, minimally invasive surgery is still required. Defecation does not occur through the cecal fistula; however, body image concerns remain, although these are less severe than those associated with a stoma.

Commentary

ACE was first reported by Malone et al. in the UK in 1990[440] and was mainly performed for neurogenic bowel dysfunction in children[441]. Subsequently, it has been applied for the treatment of FI and constipation in adults[442].

Long-term outcomes regarding the assessment of defecation function, social life, and QoL showed significant improvements in FI as well as in chronic constipation and neurogenic bowel dysfunction[443]. In a systematic review of studies on adults[444], 78%-100% of patients continued ACE in a follow-up period of 22.5-48 months. Additionally, a retrospective study of 75 patients showed that 64 (85%) patients continued ACE during a median follow-up period of 48 months, with the Wexner Score significantly improving from 14.3 preoperatively to 3.4 postoperatively[445]. In patients who discontinued ACE, the reasons for ACE discontinuation were abdominal pain during the procedure and prolonged FI.

In a systematic review of six studies on adults and two on children regarding ileal neoappendiceal fistula, improvement in symptoms of FI and constipation was observed in all studies, and improvement in QoL was observed in five studies[446].

The most common early postoperative complication is wound infection at 45%[447], and other early complications, such as intestinal perforation, have also been reported[443]. Late complications include increased incidence of postoperative stenosis[443,446], and cases have been reported in which bougie dilatation or reconstruction was performed[448]. With ileal neoappendiceal fistulas, there is also a high incidence of stenosis, necrosis, and suture failure at the ileal-ascending colon anastomosis site[446]. However, these complications are primarily attributed to appendiceal fistula, and the use of gastrostomy kits, though off-label, has shown promise in significantly reducing these issues.

Bowel lavage is often performed daily or every alternate day, and when not in use, the mucous fistula is covered with a dressing and the external fistula is plugged with the button of the gastrostomy kit. Side effects of bowel lavage include pain during catheter insertion, nausea, malaise, and skin problems[443].

2. Graciloplasty

Statement

$\bullet$ Graciloplasty is a surgical treatment that should be performed in a limited number of specialized facilities because of the complexity of the surgical procedure

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and the need for numerous operations to master the surgical technique.

Abstract

In graciloplasty, the gracilis muscle is mobilized and wrapped around the canal canal, and the tendon on the distal side of the gracilis is sewn to the opposite sciatic bone to close the anal canal with moderate pressure to maintain fecal continence [449]. This treatment is often selected for patients with severe fecal incontinence (FI) in whom other surgical treatments are ineffective, and stoma construction is the only alternative.

Commentary

This surgical procedure was first reported in 1952 for FI in children[450] and was subsequently applied to the treatment of FI in adults[451]. There are two types of surgery: adynamic graciloplasty (AG)[452], which simply includes muscle grafting, and dynamic graciloplasty (DG)[451], which refers to the muscle grafting with an electrical stimulator. Conventionally, to obtain good results with this treatment, DG was considered necessary to transform gracilis muscles from type II (fast-twitch) fibers prone to fatigue into type I (slow-twitch) fibers capable of sustained contraction, similar to the external anal sphincter. However, the advent of sacral neuromodulation rendered the use of electrical stimulators in DG impractical, leading to its decline in Europe and the United States. However, the effect of DG could be obtained in AG by performing transanal electrical stimulation for 6 months after the surgery[453].

Regarding the efficacy of this treatment, a multicenter study on DG in 123 patients with FI[451] reported that DG was efficacious in 81 patients (66%) after 18 months, and a systematic review of DG[454] revealed that DG was effective in 42%-85% of patients. In addition, among the 31 patients who underwent DG after abdominoperineal rectal amputation for rectal cancer, defecation function could be evaluated postoperatively in 26 patients, of which 22 (71%) maintained fecal continence in a median follow-up period of 37 months[455]. In a study reported from Japan[449], 15 patients with severe FI underwent graciloplasty (12 cases of AG and three cases of DG), and excluding three patients in whom a stoma was constructed, 12 patients were evaluated, of which 8 (67%) maintained fecal continence of Kirwan classification grade 2 (gas incontinence only) or higher after surgery. In an observational study of 17 patients who underwent AG, 13 (76.5%) achieved fecal continence with postoperative CCFIS of ≤2[456]. Furthermore, an evaluation of 31 patients who underwent AG 1 year after surgery revealed that the effect was maintained in 25 (81%) of the patients[457].

