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Anorectal Physiology tests

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The thought of having a test on their back passage can be very embarrassing and frightening.  It is however, important to point out to you that these tests are not painful and are only carried out by sympathetic, highly trained professionals who will endeavour to maintain your dignity at all times.  The tests are an important part of the investigation of your bowel condition and will help us to decide the best treatment for your problem.  

Here in Bristol we have concentrated the service at the BRI.  The investigations are performed by either Ann Mills or Katherine Mabey and Lucy Griffin (seen here) in the GI physiology laboratory on level 4.  Ann, Lucy and Katherine are highly experienced and are recognised as a national experts. 

When you arrive to have your tests you will once more be asked a number of questions about how your bowel works and the problems that you have been having.  The tests then take about one hour to complete.

TESTS comprise


This is divided into two parts. You will be asked to lie on an examination couch on your left side with your knees bent.

Anal pressure measurement. This measures the strength of the muscles in your back passage and involves introducing a small tube, about the size of a drinking straw, into your anus. You will be asked to squeeze and relax the muscles and their strength can be measured. 

Rectal sensation and pressure measurements assesses the amount that your rectum can hold. This involves passing another small tube with a balloon attached to it. The balloon is inflated and you will be asked to confirm when you can feel that it is filling up. We will also measure the way the muscles relax using the same tube that was used for the first part of the test.


In some patientswe we will test the function of the nerves controlling the anal sphincter muscles. To do this a small electrode is passed into the rectum on the finger of a rubber glove. This passes a very small electric current over the nerves which will cause the muscles in your back passage to twitch. This procedure can be a little uncomfortable but is not painful.

This test is designed to investigate if there is any numbness in your back passage that might prevent you feeling your motions coming down. A tiny probe attached to a small battery is inserted into your bottom and a small electric current is slowly increased until you can just feel it as a tingling sensation.

Ultrasound scans (pictures) of the muscles of your back passage are taken by passing a finger-sized probe into the anus with you lying on your tummy. This is not painful. This test can demonstrate if there has been any damage done to the anal sphincter muscles eg following childbirth.

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