This is an investigation to look at how the anus and rectum are functioning.  The main indication is in patients with incontinence.  It is sometimes used in patients who find it very difficult to open their bowel. 

The test involves insertion of a probe (about the size a thin rope) into the anus. The probe is connected to a pressure transducer. The pressure in the anus is measured at rest, when the patient tightens their anus and when they push out.  These measurements tell a lot about the integrity of the sphincter muscles.

Other parts of the tests include putting a balloon in the rectum and blowing some water in it. This tests the volume of water needed to have a feeling of wanting to open the bowels and then the volume of water needed to initiate evacuation. Through these tests, the relationship between the anus and the rectum in the initiation of incontinence is assessed.

An adjunct to this is endo-anal ultrasound (EAUS).  This is an ultrasound that looks at the physical state of the sphincter muscles. This looks for defects in the muscles and helps determine what the plan for treatment will be. It can be used  to assess damage caused by childbirth, surgery and other causes.  EAUS is also used to assess the stage of tumours.