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Anorectal Physiology

What is anorectal physiology testing?

Anorectal physiology testing enables a medical specialist to determine the possible cause/s of conditions such as faecal incontinence, constipation or any difficulty in having a bowel motion.

How is the testing conducted?

There is no surgery involved in any of the procedures outlined here (and thus no anaesthetic is needed) and all testing is carried out on an outpatient basis. Prior to the tests – ideally at home before leaving for the test – the patient may need to use a Microlax enema (you will be advised if this is necessary).

What is involved in the tests?

Pressure inside the anus and rectum is measured in a diagnostic procedure known as 'anal manometry', where small tubes are inserted into the anus. The patient will be asked to cough, or squeeze/strain and the test will gauge the response of the muscles in the anus.

In some cases, other diagnostic procedures may be required, for example a 'rectal balloon filling', 'pudendal nerve study' or endoanal/endorectal ultrasound.

The ultrasound tests allow the medical specialist to see if there is a tumour or fistula present and to check whether the anal sphincter muscle is working as it should. An ultrasound test is conducted by inserting a special probe into the anus, which then provides a very detailed image of the anal and rectal walls.

Each test generally takes no more than 15 minutes to complete.


The following risks are rare:

  • Minor bleeding (often noticed as spotting e.g. on toilet paper) - this generally does not last long.
  • Latex - if the patient has a latex allergy (please let us know if you know you have a latex allergy).


Anorectal physiology is generally not conducted during the first 12 weeks of pregnancy.