With respect to complications, in a multicenter study of 123 patients[451], complications occurred 189 times in 91 patients (74%), and surgery for complications was performed in 49 patients (40%). A systematic review of

DG[454] reported complications at an average of 1.12 times per patient with a surgery-related mortality of 2%. In addition, cases of stoma construction due to rectal perforation and rectovaginal fistula have been reported in AG[457].

As described above, graciloplasty is one of the most complex and difficult surgeries for FI, and numerous operations are required to master the surgical technique; thus, it should only be performed in a limited number of specialized facilities.

3. Ventral rectopexy

Statement

$\bullet$ Ventral rectopexy is effective for treating passive fecal incontinence caused by rectal intussusception, rectal prolapse, or rectocele. However, consideration should be given to the potential risk of mesh-related complications.

Abstract

VR is a treatment aimed at improving symptoms of fecal incontinence (FI) and defecation disorder by straightening and fixing the rectum with a mesh attached to the ventral side of the lower rectum, thereby repairing rectal intussusception, rectal prolapse, and rectocele. Patients with passive FI caused by rectal intussusception or rectocele who do not respond adequately to maximal conservative therapies can be considered for this treatment. In addition, eligible patients should be carefully selected by further tests, such as defecography.

VR has been reported to improve FI in 62.5% of patients, making it an effective treatment. However, the incidence of mesh-related complications is 1.7%, and these complications often require surgical intervention. Therefore, obtaining a thoroughly informed consent is crucial before surgery.

Commentary

VR involves an abdominal approach in which the perito-neum on the right side of the rectum is incised from the sacral promontory to the rectouterine (or rectovesical) fossa. The rectovaginal (or rectoprostatic) septum is dissected down to the pelvic floor, and a mesh is secured to the ventral side of the lower rectum and sacral promontory to stabilize the rectum. VR was first reported by D'Hoore et al.[458] in 2004 as a surgery for treating rectal prolapse and is characterized by the preservation of the autonomic nerves in the dorsal rectum. It is commonly indicated for female patients with FI caused by rectal intussusception, rectal prolapse, or rectocele.

Recent studies suggest that rectal intussusception may be a precursor lesion of rectal prolapse, and their pathophysiology is considered to be common[459]. Although the mechanism by which rectal intussusception causes FI is unclear, it has been suggested that the rectoanal inhibitory reflex is induced[451], and resting anal canal pressure is decreased[242]. Although the mechanism by which rectocele causes FI is unclear, a possible mechanism is that stool that

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is not completely expelled during defecation and remains in the rectocele leaks out after defecation[243].

Patients with FI unresponsive to maximal conservative therapies and severe rectal intussusception (grade III or IV based on the Oxford classification) identified on defecography may benefit from VR. However, the type of FI for which VR is indicated is passive FI, particularly following defecation, rather than urge FI. VR is often performed laparoscopically and uses mesh; thus, it is called laparoscopic ventral mesh rectopexy (LVMR).

In Japan, short-term outcomes of LVMR in 34 patients with severe rectal intussusception and FI revealed a ≥50% reduction in incontinence frequency in 31 patients (91%) at 1 year postoperatively[460]. In terms of the mid- to long-term outcomes of 46 patients with rectal prolapse at the same facility, their FISI scores significantly improved from 34 to 12 in the 3 months after surgery, and 10 patients had a FISI score of 7, indicating good outcomes, 5 years after surgery[461].

In the United Kingdom, LVMR was performed in 72 patients with severe rectal intussusception (grade III in 26 patients and grade IV in 46 patients) accompanied by FI, and their FISI score significantly improved from 31 to 15 in 1 year after surgery[241]. Postoperative complications that have been reported included dysuria in seven patients (9.7%) and exposure of the mesh to the vagina, causing infection and requiring removal, in one patient[241].

In addition, in a report on the long-term outcomes in 848 patients in the United Kingdom[462], 478 patients (56%) responded to a telephone questionnaire in a median postoperative follow-up period of 7 years. Of these, 104 (22%) had symptoms of FI, and evaluation of the degree of improvement in FI symptoms after LVMR using the Likert scale revealed improvement in about 2/3 of the patients, with improvement in 70 patients (67%), no change in 20 (19%), and exacerbation in 14 (14%). In contrast, postoperative new pelvic pain was reported in six patients (8%). Furthermore, sexual function improved in 11%, remained unchanged in 71%, and exacerbated in 18%. Therefore, considering the possibilities of pelvic pain and sexual dysfunction, the authors concluded that informed consent must be obtained before surgery.

