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Anal incontinence is defined as the involuntary loss of feces or flatus. It is a socially isolating, physically and psychologically disabling condition that often has profound consequences on all aspects of quality of life. The prevalence of fecal incontinence (FI) in the community-based adult UK population is between 2% and 3%,1 rising with age to approximately 6% to 7% in the elderly people in the community, and 10% of patients in elderly care homes.2,3 Because anal incontinence is a source of embarrassment, many patients do not volunteer these symptoms or seek medical advice, hence, it is thought that the condition is even more common than these figures suggest. Epidemiologic data suggest that men and women are equally affected,2,4,5 which is surprising given that most research is focused on anal incontinence in the female population. Simple, low-cost interventions can often improve symptoms in a large number of patients. For refractory patients, more sophisticated second-line investigations and treatments have become available in recent years. This chapter will review the etiology, pathophysiology, and management of anal incontinence, with particular attention focused on the evolving areas of our increased understanding in terms of investigation and management.
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FI is rarely attributable to a single factor but usually results from the interplay of multiple pathogenic mechanisms (Table 9-1). Obstetric anal sphincter trauma is the most well-recognized risk factor, and sphincter defects are associated with both abnormal physiology and symptoms of FI.6 Due to the stigma of incontinence, it remains grossly underreported with many women suffering in silence,7 and many women often present years after the initial obstetric injury. Other risk factors include the effect of aging, declining estrogen support of the pelvic floor connective tissue after menopause, or progression of neuropathy and anal sphincter atrophy.6
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Most patients with sphincter defects alone do not develop incontinence,6,8 and equally, abnormal anal canal manometry correlates poorly with symptoms.9,10 The rectum plays an important role in the continence mechanism—this is most clearly demonstrated by poor functional outcome after surgical rectal excision where symptoms of incontinence correlate with the length of ...