Testing - Fecal Incontinence: Bladder Conditions

Content provided by the Faculty of the Harvard Medical School

Testing

After your physical, you may be scheduled for additional tests.

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 called a sigmoidoscope, for example, 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. It is often used to screen for colon polyps and other signs of colon cancer. This test requires sedation and is usually not necessary to evaluate fecal incontinence, but it may be suggested if colorectal cancer is suspected or if a screening colonoscopy might be advisable anyway.

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

If your doctor believes that constipation may be causing your incontinence, a standard abdominal x-ray may help reveal the problem.

Defecography. To evaluate the anatomy and functioning of your pelvic floor muscles and rectum, or if an obstruction in the colon is suspected, you may undergo a specialized x-ray exam called defecography, dynamic defecography, or evacuation prostography, an exam that is comparable to the use of cystography in evaluating urinary incontinence. Before your appointment, you clean out your colon as you would for sigmoidoscopy. One hour before the exam, you may be asked to drink some barium solution, or a similar solution may be introduced into your rectum.

Just before the exam, a substance with the consistency of stool that is visible on x-ray is inserted into the rectum and vagina. Then the technician takes x-ray video images as you cough, squeeze your buttocks, strain, and defecate on a special commode. This test can reveal abnormal positioning of the rectum or relaxation of sphincter muscles. The exam is not painful, but you may have an uncomfortable feeling of needing to have a bowel movement.

Other tests

Even if nothing is apparent on the clinical exam and you don't recall a difficult childbirth or other trauma, your doctor may still suspect that your anal sphincters are damaged. The following tests can help determine whether that is the case.

Endoanal ultrasound. This technique, also known as endoanal sonography, uses sound waves, rather than x-rays, to create images of the internal and external anal sphincters. Inserting a slim ultrasound probe into the anus, the physician should be able to see how your sphincter muscles move and whether any portions of the muscles are missing or have become too thin.

Distinguishing incontinence caused by sphincter damage, which may be surgically repairable, from that caused by other muscle or nerve damage can be crucial in planning therapy. Endoanal sonography can help distinguish who will benefit from surgery and who might best respond to nonsurgical approaches.

Magnetic resonance imaging (MRI). As an alternative to ultrasound, some physicians have begun using MRI to examine the sphincters. MRI uses a magnet and radio waves to create detailed cross-sectional images. For this exam, you lie very still on a table that is rolled into the opening of a tunnel-shaped magnet. It is not yet proven that the added expense of MRI provides a more accurate diagnosis. One study that compared the diagnostic accuracy of MRI versus ultrasound found little difference between the two.

Anorectal manometry. The clinician uses this test to measure the pressure inside your rectum and anal sphincters, equivalent to urodynamic testing for urinary incontinence. After you use an enema, the clinician inserts into your rectum a small flexible tube (about the width of a rectal thermometer) with a deflated balloon at the end. The pressure inside your rectum and inside each sphincter is recorded on a polygraph-like display as you rest, squeeze, and bear down as if trying to expel a bowel movement. This testing helps the clinician assess both the strength of your sphincters and whether they are relaxing and constricting at the proper times.

Anorectal electromyography (EMG). This test helps assess whether your nerves are properly able to control the action of your anal sphincters. For an anal sphincter EMG, a small electrode-containing sponge is inserted into your anal canal to record electrical signals from the sphincter muscles as you squeeze and relax. For a pudendal nerve study, the clinician does a digital rectal exam with a small electrode attached to deliver a mild electrical current to the pudendal nerve. The amount of time it takes for the sphincter to contract in response to the current is measured.

Last updated:	September 05, 2008