Everything You Need to Know About Anorectal Manometry

Anorectal manometry is a non-invasive procedure that measures muscle contractions in the anal and rectal muscles to determine if they activate and coordinate correctly. It is typically performed to find the cause of fecal incontinence or chronic constipation.

This article discusses everything you need to know about anorectal manometry, from how it's done to the meaning of results.

Woman talking to doctor

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Who May Need Anorectal Manometry?

Specialized muscles must work together to have healthy bowel movements. In conditions like fecal incontinence or constipation, the muscles are not contracting or have the strength to do what is needed to release the bowels properly. Constipation and fecal incontinence are the most likely conditions to require anorectal manometry.

People with other health disorders and symptoms may also need the procedure. Specific issues that may require an anorectal manometry include:

What is Fecal Incontinence?

Fecal incontinence occurs when the muscles of the anus do not contract when they should, leading to a loss of control of the bowels and the unintentional release of fecal matter. In some cases, fecal matter can leak out of the anus without a person noticing.

How Does Anorectal Manometry Work?

Anorectal manometry uses a tool known as a manometer, which is an electromechanical device that measures pressure. The procedure measures the pressure of the anal or rectal muscles contracting to test for their strength or weakness, how long it takes them to trigger, and whether or not they turn on at the right time.

How Does the Manometer Work?

The manometer is a catheter-like tube with several pressure sensors designed to gauge the pressure within the anus and rectum. It is inserted into the rectum and anus. The end of the tube has a deflated balloon that is inflated while inside the rectum. This inflation is designed to activate specific nerves within the body to stimulate the muscles.

How to Prepare for an Anorectal Manometry

On the morning of an anorectal manometry, you will eat a light breakfast and avoid consuming food or drinks (except water) until the procedure. The rectum and anus must be clear of fecal matter, so refraining from overeating helps get accurate results.

You will also have to perform two saline enemas at least two hours before the procedure begins to stimulate a bowel movement. This will help clear the area so that the manometer can be easily inserted into the rectal cavity.

What Else Can I Do to Help Get Accurate Results?

Your healthcare provider may have further instructions for you to follow. For example, some types of medications may need to be adjusted beforehand. If you take any of these drugs, you must follow the instructions given by a healthcare provider before undergoing the procedure.

What Happens During the Anorectal Manometry Procedure?

No anesthesia is required for an anorectal manometry procedure because it is relatively simple and non-invasive. During the procedure, several things will happen, including:

  • The insertion of the manometer into the anus and rectum
  • The balloon on the end of the manometer will be inflated and deflated with air to determine how the muscles contract
  • The pressure data is sent to a computer, where it can be analyzed

During the procedure, the healthcare provider conducting the test may also ask you to squeeze, push, or relax the muscles in your anus and rectum at various points throughout the get different readings.

How Long Does an Anorectal Manometry Take?

Typically, the entire procedure takes only 30 minutes, but it can range from 15 to 45 minutes depending on how much information is needed and the readings they get during. Once it has finished, you can continue your regular daily activities.

Is Anorectal Manometry Painful?

Anorectal manometry may come with some level of discomfort, but it is not typically painful. The manometer tool is roughly the size of a thermometer. Because of its small size, pain should not be felt when it is inserted into the anus and rectum.

What Is a Balloon Expulsion Test?

Along with anorectal manometry, a balloon expulsion test may be performed to help reach a better diagnosis. The test involves inserting a small balloon in the anus and rectum and then filling it with water. Once inserted and filled, you are asked to try to have a bowel movement in the bathroom.

Healthcare providers measure and record how long it takes you to defecate or expel the balloon after going to the bathroom. If a person takes a longer time, it is determined that there is likely an issue with how the anus and rectum are functioning.

Why Do I Need More Than One Test?

While not everyone will be required to do more than one test for any anal or rectum issues, it is necessary in some cases so that healthcare providers can paint a better picture of what’s going on. That way, they can reach the proper diagnosis and, thus, develop the appropriate approach to care.

Are There Risks or Side Effects to Anorectal Manometry?

Typically, anorectal manometry is safe and effective. The chances of an adverse event are low, but they are not non-existent. Some rare but possible side effects can include:

What Will the Results of an Anorectal Manometry Show?

The results of an anorectal manometry can show several things because the main reason for the test is to determine why a person is experiencing chronic constipation or fecal incontinence. Some possible issues that may come to light after the procedure include:

  • Weak anal sphincter muscles
  • Poor sensation in the rectum, making it harder to feel if a bowel movement needs to be made
  • An inability for the anal sphincter muscles to relax

Results and Next Steps

Once healthcare providers have the results they need, they can look at possible treatments depending on what they find. Because there are several causes of chronic constipation and fecal incontinence, it’s crucial to get a proper diagnosis, and the results of anorectal manometry can help.

Does Anorectal Manometry Lead to Effective Diagnosis and Treatment?

Anorectal manometry can help with diagnosis and treatment in many cases. Other tests or examinations may also be performed because healthcare providers will need to be sure they know what’s happening in the anus and rectum before they can treat it.

If the issues are with muscles and nerve communication alone, biofeedback may be suggested to help retrain the muscles. Physical therapy is also a viable option for treating problems caused by changes in how the anus and rectum muscles act.

Summary

Anorectal manometry is a non-invasive and often pain-free procedure used to help diagnose issues that affect gastrointestinal health. Fecal incontinence and chronic constipation are the most common reasons to get an anorectal manometry, but it can be used to determine other disorders that affect the health and function of the rectum and anus. People undergoing the procedure can expect relatively low discomfort and return to their daily activities once it is done.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Lee TH, Bharucha AE. How to perform and interpret a high-resolution anorectal manometry test. J Neurogastroenterol Motil. 2016 Jan 31;22(1):46-59. doi:10.5056/jnm15168

  3. UCLA Health. Anorectal manometry test preparation instructions.

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  5. Rao SSC, Ahuja NK, Bharucha AE, Brenner DM, Chey WD, Deutsch JK, Kunkel DC, Moshiree B, Neshatian L, Reveille RM, Sayuk GS, Shapiro JM, Shah ED, Staller K, Wexner SD, Baker JR. Optimizing the Utility of Anorectal Manometry for Diagnosis and Therapy: A Roundtable Review and Recommendations. Clin Gastroenterol Hepatol. 2023 Oct;21(11):2727-2739.e1. doi:10.1016/j.cgh.2023.05.025

Angelica Bottaro

By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.