A comparison of robot-assisted LVMR (187 patients) and conventional laparoscopic surgery (214 patients) showed better outcomes in CCFIS and FI symptoms for robot-assisted surgery at 3 years postoperatively[463]. Postoperative complications reported included new pelvic pain at a high incidence (31.8% in robot-assisted surgery, 11.8% in laparoscopy), dysuria (19.1% in robot-assisted surgery and 14.7% in laparoscopy), and mesh exposure to the vagina (one case in robot-assisted surgery).

The outcomes of SNM are reported to be poor in patients with severe rectal intussusception[464]. In the study, 106 pa-

patients with FI for whom SNM was indicated underwent defecography, and severe rectal intussusception was observed in 36 patients (34%). When the outcomes of SNM were compared between the group with severe rectal intussusception and the group without, the success rate of test stimulation was 69% in the group with severe rectal intussusception, which was significantly lower than that in the group without severe rectal intussusception at 86%. In addition, a nerve stimulator was implanted in patients with successful test stimulation, and the median FISI score after 1 year significantly improved from 38 to 34 in the group with severe rectal intussusception and significantly improved from 37 to 23 in the group without severe rectal intussusception, and the treatment success rate was also significantly lower in the group with severe rectal intussusception at 16% than that in the group without severe rectal intussusception at 52%. Therefore, it may be better to perform VR before SNM in patients with passive FI accompanied by severe recat tal intussusception, and it may also be better to consider performing VR in patients for whom SNM is ineffective.

A systematic review of 10 studies involving 1,147 patients found a 62.5% improvement in FI following VR, with a symptom recurrence rate of 7.3%. Complications included urinary tract and wound infections, with mesh-related complications occurring in 1.1% of cases.

Absorbable mesh has also been used to reduce mesh-related complications, such as mesh exposure to the vaginal or rectal surface and infection. A systematic review (eight studies, 3,956 patients)[465] comparing nonabsorbable (synthetic) and absorbable (biological) meshes in LVMR revealed an overall complication rate of 26.2%, with mesh-related complications occurring in 67 patients (1.7%) after 1.7-124 months. The incidence of mesh-related complications was 1.9% (66/3,517 patients) for nonabsorbable mesh, which was significantly higher than that for absorbable mesh at 0.2% (1/439 patients). All mesh-related complications were of Clavien-Dind classification grade III-b, requiring surgical treatment, such as low anterior resection and stoma construction, but there were no deaths.

As described above, LV may be effective for treating FI possibly caused by rectal intussusception, and an expert consensus conference[466] also proposed that “patients with severe rectal intussusception of grade III or IV whose symptoms of FI or defecation disorder do not improve adequately with maximal conservative therapies are relatively indicated for VR.” However, postoperative pelvic pain, sexual dysfunction, and serious mesh-related complications, even at low incidence, are concerning. Therefore, the Incontinence 6th Edition[467], despite stating that “VR may improve FI in carefully selected patients,” rated this treatment weak in strength of recommendation at C. In addition, VR is not even included as a treatment for FI in the latest European guideline[69] on the management of FI and the ASCRS'

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Clinical Practice Guidelines[64]. Therefore, in our guidelines, VR is included as a special surgical treatment rather than a standard treatment for FI, and it is a subject for future research.

C. Other surgical treatments

1. Biomaterial injection

Statement

$\bullet$ Biomaterial injection may be useful as a minimally invasive treatment for passive fecal incontinence caused by a decrease in resting canal canal pressure. Although some injection substances have been approved in Europe and the United States, they have not been approved in Japan.

Abstract

Biomaterial injection is a treatment to improve fecal incontinence (FI) by injecting a biocompatible material into the anal submucosa and between the external and internal anal sphincters to cause bulging, appropriately closing the anal canal. It may be useful for treating passive FI caused by decreased resting anal canal pressure resulting from poor internal anal sphincter function. Sphinxkeeper™ is approved in the EU, and Solesta® is approved in the United States as biocompatible materials for injection, and they have been reported to be effective in improving passive FI. However, they have not been approved in Japan yet.

Commentary

The material selected to be injected should be biocompatible, nonallergenic, easy to inject, and non-tissue transferable. Because it was reported in 1993 that injecting polytetrafluoroethylene into the anal submucosa was effective in making FI disappear in 64% of patients[468], the use of various biocompatible materials has been reported[469]. However, the number of cases has been small, and complications, such as anal pain and ulceration, have been reported.

