DEAR DOCTOR K:
I’m in my late 50s, but I have fecal incontinence. What could be causing it?
We begin having bowel movements soon after birth, and controlling the process soon thereafter. So it is a surprising and disturbing event when we cannot hold our stool long enough to reach the bathroom, or experience unexpected leakage of stool when we haven’t felt any urge.
You should know that there are many people with this problem. Nearly 1 in 10 adults in the United States have episodes of fecal incontinence. All ages are affected — your case is not unusual — but fecal incontinence becomes more common as we get older.
When everything is working properly, muscles in the colon propel feces into the rectum, which sits at the end of your digestive tract. The rectum has walls that stretch to hold the stool. The last 1-1.5 inches of the rectum is called the anal canal. Two kinds of muscle surround it.
The internal anal sphincter, which is not under your conscious control, stays contracted most of the time to prevent leakage. The external anal sphincter, which you do control, surrounds the internal anal sphincter. (I’ve put an illustration on my website, AskDoctorK.com.)
Nerves tell your brain when your rectum is full. At this point you can decide to have a bowel movement or wait for a better time or place. If you choose to delay, you tighten the external anal sphincter to hold feces inside. You also contract a pelvic floor muscle that loops around the rectum.
Fecal incontinence can result if something goes wrong with any of these mechanisms:
- REDUCED RECTAL CAPACITY. Surgery, radiation or inflammatory bowel disease can stiffen or scar the rectum. The rectum loses elasticity and cannot store a normal amount of stool.
- CONSTIPATION. When hard stool becomes stuck in the rectum, liquid stool may leak out around it.
- SPHINCTER DAMAGE. If the internal anal sphincter is damaged, bits of stool can leak out without your knowledge or control. If the external anal sphincter muscles are damaged, you may be unable to squeeze them hard enough or long enough to make it to the toilet.
- PELVIC FLOOR MUSCLE WEAKNESS. Fecal incontinence can result if these muscles become weak, or if they contract and relax at inappropriate times.
- RECTAL PROLAPSE. When the muscles supporting the rectum are weak, the rectal lining may descend into the anal canal or protrude from the body. If that happens, your external sphincter must work harder to keep you continent.
- NERVE DAMAGE. Incontinence may develop if nerves controlling the sphincters malfunction. Nerve damage can result from childbirth, multiple sclerosis, stroke, diabetic neuropathy or other conditions.
There are new options for treating and managing fecal incontinence. Most people with this distressing condition can get some relief from these treatments. We will discuss them in a future column.
Causes of fecal incontinence
Surgery, constipation, and radiation treatments are among the factors that contribute to fecal incontinence. For example, surgery may cause damage to pelvic floor muscles (A), the pudendal nerve (B), or the anal sphincters (C). Chronic diarrhea or constipation can damage the rectum (D). In women, vaginal childbirth can also damage the anal sphincters, leading to fecal incontinence.