Anorectal manometry

What is it?

Anorectal manometry is a safe, painless and specialised functional test used to assess how the rectum and anal sphincters work. This test is performed only at certain specialist centres and is used for specific indications.

The test shows how the anal muscles work, whether sensations from the rectum are transmitted normally and how the pelvic floor and anal muscles involved in bowel movements are coordinated.

Anorectal manometry can help identify the causes of faecal incontinence, chronic constipation and difficulty passing stool, assess pelvic floor muscle dysfunction and evaluate the effectiveness of treatment. The results can also help determine the most appropriate treatment, including biofeedback therapy.

How should I prepare?

• Fasting is not usually required. You may have a light meal unless your doctor tells you otherwise.
• Your rectum must be empty before the test. Having a normal bowel movement is usually sufficient, although some healthcare facilities may recommend using a micro-enema or small cleansing enema 1–3 hours before the test.
• Take your usual medicines as normal unless your doctor tells you otherwise.
• If you have an acute condition affecting the anus or rectum, such as severely painful haemorrhoids, an acute anal fissure or acute inflammation, tell your doctor in advance.
• If other tests or treatments are also planned, such as a balloon expulsion test or biofeedback therapy, you may be given additional preparation instructions.

How is the test performed?

• The test is performed while you are lying on your left side.
• A thin, flexible catheter containing pressure sensors is gently inserted into the rectum.
• During the test, the doctor will ask you to relax, squeeze your anal muscles, bear down as if having a bowel movement and perform other simple actions.
• In some cases, a small balloon is briefly inflated to assess rectal sensation and capacity.
• The test usually takes 20–40 minutes.

After the test

• You can return to your usual activities and eat and drink immediately after the test.
• No special restrictions are required.
• Your doctor will discuss the results with you and, if necessary, recommend further treatment or additional tests.