Gatekeeper™ and Sphinkeeper™ (THD, Correggio, Italy) are approved in the EU, and Solesta® (Salix, Raleigh, USA) is approved in the United States. Gatekeeper™ is a solid material made of polyacrylonitrile, which is injected under ultrasound guidance between the internal and external anal sphincters to close the anal canal. In a report of 14 patients with FI injected with Gatekeeper™[470], the mean frequency of FI improved from 7.1 times/week to 0.4 times/week, and the mean CCFIS improved from 12.7 to 5.1 in a mean follow-up period of 33.5 months. Sphinkeeper™ is an improved version of Gatekeeper™[471]. In an observational study of 42 patients, the CCFIS improved significantly from 12.0 to 7.6 after surgery, and 5 patients achieved complete continence[472].

Solesta®, which was approved in the United States in 2011, is a liquid material of dextranomer beads/stabilized sodium hyaluronate gel, which is injected in 1 mL doses in

four directions under the anal mucosa, 5 mm orally from the dentate line, to close the anal canal. In a double-blind study[473] with the sham group as control, evaluation after 6 months showed improvement of FI in 71 of 136 patients (52%) in the Solesta® group, with a significant difference, compared with 22 of 70 patients (31%) in the sham group. A 3-year follow-up report[474] of 136 patients who had received Solesta® in the double-blind study showed that the percentage of patients with a reduction of ≥50% in the frequency of FI (hereinafter referred to as success rate) was 52%, 57%, and 52% 6 months, 1 year, and 3 years after surgery, respectively, indicating good long-term outcomes. Complications reported included anal pain and injection site nodule in 2.3% of patients each and rectal bleeding in 1.5% of patients, but all were minor complications, and no serious complications occurred. Regarding further long-term outcomes, the frequency of FI decreased remarkably from a mean of 21.5 times/week before surgery to 10 times/week 1 year after surgery in 16 patients who received Solesta®. However, it returned to 26.5 times/week in 11 patients who could be followed up to 10 years after surgery[475]. In addition, the success rate was 56% 1 year after surgery, and 27% 10 years after surgery. As shown above, its long-term outcomes are poor; however, because Solesta® allows for additional injections, it may be possible to inject it again when FI recurs. In an observational study of 17 patients, the first dose of Solesta® was successful in 14 patients (83.3%). When the remaining three patients were treated with an additional dose 3 months later, all patients were successfully treated. Seven patients (41%) achieved complete continence 1 year after surgery, and the frequency of FI in the remaining 10 patients improved from an average of 6.4 times/week to 2.8 times/week[476].

Biomaterial injection appears to be effective in the treatment of mild passive FI caused by decreased resting anal canal pressure resulting from poor internal anal sphincter function. Although the success rate is not high, at approximately 50% and the long-term outcomes are poor, because Solesta® can be administered repeatedly, it may be possible to readminister it at recurrence. No serious complications have been reported, and biomaterial injection is a simple and minimally invasive treatment that can be performed in an outpatient setting. Thus, it is hoped that this treatment will be introduced in Japan in the future.

2. Anal sphincter regenerative therapy

Statement

$\bullet$ Anal sphincter regenerative therapy can serve as a minimally invasive treatment for fecal incontinence. It has not yet been approved in Europe and the United States, where its efficacy for treating fecal incontinence has been reported, nor has it been approved in Japan.

Abstract

Anal sphincter regenerative therapy is aimed at improving

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fecal incontinence (FI) symptoms by transplanting stem cells into the anal sphincter with reduced contractile function, thereby restoring its function. Although human clinical studies have been conducted in Europe and the United States, this therapy has not yet been approved for routine medical use in Japan.

Commentary

Previously, stem cell transplantation experiments have been conducted using rats as the animal model of anal sphincter dysfunction[477], and based on the results of these experiments, randomized human trials have been conducted overseas to investigate the efficacy of stem cell transplantation for anal sphincters with reduced contractile function. According to the latest review[478], there had been one case report[479], two pilot studies[480,481], one exploratory baseline study[482], and three RCTs[483-485] involving stem cell transplantation therapy in humans. In these seven studies, stem cell transplantation therapy for improving FI was performed on 90 humans. Furthermore, an additional RCT (158 patients)[486] was reported after the publication of the review.

The cells used were autologous myoblasts in six studies and allogenic human adipose-derived stromal/stem cells[483] as well as autologous adipose tissue-derived multipotent cells[485], respectively, in the remaining two studies. All these cells were transplanted into the external anal sphincter, including one case report in which the cells were also transplanted into the internal anal sphincter[479].

