Fecal incontinence can occur briefly during bouts of diarrhea or when hard stool becomes lodged in the rectum (fecal impaction). Persistent fecal incontinence can develop in people who have injuries to the anus or spinal cord, rectal prolapse (protrusion of the rectal lining through the anus), dementia, neurologic injury resulting from diabetes, tumors of the anus, or injuries to the pelvis during childbirth.
A doctor examines the person for any structural or neurologic abnormality. This examination involves examining the anus and rectum, checking the extent of sensation around the anus, and usually doing a sigmoidoscopy.
Other tests, including an ultrasound of the anal sphincter, magnetic resonance imaging (MRI) of the pelvis and perineal area, an examination of the function of nerves and muscles lining the pelvis, and pressure readings of the rectum and anus (anorectal manometry) may be needed.
The first step in correcting fecal incontinence is to try to establish a regular pattern of bowel movements that produces well-formed stool. Dietary changes, including the addition of a small amount of fiber, often help. If such changes do not help, a drug that slows bowel movements, such as loperamide, may be successful.
Exercising the anal muscles (sphincters) by squeezing and releasing them increases their tone and strength. Using a technique called biofeedback, a person can retrain the sphincters and increase the sensitivity of the rectum to the presence of stool. About 70% of well-motivated people benefit from biofeedback.
If fecal incontinence persists, surgery may help—for instance, when the cause is an injury to the anus or an anatomic defect in the anus. As a last resort, a colostomy (the surgical creation of an opening between the large intestine and the abdominal wall—see Figure: Understanding Colostomy) may be done. The anus is sewn shut, and stool is diverted into a removable plastic bag attached to the opening in the abdominal wall.