What is anorectal manometry with balloon expulsion test?
Anorectal manometry is a simple test that measures how well the muscles and nerves in your rectum and anus work. The balloon expulsion test checks how easily you can push out a small balloon from your rectum. These tests are often done together to understand why you may have constipation or difficulty with bowel movements.
Health care providers use these tests to find out if your muscles and nerves are working properly when you try to have a bowel movement. They help diagnose conditions like chronic constipation, pelvic floor problems, or difficulty controlling bowel movements.
How to prepare for anorectal manometry with balloon expulsion test
There are important steps you must take to safely get ready for your upper anorectal manometry with balloon expulsion test.
These are general instructions. Be sure to follow any instructions given to you by your health care provider.
Your doctor or nurse will review the steps with you and make sure that you know how you need to get ready and what you can expect during and after the test. If you have any questions, be sure to bring them up with the doctor or nurse.
- Give your doctor a list of all the medications you are taking and any allergies you have. The list should include both prescription and over-the-counter (OTC) drugs like aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), or vitamins or supplements.
- Ask your doctor before the test if any of your medications should not be taken.
- Clear your rectum: You may be asked to use an enema a few hours before the test.
- Wear comfortable clothing.
What to expect during anorectal manometry with balloon expulsion
The test is usually done in a clinic and takes about 20–30 minutes. Your health care provider will tell you more specifically what you can expect during the test. Some things may include:
Before your anorectal manometry with balloon expulsion
- A nurse will review your medical history, medications, and allergies.
- You will change into a hospital gown.
- Your doctor will review the consent form for the test, answer any of your questions, and may ask you to sign the form, which says you understand the test being done.
During your anorectal manometry with balloon expulsion
- You will lie on your side or sit on a portable toilet while a thin, flexible tube is gently placed into your rectum.
- The tube has sensors to measure muscle pressure and a small balloon at the tip.
- The health care provider will ask you to squeeze, relax, and push to check how your muscles work.
- For the balloon expulsion test, the balloon is filled with warm water, and you will be asked to push it out like a bowel movement.
- The test is not painful, and no anesthesia is needed.
What to expect after anorectal manometry with balloon expulsion
You can go home right after the test and return to normal activities. Your health care provider will review the results with you and explain what they mean. These tests help guide the best treatment for your symptoms.
Kyle Staller, MD, MPH
Director, Gastrointestinal Mobility Laboratory, Massachusetts General Hospital, Boston
Reviewed November 2025