Anorectal physiology and ultrasound

Why are these tests performed?

These tests are commonly performed for people with incontinence, prolapse and obstructed defaecation syndrome.  They are standard tests that give information regarding the function and structure of the anal canal and lower rectum.

What is anorectal physiology and ultrasound?

Anorectal physiology is an investigation that assesses the strength of the muscles in the anal canal, and also checks the sensitivity of the rectum to small volumes of air and its response to distension.
The investigation takes about 45 minutes to perform.  The physiologist will ask you some detailed questions about your symptoms to tailor the tests to your problem.  The investigator will perform a gentle rectal examination to check that the rectum is empty and that you are able to push and squeeze when requested during the test.
A small catheter (tube) is placed inside your rectum and a device used to gently withdraw it at a steady rate, measuring the strength of the anal sphincter muscles.  This is done three times with you relaxed and three times with you squeezing your anal muscles.
Next, a small balloon is attached to the end of the catheter and placed into your rectum.  Small volumes of air will be introduced into the balloon and you will be asked to record your sensations as this is done.
The ultrasound part of the test assesses the structure of the anal sphincter muscles and the lower rectum. An ultrasound probe is inserted into the anal canal; the probe, which is the same thickness as a pen, usually has to go in no more than 5cm (2 inches).
At this point the investigator will usually analyse the results obtained so far and discuss the findings with you.

What special preparation is there?

No special preparation is necessary; we would ask you to refrain from eating or drinking for two hours before the test and, if possible, to have had your bowels open on the day of the test.

What happens after my test?

You will usually be completely comfortable after the tests and able to drive home and/or go back to work immediately.  Once the tests are done, the investigator can explain the basic findings to you but will not offer a diagnosis.  A report will be sent to your consultant who will give you a diagnosis and discuss treatment at a future appointment.

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