Anal Incontinence

Anal Incontinence

Anal incontinence is the inability to control your bowels. When you feel the urge to have a bowel movement, you may not be able to hold it until you get to a toilet. Stool may also leak from the rectum unexpectedly, sometimes while passing gas.


More than 5.5 million Americans have anal incontinence. It affects people of all ages – children and adults. Anal incontinence is more common in women and older adults, but it is not a normal part of aging. Loss of bowel control can be devastating. People who have anal incontinence may feel ashamed, embarrassed or humiliated. Some don’t want to leave the house out of fear that they might have an accident in public. Most try to hide the problem as long as possible, so they withdraw from friends and family. The social isolation is unfortunate, but may be reduced with treatment that improves bowel control and makes incontinence easier to manage.

What causes anal incontinence?

Anal incontinence can have several causes:

  • Constipation
  • Damage to the anal sphincter muscles
  • Damage to the nerves of the anal sphincter muscles or the rectum
  • Loss of storage capacity in the rectum
  • Diarrhea
  • Pelvic Floor Dysfunction



Constipation is one of the most common causes of anal incontinence. Constipation causes large, hard stools to become lodged in the rectum. Watery stool can then leak out around the hardened stool. Constipation also causes the muscles of the rectum to stretch, which weakens the muscles so they can’t hold stool in the rectum long enough for a person to reach a bathroom.

Muscle Damage

Anal incontinence can be caused by injury to one or both of the ring-like muscles at the end of the rectum called the anal internal and external sphincters. The sphincters keep stool inside. When damaged, the muscles aren’t strong enough to do their job and stool can leak out. In women, the damage often happens when giving birth. The risk of injury is greatest if the doctor uses forceps to help deliver the baby or performs an episiotomy, which is a cut in the vaginal area to prevent it from tearing during birth. Hemorrhoid surgery can also damage the sphincters.

Nerve Damage

Anal incontinence can be caused by damage to the nerves that control the anal sphincters or the nerves that sense stool in the rectum. If the nerves that control the sphincters are injured, the muscles don’t work properly and incontinence can occur. If the sensory nerves are damaged, they don’t sense that stool is in the rectum so you won’t feel the need to use the bathroom until stool has leaked out. Nerve damage can be caused by childbirth, a long-term habit of straining to pass stool, stroke, physical disability due to injury and diseases that affect the nerves such as diabetes and multiple sclerosis.

Loss of Storage Capacity

Normally, the rectum stretches to hold stool until you can get to a bathroom. But rectal surgery, radiation treatment and inflammatory bowel disease can cause scarring that makes the walls of the rectum stiff and less elastic. The rectum then can’t stretch as much to hold stool and anal incontinence results. Inflammatory bowel disease also can irritate rectal walls, making them unable to contain stool.


Diarrhea, or loose stool, is more difficult to control than solid stool because with diarrhea, the rectum fills with stool at a faster rate. Even people who don’t have anal incontinence can leak stool when they have diarrhea.

Pelvic Floor Dysfunction

Abnormalities of the pelvic floor muscles and nerves can cause anal incontinence. Examples include:

  • Impaired ability to sense stool in the rectum
  • Decreased ability to contract muscles in the anal canal to defecate
  • Dropping down of the rectum, a condition called rectal prolapse
  • Protrusion of the rectum through the vagina, a condition called rectocele
  • General weakness and sagging of the pelvic floor
  • Childbirth is often the cause of pelvic floor dysfunction, and incontinence usually doesn’t appear until the mid-forties or later.