In the two reports involving the transplantation of adipose tissue-derived mesenchymal stem cells, no significant difference was observed in the degree of improvement in the CCFIS between the treatment and control groups[483,485]. Conversely, in the MIAS trial, a phase II study evaluating the efficacy of culturing autologous myoblasts harvested from the quadriceps muscle and then injecting and transplanting them into the external anal sphincter in 24 patients with FI, the median CCFIS after 6 months significantly decreased in both the injection and transplantation group and the placebo group. No significant difference was observed between the two groups. However, after 12 months, only the injection and transplantation group showed sustained improvement, whereas the effect disappeared in the placebo group. Consequently, the response rate after 12 months was significantly higher in the injection and transplantation group than in the placebo group (58% vs. 8%, p = 0.03)[484]. In an exploratory baseline study, researchers evaluated the effects of culturing autologous myoblasts harvested from the pectoral muscle. Subsequently, they injected and transplanted them into the external anal sphincter in 10 female patients with FI due to anal sphincter injury during childbirth. One year after treatment, FI symptoms and QoL improved significantly. Specifically, the frequency of FI decreased from an average of 8 times per week before surgery

to 0 times per week. Additionally, the CCFIS improved from 15.3 to 1.6, and the FIQL score increased from 2.8 to 4.0[481]. Moreover, in a study evaluating the same 10 patients 5 years later, the frequency of FI was an average of 0 times/week, the CCFIS was 0.7, and the FIQL score was 4.0, indicating that the improvement effect was maintained over the long term[487]. Furthermore, the same anal sphincter regenerative therapy was applied to 39 patients (including five men) with urge FI caused by external anal sphincter rupture and by impaired external anal sphincter function. One year after treatment, the frequency of FI had decreased by an average of 11 times/week compared with that before surgery, the CCFIS was reduced by an average of 17, and the success rate with a reduction of ≥50% in the frequency of FI was 79.5%[482]. More recently, an RCT[486] on this anal sphincter regenerative therapy has been reported. When the frequency of FI after 6 months was compared among a high-concentration group (75 patients), a low-concentration group (83 patients), and a placebo group (79 patients) using different concentrations of transplanted cells, the frequency of FI decreased in all three groups of the high-concentration group (reduction in frequency of FI: 4.8 times/week), the low-concentration group (4.3 times/week), and the placebo group (3.2 times/week). However, only the high-concentration group exhibited a significant decrease in FI frequency compared with the placebo group (p = 0.02). Additionally, a subgroup analysis of this therapy identified two factors that significantly improved FI: "a history of FI of ≥ 10 years" and "a greater amount of FI compared with minor leakage."

Currently, the optimal cell population for transplantation, the methods, and techniques for preparing the cells, and the necessary and sufficient number of cells have not yet been fully established; however, because cell injections and transplantation have been performed safely with no reports of serious complications, it is expected that this will become an important field in the treatment of FI in the future.

In summary, although no meta-analyses exist regarding anal sphincter regenerative therapy, the reviewed literature included four RCTs[483-486] and two reviews[477,478]. Thus, its level of evidence can be considered reasonably robust.

VI. Treatment for Fecal Incontinence in Special Conditions

A. Neurogenic and spinal cord diseases (Injuries), a more detailed description

Abstract

In patients with neurogenic or spinal cord diseases, stool tends to accumulate in the rectum, and it is not uncommon for the retained stool to overflow and leak. In other words,

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because constipation and fecal incontinence (FI) are two sides of the same coin, it is important to understand the patient's excretion cycle and guide them to go to the toilet at the right time. If spontaneous defecation is not possible, the anorectal region should be stimulated with fingers to induce defecation or the rectum should be emptied periodically by manual evacuation, suppositories, or enemas. Transanal irrigation improves the symptoms of constipation and FI as well as QoL in patients with spinal cord injury.

Commentary

Based on the onset mechanisms of neurogenic and spinal cord diseases, they are classified into congenital, traumatic, degenerative, ischemic, etc. Injuries to the nervous system and spinal cord often result in motor and sensory disturbances of the pelvic organs and pelvic floor, leading to difficulty in regulating bowel movements and causing constipation and FI. The frequency of FI by disease has been reported to be over 70% in patients with spinal cord injury and multiple sclerosis[46,79], over 34% in patients with spina bifida[488], and 24% in patients with Parkinson's disease[489].

