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Anorectal Manometry

What is anorectal manometry?

Anorectal manometry is a test performed to evaluate patients with constipation or fecal incontinence. This test measures the pressures of the anal sphincter muscles, the sensation in the rectum, and the nerve reflexes that are needed for normal bowel movements.

To prepare for the test:

Take one (1) Fleets enema 2 hours prior to your appointment. Fleets enema is an over the counter medication and can be bought at your drug or grocery store.

The test:

The test will take about 30 minutes and will be done in the office. A nurse or medical assistant will take vital signs, verify medical information in your record, explain the test to you and answer any questions. You will be asked to disrobe from the waist down so dress in 2 piece clothing. You will lie on your left side during the test. A small, flexible tube with a balloon on the end will be inserted into your rectum. The small tube is connected to a machine that will measure the pressure. During the test, the small balloon on the tube will be inflated in the rectum to assess the strength of the rectal muscles. The nurse or medical assistant will ask you to squeeze, relax, push, or cough at various times. After the test, you may drive yourself home and go about your normal activities.

What can be learned from the test?

The anal and rectal area contains specialized muscles that are helpful to regulate proper passage of bowel movements. Normally, when stool enters the rectum, the anal sphincter muscle tightens to prevent passage of stool at an inconvenient time. If this muscle is weak or does not contract in a timely way, incontinence (leakage of stool) may occur.

Normally, when a person pushes or bears down to have a bowel movement, the anal sphincter muscles relax. This will cause the pressure to decrease allowing evacuation of stool. If the sphincter muscles tighten when pushing, this could contribute to constipation.

Anal manometry measures how strong the sphincter muscles are and whether they relax as they should during passing a stool. It provides helpful information to the doctor in treating patients with fecal incontinence or severe constipation.

There are many causes of fecal incontinence. Weak anal sphincter muscles or poor sensation in the rectum can contribute to fecal incontinence. If these abnormalities are present, they can be treated. Biofeedback techniques using anal manometry and special exercises of the pelvic floor muscles can strengthen the muscles and improve sensation.

There are many causes of constipation. Some involve sluggish movement through the whole colon, whereas others involve the anal sphincter muscles. In some patients with constipation, the anal sphincter muscles do not relax appropriately when bearing down or pushing to have a bowel movement. This abnormal muscle function may cause a functional type of obstruction. Muscles that do not relax with bearing down can be retrained with biofeedback techniques using an anal manometry.

Risks of Anorectal Manometry:

Anorectal manometry is a safe, low risk procedure and is unlikely to cause any pain. Complications are rare: it is possible that a perforation (tearing) or bleeding of the rectum could occur. Equipment failure is a remote possibility. If you are allergic to latex, you should inform the nurse or medical assistant before the test so that a latex-free balloon can be used.