Anorectal

Fecal Incontinence

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Fecal incontinence is associated with great physical and social disability. However, the condition is often underrecognised by health care professionals, since defecation and especially impaired continence remains a taboo subject that is difficult to discuss and often not declared by the patient. Therefore, it has been suggested to prefer the term „accidental bowel leakage“ instead. The prevalence for accidental bowel leakage is high, especially in the older (female) population (age 70 years and above) up to 16% are affected.

The main determinants of fecal continence include 1) stool consistency, by far, the single biggest risk factor for involuntary loss of stool (liquid stools are more difficult to maintain) 2) rectal capacity (a larger rectal reservoir volume can retain more) 3) anorectal sphincter function, and 4) anorectal perception.

Therefore, the initial management of fecal incontinence demands regulation of bowel habit and stool consistency, i.e. by the use of bulking agents or loperamide. In patients who fail to respond to empiric management, diagnostic testing includes endoscopy (to rule out fecal impaction or paradoxic diarrhea, e.g due to malignant strictures), ideally with (endoscopic) ultrasound and magnetic resonance imaging to exclude rectal inflammation, neoplasia, anal sphincter defects or trauma to the pelvic floor. However, in the absence of overt ‘organic disease’ these investigations provide little insight into the cause of symptoms and no guide to therapy. In this situation, the comprehensive assessment of anorectal function is indicated. Anorectal manometry (ARM) or high-resolution ARM acquires sphincter function by measurements of sphincter resting tone, voluntary squeeze pressure and rectoanal coordination during simulated defecation. This is often followed by measurements of rectal capacity, compliance and rectal sensitivity by determining the perception threshold for initial sensation, urge and maximum tolerated volume during defined distensions of a rectal balloon. Recently, standardized operating procedures (SOPs) for those measurements have been published.

Current therapy of fecal incontinence remains difficult and patient selection is key to the success of management. Comprehensive measurements of anorectal function help to tailor the optimal medical, behavioral (biofeedback) or surgical (e.g. sacral nerve modulation, sphincter reconstruction) therapy to an individual patient.


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Functional Defecation Disorders

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In a significant subset of patients suffering from chronic constipation or constipation-predominant IBS slow colonic transit is not or at least not the only underlying cause of impaired evacuation. Structural anorectal abnormalities such as rectocele with intussuception may lead to an outlet obstruction, which can easily be detected by imaging (e.g. MRI defecography), whereas initial investigation of anorectal mucosa and anatomy by endoscopy (to rule out rectal cancer or colonic neoplasia) rarely provides a definitive diagnosis. In patients with obstructive defecation the underlying cause of these symptoms is often abnormal anorectal function, related to inadequate propulsion forces or dyssynergic defecation. Patient presentation usually does not distinguish between functional, structural, or behavioral pathology. A digital rectal examination can provide a useful clinical assessment in the hands of a skilled clinician. In patients who do not respond to empiric toileting advice and laxative treatment, anorectal function testing by (high-resolution) anorectal manometry and imaging is indicated to identify the cause of symptoms and to tailor treatment. The introduction of high-resolution anorectal manometry systems that acquire measurements from at least 10 closely spaced pressure sensors across the anal sphincter removes the need for a pull-through procedure and provides visual feedback to the operator that facilitates maintenance of a stable catheter position and to avoid movement artifacts. Assessment of abnormal anorectal function and behavior, demonstrating inadequate propulsive forces or inappropriate contraction of the anal sphincter and/or pelvic floor muscles during attempted defecation (dyssynergia) is clinically relevant because patients with dyssynergic defecation respond to biofeedback and training to improve toileting behavior, whereas patients with structural pathologies require other management.


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