Diarrhea
The urgency and rapid speed of bowel movements can overwhelm the ability of the sphincter muscles in the rectum to hold stool in place. People who suffer conditions that cause chronic diarrhea, such as irritable bowel syndrome (IBS) or inflammatory bowel disease, may experience episodes of incontinence. Inflammatory bowel disease also can cause rectal scarring, which may lead to incontinence.Constipation
Although it seems to fly in the face of logic, it is possible to experience soiling when constipated. This happens when watery stool leaks its way around the hard, compacted stool mass. A long history of straining to produce stool (often an end product of chronic constipation), can damage the nerves in the muscles of the rectum, causing weakness and an inability to contain stool.Childbirth
For women, childbirth is the leading cause of incontinence. It's most likely to occur following a complicated delivery, particularly when forceps are used or an episiotomy is performed. An episiotomy is a procedure in which the doctor cuts the vaginal area to prevent the area from being torn. The risk here is that the sphincter muscles -- the muscles at the bottom of the rectum that have the job of containing stool -- are damaged in the process. This may prevent them from adequately holding stool, resulting in incontinence. Vaginal childbirth also raises a woman’s risk of experiencing pelvic floor dysfunction.Pelvic Floor Dysfunction
The term "pelvic floor" refers to a group of muscles in the pelvic region that are involved in the process of having a bowel movement. Dysfunction and nerve damage in the pelvic floor muscles can be the result of pregnancy, vaginal childbirth and pelvic surgery. Pelvic floor dysfunction causes a general weakness and sagging in the pelvic muscles, a diminished ability of the nerves of the rectum to sense the presence of stool, and an impairment in the movement of the muscles involved in the process of defecation -- all of which can lead to incontinence.Rectal Surgery
Any type of rectal surgery, whether it be for cancer or hemorrhoids, raises your risk for experiencing incontinence. In fact, anal surgery is the leading cause of incontinence in men. Surgery, like childbirth, can result in muscle and nerve damage that then interferes with the normal process of defecation. Surgery also presents the risk of scarring of the rectal walls, causing them to lose elasticity. The resulting inability of the rectum to stretch can result in difficulty containing stool and therefore incontinence occurs.Cancer Radiation Treatment
Similar to rectal surgery, radiation treatment can result in damage and scarring of the rectal walls leading to incontinence.Neurological Conditions
Diseases and conditions that damage nerve tissue can also cause incontinence, particularly if they affect the nerves that control defecation. These conditions include multiple sclerosis, stroke, spinal cord injuries and diabetes.
Sources:
Landefeld, C. et.al. National Institutes of Health State-of-the-Science Conference Statement: Prevention of Fecal and Urinary Incontinence in Adults Annals of Internal Medicine 2008 148:449-458.
International Foundation for Functional Gastrointestinal Disorders “Reporters Guide to Bowel Incontinence”.
National Digestive Diseases Information Clearinghouse (NDDIC) “Fecal Incontinence”.
Lunniss, P. et.al. “ Risk factors in acquired faecal incontinence” Journal of the Royal Society of Medicine 2004 97:111-116.
