Why Incontinence Occurs
Continence depends on properly functioning muscles and nerves in and around the rectum and anal canal. Any condition that interferes with these complex mechanisms may result in incontinence.
Examples of events or conditions that can affect continence and lead to bowel incontinence or accidental bowel leakage (ABL) include:
- irritable bowel syndrome (IBS),
- inflammatory bowel disease (IBD),
- pelvic or anal surgery,
- neurological disorders or injuries, and
- radiation treatments for certain cancers.
- Muscle damage or weakness
Incontinence can be caused by injury to the ring-like sphincter muscles at the end of the rectum. The sphincter muscles normally stay tightly closed and keep stool in the rectum. If weakened by injury or disease, stool can leak out. In women, for example, the damage may happen as a result of complicated childbirth. Hemorrhoid surgery and other anal surgeries can also damage the sphincter muscles.
Nerve damage can impair sensation and muscle control. An individual with nerve damage may not feel the need to use the bathroom and stool may leak out unexpectedly. Nerve damage can be caused by complicated childbirth, long-term straining to pass stool, spinal cord injury, stroke, and neurological diseases such as diabetes, multiple sclerosis (MS), and Parkinson’s disease.
Bowel control can be overwhelmed by a sudden or urgent need to pass loose stool, especially if muscle or nerve function is also impaired. This can be a devastating symptom for individuals with chronic gastrointestinal conditions that cause diarrhea, such as irritable bowel syndrome (IBS) or after gallbladder surgery.
Long-term constipation can lead to the formation of a hard mass of stool in the colon. Liquid stool can seep around the mass and be difficult to control. This is the most common cause of fecal incontinence in children. In some cases the presence of liquid stool may lead to misdiagnosis and treatment for diarrhea, which only worsens the underlying problem.
Pelvic floor dysfunction
The pelvic floor is a group of muscles that not only supports the pelvic organs within the pelvis and lower abdomen but also plays an important role in defecation and maintaining continence. If pelvic floor function is disturbed, normal bowel control may be disrupted. An inability to adequately relax the pelvic floor muscles during defecation may lead to incomplete evacuation, which may also predispose to fecal incontinence. Pelvic surgery, pregnancy, or vaginal childbirth can contribute to development of a pelvic floor disorder.
Loss of storage capacity
Rectal surgery, radiation treatments for pelvic or colon cancers, and inflammatory bowel disease (IBD) can cause inflammation as well as scarring that stiffens the normally elastic walls of the rectum and lead to urgency and fecal incontinence. Some women have a reduced storage capacity without these conditions.
For more information:
Visit the Learning Center for topics on bowel incontinence or urgency.