What Can Go Wrong - Fecal Incontinence: Bladder Conditions

Content provided by the Faculty of the Harvard Medical School

What can go wrong?

Fecal incontinence is a symptom, not a disease, and it can result if something goes wrong with any of the coordinated mechanisms that help maintain continence. The problem is not always caused by a malfunction in the gastrointestinal tract. In some situations, functional incontinence occurs when an unrelated condition, such as arthritis, makes it physically difficult to reach the toilet when you have the urge. Dementia may also result in incontinence. But incontinence that involves the malfunction of the bowel or rectum has several common causes.

Bowel problems. Even if your rectum and anal canal are functioning properly, the system can be overwhelmed by conditions that speed the passage of waste products through the colon, resulting in diarrhea. You may have incontinence temporarily if you develop diarrhea during a bout of food poisoning or in reaction to a medication.

Conditions that cause chronic diarrhea, such as irritable bowel syndrome and inflammatory bowel disease, can result in occasional or ongoing problems with fecal incontinence. Diabetes can cause nighttime diarrhea that is difficult to control. Sometimes people with a little sphincter damage are able to maintain continence as long as their bowel movements are normal and predictable. But years after the damage, a bowel problem may develop that ends their control.

Reduced rectal capacity. Surgery, pelvic radiation (to treat cancer of the prostate or uterus), or inflammatory bowel disease can stiffen or scar the rectum. The rectum will not be capable of storing a normal amount of stool if its walls lose elasticity — and diarrhea may be particularly difficult to hold. You will have less time between the sensation of stool being present and an urgent need to use the bathroom.

Constipation. If hard fecal matter becomes stuck in the rectum, a situation called impaction, liquid stool will eventually leak out around it. This type of fecal incontinence is called overflow incontinence. It can be confused with diarrhea, but antidiarrheal medications will only make the situation worse.

Sphincter damage. If the internal anal sphincter is damaged, bits of stool can leak out without you being aware of it or able to control it. This may occur at times of physical exertion or after you have had a bowel movement. If your internal sphincter is damaged, you may find it difficult to completely clean yourself after a bowel movement — every time you wipe, more stool appears.

If, on the other hand, the external anal sphincter muscles are damaged, you are more likely to feel urgency — you must rush to the bathroom as soon as you feel stool in the rectum. You may be unable to squeeze hard enough or long enough to make it to the toilet, and incontinence occurs.

In women, the most common cause of sphincter injury is vaginal childbirth. The risk is increased for large babies, older mothers, a long second stage of labor, forceps deliveries, tears that extend to the anus, and the use of episiotomy (an incision to extend the vaginal opening in an attempt to avoid a tear). Fecal incontinence may be apparent immediately after childbirth. When less severe sphincter damage occurs, however, symptoms of incontinence may not appear until decades later, when bowel habits become less predictable or the muscles weaken further.

The anal sphincters can also be damaged during rectal surgery (to treat prolapse, hemorrhoids, malformations, or rectal cancer), traumatic injury, or forceful anal intercourse.

Pelvic floor problems. If your pelvic floor muscles become weak, or contract and relax at inappropriate times, fecal incontinence can result. Pelvic floor weakness may result from vaginal deliveries or years of straining to defecate. When the muscles supporting the rectum are weak, the rectal lining can prolapse, shifting downward into the anal canal or even protruding from the body. If you have a rectal prolapse, you may feel an urgent need to go even when little stool is present. Your external sphincter must work harder to keep you continent, and the prolapse itself can cause sphincter damage. Most people with rectal prolapse have some degree of fecal incontinence.

Nerve damage. If nerves controlling the sphincters malfunction, proper muscle action is impaired, and incontinence may occur. If sensory nerves are damaged, it becomes difficult to perceive that there is stool in the rectum. The pudendal nerve is the major nerve supplying the external sphincter. Nerve damage resulting in incontinence can occur when the pelvic floor muscles are stretched or traumatized by childbirth or repeated straining to defecate, or if a person develops a neurological condition (such as multiple sclerosis, stroke, diabetic neuropathy, or spinal cord injury).

Rectocele. In women, the rectum may bulge into the vagina because of a weakening of the vaginal wall often caused by childbirth. Difficulties passing stool may result. A doctor can see and feel a rectocele close to the vaginal opening. A rectocele can make it difficult to empty your bowel completely. Some women find it helps to place two fingers inside the vagina to help support the bulging tissue and facilitate a bowel movement.

Last updated:	September 05, 2008