What is Anorectal Manometry?

Anorectal Manometry is a diagnostic test performed to evaluate how well the rectum and anal sphincter are working.The rectum is the final segment of the large intestine that connects the colon to the anus. It is here that the faeces are temporarily stored before being excreted through the anus. Anus is the opening at the end of the digestive tract through which solid waste matter leaves the body. Two anal sphincters ( circular ring-like muscles ) control the exit of feces during the act of defecation.

When the rectum becomes full, the increase in intrarectal pressure forces the walls of the anal canal apart and peristaltic waves propel feces from the rectum into the anal canal. The anal sphincters finally allow the exit of the feces out of the body.

Manometry is done in cases of constipation, fecal incontinence and other anorectal diseases. It gives an idea of how well the rectum and anal canal are working

anorectal diseases treatment

What is the need for doing a Manometry? ( Principle behind the test )

The rectum and anal canal contain muscles that relax and contract to regulate proper passage of feces. When feces enter the rectum, there is an urge to defecate. In case the situation does not allow one to answer the call, the anal sphincter muscles tighten to prevent passage/leakage of stools ( failure of which causes incontinence ). Conversely, when one is having a bowel movement, the anal sphincter muscles relax to allow passage of feces ( in some cases of constipation this relaxation is impaired ).

Anal Manometry assesses how the rectum responds to increased pressure ( inflated balloon ). It also measures how strong the sphincter muscles contract and whether they are able to relax adequately when needed.

How is the test performed?

  • You will be asked to lie on your left side
  • A thin flexible tube with a small uninflated balloon at the tip is passed through the anus up to the rectum. The other end of the tube remains outside and is attached to a machine that records the pressure changes.
  • You will be asked to inform when you sense a feeling of fullness ( similar to the defecation urge ). You will also be asked to push with your anal muscles ( as in trying to defecate ) and to squeeze the anal muscles
  • The procedure takes about 20min. It is painless and easily tolerated. You may go home immediately after the procedure.