Fecal incontinence

Fecal incontinence is a distressing and stigmatizing condition affecting at least 2% of the adult population and 7% of healthy, independent adults aged >65 years; however, the true community prevalence is underestimated ^(21,22). Incontinence may have several causes; anal sphincter injury is highly prevalent, particularly among women, and is potentially treatable.

The maintenance of normal fecal continence requires the proper interplay and function of colonic transit time and absorption, the puborectalis and anal sphincter muscles, local motor and sensory nerves, and central nervous system function in the spinal cord and cerebral cortex. A deficit in any of these systems can result in fecal incontinence.

In patients without colonic disease (diarrhea, overflow incontinence), the causes include anal sphincter injuries (which may be occult), peripheral neuropathy, and functional incontinence ⁽²¹⁾.

Anal sphincter injuries occur as a consequence of prior anorectal surgery, obstetrical trauma, or accidental injuries. Injuries may remain occult for long periods, particularly in obstetrical trauma.

Compensation by contraction of the puborectalis muscle, which makes the rectal angle more acute, may allow for maintenance of fecal continence in some patients with anal sphincter injury. In female patients, when pelvic descent occurs with aging (often associated with rectocele or cystocele), there is straightening of the rectal angle, placing the puborectalis at a mechanical disadvantage, which results in fecal incontinence ^(21,22).

Rectal endoscopic ultrasonography (EUS), along with anorectal manometry and electromyography, is often useful in evaluating incontinence (Figure 4A). Anal sphincter injuries appear as hypoechoic defects in the respective sphincter rings and are usually located anteriorly (Figure 4B). The detection of sphincter defects via EUS correlates well with findings at surgery; this diagnostic method has a sensitivity of 95% to 100% and a specificity of 75% to 100% ^(21,22).

Surgical repair of the injured sphincter is often undertaken using the technique of overlapping anterior sphincteroplasty. Following surgery, satisfactory continence of solid and liquid stool is achieved in 70% to 80% of patients ⁽²¹⁾.

Deepak V. Gopal, MD, FRCP (C)

Assistant Professor of Medicine
Division of Gastroenterology
Oregon Health & Science University
Portland VA Medical Center
Portland, Oregon

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