What is anorectal manometry?
Anorectal manometry is a test that measures the pressure of the anal sphincter muscle and the reactivity of the last segment of the large bowel, called the rectal ampulla.
This test is useful in the following cases:
- As a routine examination before interventions for the treatment of perianal fistulas.
- As a routine examination before proctological operations involving anastomosis.
- To investigate complications arising after anorectal operations
- As a diagnostic test (often complementary) for some disorders of the last digestive tract.
Anorectal manometry measures the functionality of the anus and rectum.
What does it consist of?
The Digestive tract specialist inserts a 0.5cm diameter cannula into the anus and pushes into the rectum to a depth of approximately 10cm.
The cannula detects the pressure and the nature of the movements made by the muscles of the anus; a balloon at the end of the cannula is then slightly inflated to analyze the reactivity of the rectal ampulla. This information is recorded by a machine connected to the probe.
The test takes a total of half an hour and does not require anesthesia.
Why is it performed?
It is not a first level diagnostic method. It is usually used after other types of tests (e.g., X-ray and endoscopy) have been performed, to gather more information and to examine the evolution of disorders such as:
- Constipation: the test can diagnose pathologies such as congenital megacolon and Hirschsprung’s disease.
- Difficulty in defecation: anorectal manometry analyzes any possible disorder of the anus musculature, such as anal hypertonia, anismus, anorectal dyssynergia, etc.
- Anal incontinence or diarrhea: examination can help distinguish between tenesmus, diarrhea, fecal incontinence, etc.
- Anal spasms
- Prolapse of the rectum, fissures, hemorrhoids.
- Complications arising after surgery: in this case, comparison of the information obtained by several different manometries (one performed before the operation and the other after) can help to determine whether the complications arising after the operation are in fact due to the latter or not.
- Neurological lesions: anorectal manometry can diagnose possible neurological causes of disorders such as hypotonia or secondary or anal hypertonia; in this case, the manometric examination will be completed with other previously performed functional tests suggesting the presence of neurological lesions.
Preparation for anorectal manometry
The patient should undergo a voiding enema about 2 hours before the test, but it is not necessary to fast or stop any treatment or discontinue any medication being taken. The results of any previously performed diagnostic tests and other documents considered relevant should be brought to the examination.
After this test, the patient may leave the clinic alone.
What does the test feel like?
Anorectal manometry is not painful. The discomfort felt by the patient is minimal as the probe used is very thin and does not go deep into the rectal canal. It is a fairly simple test, which hardly involves contraindications.