Continence requires the normal function of and the nervous system. The anal sphincters, along with the pelvic muscles that surround the end of the digestive tract, ensure controlled movement of digestive tract contents. There are many possible causes of fecal incontinence; in most cases, incontinence results from some combination of these causes.
Critical to normal bowel function are:
- Anal sphincter muscles – Anal muscles contract to prevent stool from leaving your rectum
- Rectal sensation – This feeling warns you to go to the toilet
- Rectal accommodation – Rectal stretching allows you to hold stool until you can get to a toilet
A broad range of conditions and disorders can cause fecal incontinence, including: Damage of the anal sphincters — The internal and external anal sphincters are the muscles located at the end of the rectum (see diagram). These muscles and the surrounding pelvic muscles create a barrier that prevents the escape of feces. Any damage to or loss of control over these sphincters can lead to incontinence. Damage may occur from any of the following:
- Trauma during vaginal childbirth, forceps delivery or episiotomies
- Damage following anal surgery such as hemorrhoid or fissure surgery
Neurologic causes — Neurologic disorders such as diabetes, multiple sclerosis, and spinal cord injury can decrease sensation and neural control over the lower digestive tract. Nerve damage during vaginal childbirth can also lead to impaired anal sphincter function.
Decreased distensibility of the rectum — Conditions such as inflammatory bowel disease (ulcerative colitis and Crohn’s disease) and radiation-induced inflammation of the rectum can impair this structure’s ability to expand and store fecal matter.
Constipation and Fecal impaction — Collection of hardened feces in the rectum can cause the anal sphincters to relax and allow liquid stool to escape around the blockage. Fecal impaction is a common cause of incontinence in older adults. Factors that make impaction more likely include certain mental health conditions, immobility and poor intake of liquids and fiber.
Other conditions and causes:
- Chronic laxative abuse – Relying on laxatives to maintain regularity can lead to incontinence
- Diarrhea – Solid stool is easier to retain in the rectum than is loose stool, so the loose stools of diarrhea can cause or worsen fecal incontinence
- Hemorrhoids – may prevent complete closure of the anal sphincter, leading to fecal incontinence
- Rectal cancer – cancers of the anus and rectum can lead to fecal incontinence if the cancer invades the muscle walls or disrupts the nerve impulses needed for defecation
- Rectal Prolapse – A condition in which your rectum drops down into your anus
- Rectocele – A condition in women in which the rectum protrudes through the vagina
- Loss of muscle strength with age – Over time, muscles and ligaments that support your pelvis, as well as your anal sphincter muscles, can weaken, leading to incontinence
- Unknown causes — Sometimes the cause of fecal incontinence cannot be identified. In this case, the condition is called idiopathic incontinence. Idiopathic incontinence most commonly occurs in middle-aged or older women
The lower end of the digestive tract is called the rectum and anus. It is here that one controls the waste products (feces) of the digestive system. The internal and external anal sphincters enable one to sense a bowel movement and they act as final valves to hold stool until one is ready to evacuate.
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For more information on causes of fecal incontinence, or to schedule a consultation, please contact Colorectal Surgical Associates today.