Fecal incontinence has many causes, including digestive tract disorders and chronic diseases. Some causes of fecal incontinence, such as childbirth by vaginal delivery, happen only in women.
Diarrhea
Loose, watery stools from diarrhea fill your rectum quickly and are harder to hold in than solid stools. Diarrhea is the most common risk factor for fecal incontinence for people not staying in hospitals, nursing homes, or other similar institutions. Diarrhea may be caused by digestive tract problems such as
- inflammatory bowel disease
- irritable bowel syndrome
- proctitis
Constipation
Constipation can lead to large, hard stools that are difficult to pass. The hard stools stretch and, over time, weaken the muscles in your rectum. The weakened muscles let watery stools that build up behind the hard stool leak out.
Muscle injury or weakness
If the muscles in your anus, pelvic floor, or rectum are injured or weakened, they may not be able to keep your anus closed, letting stool leak out. These muscles can be injured or weakened by
- surgery to
- remove cancer in the anus or rectum
- remove hemorrhoids
- treat anal abscesses and fistulas
- trauma
Nerve damage
If the nerves that control your anus, pelvic floor, and rectum are damaged, the muscles can’t work the way they should. Damage to the nerves that tell you when there is stool in your rectum makes it hard to know when you need to look for a toilet. Nerves can be damaged by
- a long-term habit of straining to pass stool
- brain injury
- spinal cord injury
Neurologic diseases
Neurologic diseases that affect the nerves of the anus, pelvic floor, or rectum can cause fecal incontinence. These diseases include
- dementia
- multiple sclerosis
- Parkinson’s disease
- stroke
- type 2 diabetes
Loss of stretch in the rectum
If your rectum is scarred or inflamed, it becomes stiff and can’t stretch as much to hold stool. Your rectum can get full quickly, and stool can leak out. Rectal surgery, radiation therapy in the pelvic area, and inflammatory bowel disease can cause scarring and inflammation in your rectum.
Hemorrhoids
Hemorrhoids can keep the muscles around your anus from closing completely, which lets small amounts of stool or mucus to leak out.
Rectal prolapse
Rectal prolapse—a condition that causes your rectum to drop down through your anus—can also keep the muscles around your anus from closing completely, which lets small amounts of stool or mucus leak out.
Physical inactivity
If you are not physically active, especially if you spend many hours a day sitting or lying down, you may be holding a lot of stool in your rectum. Liquid stool can then leak around the more solid stool. Frail, older adults are most likely to develop constipation-related fecal incontinence for this reason.
Childbirth by vaginal delivery
Childbirth sometimes causes injuries to the anal sphincters, which can cause fecal incontinence. The chances are greater if
- your baby was large
- forceps were used to help deliver your baby
- you had a vacuum-assisted delivery
- the doctor made a cut, called an episiotomy, in your vaginal area to prevent the baby’s head from tearing your vagina during birth
Rectocele
Rectocele is a condition that causes your rectum to bulge out through your vagina. Rectocele can happen when the thin layer of muscles separating your rectum from your vagina becomes weak. Stool may stay in your rectum because the rectocele makes it harder to push stool out.