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Bowel Incontinence

What is fecal incontinence?
Bowel incontinence is the decreased ability to control gas or stool.  The symptoms range from mild expulsion of gas to a serious loss of control.  It is a common problem affecting 1 out of 13 women under the age of 60 and 1 out of 7 women over the age of 60.  Men are also afflicted with this condition.  Bowel incontinence is a distressing condition that can interfere with the ability to work, enjoy social activities, and is a frequent reason for placement in a nursing home.  Despite bowel incontinence being a common condition, people are uncomfortable discussing this problem with family, friends, or doctors.  They often suffer in silence, not knowing that help is available.

How does it occur?
The anal sphincters and puborectalis are the primary muscles responsible for continence.  There are two sphincters: the internal anal sphincter, and the external anal sphincter.  The internal sphincter is responsible for 80% of the resting muscle tone, however it is involuntary.  This means, that you do not have control over this muscle.  Conversely, the external sphincter is responsible for 15-20% of your muscle tone.  You do have control over this muscle.  The remaining 5% of your continence depends on hemorrhoids, which may swell to prevent accidental leaking, and are also present in the area where sensation takes place. The puborectalis and external anal sphincter work together to close the anal canal at times of increased pressure. By squeezing these muscles voluntarily when you cough or sneeze you can prevent leakage.

Injury to the sphincter muscles may occur during childbirth.  A large baby, prolonged labor, forceps delivery, tears/lacerations, episiotomies or infection can cause a small injury.  These injuries may go unnoticed for years.  As the body ages, the injury may become apparent.

The rectum may also be responsible for incontinence.  The rectum, located above the sphincter muscles, stores stool until it is time to defecate (move your bowels).  Scarring from diseases such as Ulcerative colitis and Crohns disease or surgical removal of the rectum causes the rectum to lose the ability to hold stool.  Stool has no where to be stored and leaks out.

The most common cause of incontinence is frequent bowel movements and weak sphincters.  The rectum is full of hard, packed stool.  Only liquid stool can escape.  This can be a serious problem. 

Finally, rectoceles and rectal prolapses can cause leaking of stool.  Stool can get trapped by a rectocele.  When the rectocele returns to its original shape, stool can leak out.  If the rectum protrudes out, stool can likely follow.

The nerves that supply the sphincters are called the pudendal nerves.  They originate from branches of the spinal cord.  Stretching during a delivery, old age, trauma, or medical diseases that affect the nerves, such as diabetes, can injure them.  Without intact nerves to stimulate the sphincters, the sphincters will not function.  Loss of nerve function can also impair the ability to sense the need to defecate or distinguish between gas and stool. It may be impossible to know when stool comes out or when stool needs to come out.

Treatment for bowel incontinence varies depending on the source of the problem.  Some bowel incontinence may be treated with simple dietary changes, changes in current medications, and/or the use of medications that solidify stool.  In other cases, exercises to strengthen muscles or therapy to help patients sense when stool is ready to be evacuated can help.  Treatment of diseases that cause inflammation in the rectum may eliminate or improve symptoms of incontinence.  Injury to anal muscles and rectoceles may be repaired with surgery.

Information provided by the Michigan Bowel Control Program, March 2009