Quick answer
Anorectal manometry is a test that evaluates how the rectum and anal sphincter muscles and nerves function during bowel movements. It can measure pressure, sensation, reflexes and the coordination involved in emptying the bowel. A clinician may recommend it when symptoms suggest a problem with bowel-emptying mechanics or continence. The result is interpreted alongside symptoms and other findings; it is not a diagnosis on its own.
What is anorectal manometry?
Anorectal manometry is a functional test of the lower bowel outlet. It focuses on how the rectum and anal canal respond when a person rests, squeezes, relaxes or tries to pass stool. It is different from a camera-based test that looks at the lining of the digestive tract.
The test uses a thin, flexible catheter with pressure sensors. Depending on the test system, a small balloon may be attached to assess rectal sensation or the response to a simulated bowel movement. The equipment records pressure patterns while the patient follows instructions from the clinical team.
Why might a clinician recommend the test?
Anorectal manometry may be considered when a person has persistent difficulty passing stool, a feeling of incomplete emptying, straining that does not resolve, or problems controlling bowel movements. It may help assess whether the muscles are generating pressure and coordinating in the expected way.
It is not a routine test for every episode of constipation, abdominal discomfort or change in stool. A clinician first considers the history, examination, medicines, previous procedures and other possible causes. The decision to test depends on the symptoms and the clinical question being asked.
What does anorectal manometry measure?
Anal sphincter pressure. The test records pressure at rest and during a voluntary squeeze. This helps assess how the anal sphincter muscles respond.
Rectal sensation. If the protocol includes balloon inflation, the patient may be asked when they first feel the balloon and when the sensation becomes stronger. This provides information about rectal sensitivity.
Reflex responses. The test may record automatic pressure changes that occur when the rectum is distended.
Coordination during attempted evacuation. The patient may be asked to bear down as though having a bowel movement. The recording helps the clinical team assess whether the muscles relax and coordinate appropriately.
Some centres may add a balloon expulsion test. This is a separate step that assesses the ability to expel a small inflated balloon under the test protocol. Not every patient or test pathway includes it.
What happens during the procedure?
The exact process varies by centre and equipment. In many protocols, the patient changes into a gown and lies on their side. A trained healthcare professional performs the test according to the planned protocol and explains each instruction.
A lubricated, thin catheter is inserted a short distance into the rectum. The patient may be asked to squeeze, relax, cough or bear down while the system records pressure. If a balloon is used, it may be inflated in stages to assess sensation or evacuation response. The procedure is generally performed without an incision, but the patient should ask the clinical team what to expect in their specific case.
Some people feel pressure, fullness or embarrassment during the test. It is reasonable to tell the team if there is pain, anxiety, previous anorectal surgery or another concern before the procedure begins.
How should a patient prepare?
Preparation instructions depend on the clinical question, the centre’s protocol and the patient’s medical history. The team may provide instructions about bowel preparation, food, medicines or the timing of the test. Follow the instructions given for the scheduled test rather than using a preparation list found online.
Do not stop prescription medicines, laxatives or other treatments unless the clinician specifically tells you to. Tell the team about previous bowel or pelvic surgery, current bleeding, significant pain, allergies, pregnancy or other relevant medical conditions. Ask whom to contact if the preparation instructions are unclear.
What do the results mean?
The report may describe pressure at rest and during squeeze, rectal sensation, reflexes and the pattern observed during attempted evacuation. These findings help the clinician decide whether the test suggests a functional difficulty that needs further evaluation.
A result should not be interpreted from one number alone. Normal ranges can depend on equipment, technique, age and the laboratory’s reference data. Symptoms, examination findings and other investigations may all be needed before a diagnosis or management plan is made.
Anorectal manometry vs colonoscopy: what is the difference?
Anorectal manometry assesses the function and coordination of muscles and sensation around the rectum and anus. A colonoscopy uses a camera to examine the inner lining of the large intestine. These tests answer different clinical questions and are not interchangeable. A clinician decides which investigation, if any, is appropriate for a person’s symptoms.
Readers who want a broader overview of digestive investigations can review the guide to tests for gut health. Factual information about the investigations listed under gastroenterology, including anorectal manometry, appears on the gastroenterology service information page. The service link is included for navigation only and must be reviewed under the applicable institutional communication requirements before publication.
When should symptoms be discussed promptly?
Seek medical advice for persistent bowel-emptying difficulty, new or ongoing loss of bowel control, unexplained changes in bowel habit or symptoms that are affecting daily life. Significant rectal bleeding, black stools, severe abdominal pain, fever, fainting or rapidly worsening symptoms require prompt medical assessment. A test should not delay urgent evaluation when warning signs are present.
Frequently asked questions
Is anorectal manometry painful?
Many people describe pressure or discomfort rather than pain, but the experience varies. Tell the clinical team if you feel pain or need the procedure explained or paused.
How long does anorectal manometry take?
The duration depends on the equipment and whether additional steps, such as a balloon expulsion test, are included. The centre performing the test can explain the expected appointment time.
Does anorectal manometry diagnose constipation?
It helps assess muscle pressure, sensation and coordination in selected patients. The result is considered alongside symptoms and other findings; it does not explain every cause of constipation.
Is anorectal manometry the same as colonoscopy?
No. Manometry measures function and pressure around the rectum and anus. Colonoscopy uses a camera to examine the lining of the colon.
Should I stop my medicines before the test?
Do not stop any medicine unless the clinician or testing centre specifically instructs you to. Preparation varies by patient and protocol.
Disclaimer
This article is for general health education only. It does not provide a diagnosis, recommend a test for an individual or replace consultation with a qualified healthcare professional. Test suitability, preparation and interpretation depend on the patient’s clinical circumstances and the protocol used.