Causes of fecal incontinence include diarrhea, constipation, nerve damage, muscle damage and surgery, according to Mayo Clinic. Rectal prolapse, a condition in which the rectum moves into the anus, and rectocele may also cause bowel incontinence.
Damage to nerves due to constipation, spinal cord injury, stroke and childbirth may hinder sensation of stool and control of the anal sphincter, leading to fecal incontinence, notes Mayo Clinic. Diseases such as multiple sclerosis and diabetes can also injure the nerves. Severe constipation may cause a mass of dry stool to form in the rectum, stretching and weakening rectal muscles. A weak rectum is unable to control bowel movements.
Fecal incontinence may occur due to surgery and other operations done to reverse problems in the rectum or anus, according to Mayo Clinic. The operations may damage nerves or muscles in the anus or rectum. Surgery, inflammatory bowel disease and radiation treatment can damage or harden muscles of the rectum, resulting in leakage.
Injury to anal muscles, a common problem associated with the use of forceps or episiotomy, may cause loss of bowel control, explains Mayo Clinic. Diarrhea makes it difficult for the rectum to hold bowels. Risk factors for fecal incontinence include physical disability, dementia and late-stage Alzheimer's disease. Bowel incontinence is more common in women older than 45.