In patients with spinal cord injury, rectal sensation is decreased or eliminated, and therefore, the urge to defecate is also decreased or eliminated. Thus, the patient will not go to the toilet if their defecation relies on the urge to defecate, and fecal impaction, in which a large amount of feces accumulates in the rectum, is likely to occur. In addition, spinal cord injury also causes characteristic defecation disorders depending on the site of injury. Injury above the conus medullaris (a caudal edge of the tapered spinal cord, usually located as high as the first lumbar vertebra) is characterized by persistent increased tone of the colonic wall and external anal sphincter, a condition called reflex bowel, leading to fecal impaction or overflow FI. In contrast, injury at the conus medullaris and cauda equina is characterized by a decrease in colonic peristals and persistent atonic external anal sphincter and levator ani, a condition called flaccid bowel, leading to passive FI[490]. For patients with spinal cord injury, constipation and FI are perceived to be more serious than mobility impairment[79], causing anxiety and resulting in a decline in QOL[491]. However, conventional treatment is mostly empirical with little evidence[337].

In the treatment of FI associated with neurogenic and spinal cord diseases, the following evaluations are required in addition to the usual evaluation of FI[492,493].

1 Medical history: Patient's wishes, QoL assessment, problems with moving to the toilet, dressing and undressing, behavior of caregivers, etc.

2 Physical findings: Cognitive function, severity of spastic paralysis of the upper and lower limbs, abdominal palpation, and rectal examination, working ability of hands and fingers, walking and ambulating ability, ability to hold sitting position, motor, sensation, and reflexes of

the anorectum, etc.

1. Conservative therapy

a. Initial treatment

1. Fiber-rich diet and adequate fluid intake

2. Stimulation of the anorectum and use of suppositories and enemas

3 Planned defecation (timely assistance or trigger for defecation)

4. Prescription of oral medications

5 Abdominal massage

6 Manual evacuation

Patients with neurogenic and spinal cord diseases tend to have stool accumulated in the rectum due to decreased activity and sensory and motor disturbances in the anorectal region. Initial treatment aims to completely empty the bowels by regularly guiding the patient to the toilet and providing defecation stimulation. The above procedures should be attempted in stages to empty the rectum in a way that is optimal for the patient. Fiber-rich diet and adequate fluid intake are the basics for improving stool consistency. Stimulation of the anorectal region by digital rectal examination or suppositories induces increased peristalsis of the left colon and defecation[494], and a study on the timing of defecation induction in patients with stroke found that inducing defecation in the morning was more effective than inducing it in the evening[495]. Although the mechanism is unknown, it has been suggested to be related to gastro-colonic reflexes induced after breakfast. Abdominal massage has been reported to improve constipation in patients with multiple sclerosis and spinal cord injury[496,497]. Patients with fecal impaction require removal of the fecal mass by manual evacuation. In a survey of patients with spinal cord injury at home, 56% of the patients underwent manual evacuation as defecation care[498]. For more information on care for FI in neurogenic and spinal cord diseases, please refer to IV-A-3.

#

1 Transanal irrigation

2. Biofeedback therapy

3 Anal insert device

4 Tibial nerve stimulation

When initial treatment is not effective, specialized treatment is indicated. The therapeutic concept for neurogenic bowel dysfunction associated with neurogenic and spinal cord diseases is illustrated in Figure 8. If the treatments at the lower level are not sufficiently effective, a stepwise esculation to higher-level treatments is recommended[499,500]. Specialized treatment is indicated when initial treatment is not effective. Transanal irrigation promotes defecation by injecting lukwern water into the rectum and left colon (see IV-B-3)[334]. In an RCT of patients with spinal cord injury, transanal irrigation significantly improved constipation, FI, and QOL compared with conservative therapies (corresponding to initial treatment in this section)[335]. Although there

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are few reports on BF therapy, it has been reported to improve FI in patients with less severe multiple sclerosis[501]. Other specialized treatments include an anal insert device (see IV-B-4-c), and TNS (see IV-B-4-a) has been reported to have improved FI caused by incomplete spinal cord injury[502].

2. Surgical treatment

1 Antegrade continence enema

2. Sacral neumodulation

3 Colostomy

The improvement rate of defecation disorders caused by spinal cord injury is said to be 63% with conservative therapies[503]; thus, surgical treatment may be an option when FI does not improve or when chronic severe constipation co-exists. ACE is a treatment that involves creating an appendiceal or cecal fistula and inserting a catheter through the site to perform antegrade lavage (see IV-C-2-a). When this treatment was applied to patients with spinal cord injury, FI or constipation improved in seven of eight patients[504]. For more information on sacral neuromodulation, please refer to IV-C-1-b and CQ5. Colostomy (see IV-C-1-c) reduced the time required for defecation care in patients with spinal cord injury and improved their QOL[505,506].

