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How is fecal incontinence diagnosed?

Anthony L. Komaroff, MD
Internal Medicine

The following tests may be recommended by your doctor to help diagnose fecal incontinence (unintended passage of stool):

  • Laboratory tests: If the doctor suspects an infection is causing diarrhea, he or she may take a stool sample and have it cultured in the laboratory so it can be examined for bacteria or other microbes. Other laboratory tests may be used to rule out various conditions that can have fecal incontinence as a symptom.
  • Exams using scopes: The doctor may want to use a scope to take a closer look at the area suspected of causing the problem. Using a viewing device, such as a sigmoidoscope, your physician can check for tumors, inflammation, prolapse, or other changes in the lining of your lower colon or rectum that might indicate damage to underlying nerves and muscles.
  • Flexible sigmoidoscopy. This test can be performed in your physician's office or in the hospital. You'll receive instructions in advance on how to clean out your bowels -- usually by fasting and taking a laxative the night before the test and using an enema an hour or two before your appointment. While you lie on your side, the doctor inserts a lubricated flexible scope (about half an inch wide and 2 feet long) through your rectum into your colon. The scope has a light and video camera, along with mechanisms for adding air or washing the area to get a better view. The exam takes about 20 minutes.
  • Colonoscopy. Using this method, the doctor examines the full length of the colon. This method is often used to screen for colon polyps and other signs of colon cancer. The test requires sedation. It is usually not necessary to evaluate fecal incontinence, but it may be suggested if colorectal cancer is suspected or if screening might be advisable for other reasons.
  • Other scope exams. For an examination that does not include the colon, your physician may use a proctoscope to examine the rectum or an anoscope to view the anal canal only.
  • X-rays: Rarely, special x-rays may be taken to help evaluate the anatomy and functioning of your pelvic floor muscles and rectum or to locate any obstruction in the colon. These exams go by different names: defecography, dynamic defecography, or evacuation proctography.

Fecal incontinence is typically diagnosed by your symptoms, a medical history, and sometimes a physical exam. The doctor will need to know how often your symptoms occur and what circumstances surround the occurrences. Various diagnostic tests can help your doctor confirm fecal incontinence and find its cause. Your doctor may examine your rectum with their finger to evaluate the strength of your sphincter muscles and look for problems like rectal prolapse. Your doctor may perform an anal manometry to measure the amount of pressure your sphincter muscles are capable of producing. Other tests you might undergo include proctography (also called defecography), proctosigmoidoscopy, anal electromyography and anorectal ultrasonography,.

To diagnose fecal incontinence, physicians conduct a number of tests, including anal manometry, which measures the strength of the anal sphincter muscles and their ability to respond to signals. An MRI and/or an anorectal ultrasound may also be done to visualize the structure of the sphincters. Proctography (also known as defacography) shows how much stool the rectum can hold, how effectively it holds it, and how effectively the rectum can evacuate. Proctosigmoidoscopy enables the physician to view the inside of the rectum and lower colon to detect disease or other problems such as inflammation, scar tissue, or tumors, which can cause fecal incontinence. An anal electromyography, which uses tiny needles to measure nerve damage, may also be done for nerve damage caused by injury during childbirth.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.