The way the body manages bowel control is very complex. Problems may arise due to IBD itself, or as a result of other factors that can cause bowel control problems for people whether or not they have IBD. The most common causes of bowel incontinence for people with IBD are:

• An ‘overactive’ bowel or loose stools. When IBD is active (and sometimes when it is not) you are likely to have diarrhea, or loose stools. Some people have bowels that are a lot more active than others, or are sensitive and easily upset.

• Increased sensitivity. Any part of the body that is inflamed is more sensitive and the bowel is no different. Inflammation in the rectum can increase the sense of urgency. As a result, the rectum becomes more active, pushing stools out as soon as they arrive. If stools are loose, or the activity in the bowel is causing the rectum to fill more often, this will be more difficult to control.

• Damage to the muscles. Muscle control is crucial to bowel control. The muscles of the anus can be damaged by childbirth, or by an anal fistula (abnormal channel connecting the back passage to the surface of the skin near the anus). The muscles can also be damaged by surgery for a fistula or to form a pouch.

• Damage to the nerves. Nerves control both the feelings (sensations) from the bowel, and the ability to do something about a full rectum, such as keeping the external muscle of the anus closed. Nerves can be damaged from birth, or later in life.

• Surgery for IBD. Pouch surgery (operation to create an internal pouch after removal of the colon), removal of a length of the bowel, or surgery for an anal fistula or abscess, can increase the likelihood of bowel incontinence for some people.

• Severe constipation. Some people with IBD experience constipation rather than diarrhea. If the lower bowel becomes overloaded with hard stools, this irritates the bowel lining which then produces more mucus. If the rectum is full continuously, the muscles of the anus relax which means that the liquid mucus may bypass the hard stool and leak out. This can be mistaken for diarrhea. Drinking enough fluid can help relieve constipation.

• Perianal fistulas. These connect the anal canal (back passage) to the surface of the skin near the anus. They can sometimes leak blood or mucus, but they might leak feces, which can lead to incontinence. 

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