Anorectal manometry is a test that measures the functional performance of the anus and rectum. Using a small catheter and a balloon with sensors, it measures the pressures of the anal sphincter muscles, the sensation in the rectum, and the neural reflexes that are needed for normal bowel movements.
This test is usually recommended to evaluate patients with generalized bowel dysfunction. This could include those experiencing chronic constipation or fecal incontinence.
In some patients with chronic 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 anal manometry.
In addition, weak anal sphincter muscles or poor sensation in the rectum can contribute to some cases of 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.
You will change into a hospital gown and be asked to lie on your left side. A small, flexible catheter with pressure sensors and a balloon on the end will be gently inserted into the rectum. During the test, the balloon will be inflated in the rectum to assess the normal reflex pathways. The nurse may also ask you to squeeze, relax, and push at various times in order to measure the anal sphincter muscles.
The test takes approximately 30 minutes and is unlikely to cause any pain.
You will be asked to administer an enema at home on the day of the test. A nurse will instruct you about the amount and type of enema to be used. In addition, you should not eat anything two hours prior to the test.