CQ5. Is sacral neuromodulation effective for the treatment of fecal incontinence caused by spinal cord injury?

Statement

$\bullet$ Sacral neuromodulation is proposed to be performed, as it may improve fecal incontinence caused by incomplete spinal cord injury.

Strength of Recommendation: Weak (Consensus Rate: 100%), Level of Evidence: C

Commentary

Sacral neuromodulation is a treatment that improves defecation disorders and lower urinary tract dysfunction by electrical stimulation of the sacral nerve (see IV-C-1-b). Among 11 patients with cauda equina syndrome, 5 of the 8 patients who responded positively to test stimulation received a stimulator implant, and all experienced improvements in fecal incontinence (FI)[412]. However, this treatment was effective for all three patients with complete spinal cord injury[507]. There were reports of improvement in FI in patients with incomplete spinal cord injury and spina bifida[508-512]. In one of the reports, 29 of 36 patients were implanted with a stimulator, and FI and QoL were improved in 28 patients[510]. Additionally, in a study involving 10 patients with incomplete paraplegia, pre-treatment control of defecation urge was limited to less than 1 minute in all cases. After treatment, some patients could control their defecation urges for up to 15 minutes, demonstrating significant improvement[511].

The above findings are based on papers published up to 2014, evaluated in the first edition of these guidelines, but there have been very few reports since 2015 on the efficacy

of this treatment for defecation disorders, including FI, caused by spinal cord injury. This lack of recent data is likely attributable to the previously reported limited efficacy for patients with spinal cord injury, which may have discouraged further studies. Nevertheless, in 2020, the efficacy of this treatment for neurogenic bowel disorder (NBD) in 41 patients with neurogenic bladder associated with defecation disorder was reported, with significant improvement in NBD scores and good long-term outcomes in 26 patients, suggesting the efficacy of this treatment for incomplete spinal cord injury [513].

B. Dementia

Abstract

For fecal incontinence (FI) due to dementia, the relationship between the patient's surroundings and FI should be analyzed, the defecation environment should be improved, and the patient should be guided to defecate at appropriate times based on their bowel diary or other information. In cases of FI or stool playing, it is important to respect the patient's self-esteem and to strive to build a good relationship with the patient.

Commentary

The pathophysiology of FI in patients with dementia includes cognitive dysfunctional FI, in which the patient defecates in a location that is not the toilet or in an inappropriate container as a result of behavioral abnormalities, and overflow FI, in which the patient is unable to void due to a lack of the urge to defecate or impaired judgment, resulting in leakage of feces that have filled the rectum[425,514,515]. Chronic FI is found approximately 50% of patients with dementia residing in elderly care facilities[14,516].

Symptoms of dementia are broadly classified into core symptoms (memory impairment, disorientation, aphasia, apraxia, agnosia, etc.) and behavioral and psychological symptoms of dementia (BPSD). BPSD consists of behavioral symptoms (verbal abuse/violence, wandering, rejection, deinhibition, FI, etc.) and psychological symptoms (sense of anxiety, depression, emotional blunting, hallucination/delusion, etc.) [517]. BPSD is a secondary disorder caused by core symptoms, and physical, environmental, and psychosocial factors are deeply involved in the emergence of these symptoms; they may be triggered by an unfamiliar and uncomfortable environment or by the relationship with the caregiver [518]. The same is true for the triggers of FI and stool playing (mistaking stool for other objects, playing with stool in the toilet bowl, etc.), which are behavioral symptoms [515].

The treatment for FI in patients with dementia is the same as conservative therapies for general FI, but conducting a behavioral analysis of the patient with information collected from the patient, their family, and caregivers can help identify necessary measures. In other words, the relationship be-

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tween the patient's surroundings and FI should be examined (FI may occur if the patient does not know where the toilet is located). The location and circumstances in which FI occurs, the patient's reaction to FI, and the reactions of those around the patient should be observed. The discomfort felt after defecating in the diaper may cause the patient to get stool on their hands and rub it on their clothes while trying to remove the stool. Because patients with dementia often cannot express their urge to defecate and may express it as BPSD, such as wandering, a bowel diary or other records are useful for behavioral analysis[492,514]. It is also important to consider whether the caregiver's response is appropriate. If the caregiver gets angry or flames the patient with dementia for FI, the patient's self-esteem may be damaged, possibly leading to anger. In addition, behavioral symptoms, including FI, may become more severe as a form of rebellion against the caregiver's inappropriate response[515].

