Approach
Faecal incontinence is a symptom, and the cause is often multifactorial. A structured approach to management is required, beginning with diagnosis and correction of reversible contributing factors. A baseline assessment should include history, examination, and anoscopy/sigmoidoscopy. A cognitive assessment may also be appropriate if learning difficulties, dementia, or behavioural issues are suspected to be a contributing factor. Specialised tests are done subsequently only if initial conservative management fails to improve symptoms. It is essential to consider and exclude the possibility of colorectal cancer in anyone presenting with incontinence.
History
Identification of possible risk factors (e.g., a history of inflammatory bowel disease, bowel resection, rectal prolapse, or constipation) and characterisation of duration and severity of symptoms are important.[26] Neurological disorders such as multiple sclerosis or previous spinal injury may be present. Any potential warning signs for a lower gastrointestinal malignancy should be sought (e.g., weight loss, blood in the stool, previous polyps, or a family history of bowel cancer). A detailed obstetric history focusing on vaginal deliveries, episiotomy, perineal tearing, the use of forceps, delayed second stage, and the size of the baby are essential. The American College of Obstetricians and Gynecologists (ACOG) recommends a complete medical history, assessment of symptoms, and physical examination of the rectal, vaginal, and perineal areas in women with symptoms of faecal incontinence.[27] Preceding constipation may suggest overflow diarrhoea and a recent travel history may be compatible with an infectious aetiology.
Symptoms may include passive leakage or seepage, and faecal incontinence is often found in conjunction with urinary incontinence, as similar mechanisms underlie both. Urgency is usually associated with reduced rectal capacity or rapid arrival of liquid stool in the rectum, as found with infectious causes.
It is important to obtain an assessment of the severity of the incontinence, taking into account factors such as type, frequency, and amount of incontinence and impact on all aspects of quality of life. This also allows monitoring of response to therapy. Numerous incontinence scales exist to assess severity but many lack reliability and validity. Acceptable reliability appears to be demonstrated in the Vaizey, Jorge/Wexner, and American medical system scales.[28][29]
Wexner score: considers three types of incontinence (solid, liquid, and gas), the need to wear a pad, and lifestyle alteration. Frequency of each factor is given a score of 0 (never), 1 (rarely), 2 (sometimes), 3 (usually), or 4 (always).
Vaizey score: similar to the Wexner score but designed to include urgency and the need to use constipating medications. Incontinence to solid stool, liquid stool, and gas, and lifestyle alteration are assessed. The frequency of each of these factors is given a score of 0 (never), 1 (rarely), 2 (sometimes), 3 (weekly), or 4 (daily). Additionally, patients are asked about the need to wear a pad or plug, the use of constipating medications, and the lack of ability to defer defecation for 15 minutes. A positive response scores 2 points each for the use of pads or constipating medication and 4 points for urgency.
American medical system score: patients are asked to recall symptoms over the preceding 4 weeks. Symptoms are classified by six frequencies: never, rarely, sometimes, weekly, daily, or several times daily. Scores are given based on five questions:
Did you experience accidental bowel leakage of gas?
Did you experience minor bowel soiling or seepage?
Did you experience significant accidental bowel leakage of liquid stool?
Did you experience significant accidental bowel leakage of solid stool?
Has this accidental leakage affected your lifestyle?
Examination
Inspection of the perineum may show scarring or fistulae. Straining down, particularly if on a commode, will identify rectal prolapse. Digital examination is helpful to assess both resting and squeeze tone (including maintenance of squeeze pressure) and will identify faecal impaction. A rectal mass may be due to impaction from a faecal bolus or a rectal malignancy. A patulous anus is a sign of low resting sphincter pressure. Reduced perianal sensation with a relevant history may indicate acute disc prolapse or cauda equina syndrome. Anoscopy/sigmoidoscopy will identify haemorrhoids or inflammatory bowel disease and may reveal a mass.
Investigations
Subsequent tests are appropriate if symptoms do not improve with conservative management and specific causes such as cauda equina or haemorrhoids have been addressed. The choice of test depends on the suspected underlying aetiology and these usually take place at specialised centres. If an anal sphincter problem is suspected, anal manometry and endoanal ultrasound are recommended.[26][30]
If available, electromyography and pudendal nerve testing can also be done, although not all centres offer these tests routinely. Proctography is reserved for patients with suspected prolapse. Stool cultures, blood tests (full blood count, C-reactive protein), and rectal biopsy are necessary only if the history suggests incontinence is due to diarrhoea; otherwise they are not routinely requested.
Anal manometry gives an objective assessment of anal continence. It allows measurement of anal pressure generated at rest and during squeeze, giving an idea of internal and external sphincter function, respectively. It also identifies the presence of normal reflexes associated with defecation, particularly the recto-anal inhibitory reflex, and measurement of sensation of the rectum. These factors may be abnormal with neurological disorders. Increased rectal sensitivity may be seen in irritable bowel syndrome. Rectal capacity and compliance may be altered in diseases that reduce the reservoir function of the rectum (e.g., after bowel resection). Anorectal physiology tests have been shown to be both reliable and reproducible.[31]
Endoanal ultrasound: identifies sphincter defects with almost 100% accuracy when performed by an experienced clinician.[32] This, along with physiology testing, forms part of the assessment of patients whose incontinence has not responded to initial management. Developments in technology including 3D imaging have improved accuracy and understanding of sphincter pathology, and have allowed for calculation of sphincter volumes.[33][34] Transvaginal and transperineal ultrasound are ongoing developments in this field. They may allow more detailed assessment, particularly if other pelvic floor compartment pathology exists.[33]
Endoanal magnetic resonance imaging: has been advocated by some authors to delineate the anal sphincter complex as an alternative to endoanal ultrasound. The external sphincter is seen clearly and defects are easily identified. The clarity of the external sphincter does not mean that this is a superior test to endoanal ultrasound, but does allow a more accurate diagnosis of atrophy, which may be a predictor of the success of sphincter repair.[35][36][37]
Pudendal nerve terminal motor latency testing: a measurement of the length of time required for a fixed electrical stimulus to travel along the pudendal nerve. Increased latency is an indication of pudendal neuropathy and may be associated with poor outcome after sphincter repair.[38][39][40] Due to operator/laboratory variability and overlap of normal and abnormal values, this test has limited clinical value. This test is not recommended routinely.[26]
Proctography: may be useful in selected patients with a clinical suspicion of prolapse or intussusception.
Endoscopic evaluation is recommended to rule out other pathology in patients with faecal incontinence having symptoms such as diarrhoea, bleeding, urgency, tenesmus, and mucus drainage.[26]
ACOG recommends colonoscopy in women with faecal incontinence with changes in bowel habits accompanied by unexplained weight loss, abdominal pain, rectal bleeding, melena, or anaemia.[27]
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