Based on the results of behavioral analysis and assessment of the surrounding environment, appropriate environmental adjustments should be made for each patient. The basics include displaying signs to the toilet, guiding the patient to defecate at the timing confirmed using their bowel diary, improving the environment by adjusting lighting, and reviewing the care for dementia[492,514]. In some cases, the patient may still feel a sense of shame about unhygienic behaviors (they may hide underwear soiled by feces). Thus, preventive care that respects the patient's self-esteem is required. If the patient attempts to remove the stool from the diaper on their own or play with the stool due to discomfort caused by fecal impaction, appropriate treatment of constipation can prevent these unhygienic behaviors[515]. In response to stool playing, the caregiver should remain calm and promptly dispose of the stool. In general, specialized treatment is not indicated for FI in patients with dementia[518].

In contrast, caregivers are placed under great mental and physical strain and may fall into a state of depression. Thus, a support system should be established so that caregivers do not feel isolated [515,517]. Giving caregivers time to relax and building a good relationship with patients will lead to a reduction in behavioral symptoms.

C. Frail or bedridden older adults

Abstract

Frail or bedridden older adults are prone to overflow fecal incontinence (FI) caused by fecal impaction. Thus, fecal impaction should be prevented by regular defecation induction and planned defecation using suppositories or enemas. For FI associated with constipation, the type and dosage of laxatives should be adjusted by considering the frequency of defecation and stool consistency.

Commentary

Although there are various definitions of frailty, the Car-

diovascular Health Study criteria[519] deem a person frail if he/she meets three or more of the following five items: weight loss, decreased activity, decreased muscle strength, decreased walking speed, and fatigue; pre-frail if meeting one or two items; and healthy if meeting none of the items. The prevalence of FI in nursing home residents is as high as approximately 50%, and although FI is recognized among nursing home residents, it is rarely acknowledged as a problem, and treatment and care are not always proactive[14,492]. However, even in frail or bedridden older adults, treatment is often possible with assessment and understanding of the pathophysiology[492].

Initial treatment is the same as conservative therapies for general FI, but the patient, their family, and caregivers should be interviewed regarding the patient's condition to select a feasible treatment method and to develop a treatment plan tailored to each individual patient[520]. A characteristic condition of frail or bedridden older adults is overflow FI due to fecal impaction[521]. The causes of fecal impaction are diverse, including long periods of time spent lying or sitting, decreased abdominal pressure during defecation, inadequate fluid and fiber intake, metabolic diseases such as hypothyroidism and hypokalemia, use of drugs that inhibit gastrointestinal motility, and neurological diseases such as cerebral infarction and Parkinson's disease[522]. Therefore, it is important to prevent fecal impaction by inducing regular defecation and planned defecation using sup�ories or enemas. In an RCT of patients with FI in a nursing home, FI was significantly improved by fecal characteristic adjustments and regular enemas[287]. In addition, in an RCT of frail patients, FI was significantly improved by inducing defecation and exercise 5 days a week[523]. Bedridden older adults often need to wear diapers, but if the patient is able to communicate the urge to defecate, having the patient defecate using a toilet in bed will reduce the burden on caregivers[524].

In contrast, excessive administration of laxatives for fear of fecal impaction can cause diarrhea and incontinence-associated dermatitis (IAD)[493]. In the case of FI associated with constipation, laxatives must be controlled by considering the frequency of defecation and stool consistency. In addition, diarrhea tends to occur in patients on enteral nutrition due to (1) administration of high-concentration enteral nutrition formulas, (2) administration rate being too fast, (3) temperature of nutrition formulas being too low, (4) bacterial proliferation, and (5) a lack of dietary fiber[525]. Anal insert device has been reported to be useful for bedridden older adults with diarrhea[526]. For more information on care and prevention of IAD, please refer to II-A-2-c and IV-A-3.

Conflicts of Interest

The cost of professional proofreading during the transla-

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Japanese Practice Guideline for Fecal Incontinence 2024

tion of this guideline into English was borne by the Japan Society of Coloproctology.

Disclaimer

Tatsuya Abe and Toshiki Mimura are the Associate Editors of Journal of the Anus, Rectum and Colon and on the journal's Editorial Board. They were not involved in the editorial evaluation or decision to accept this article for publication at all.

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