The anorectal manometry procedure, or ARM, is used to evaluate the muscle tone of the internal and external anal sphincter muscles, the ones that control bowel movements and prevent leakage of stool.
This diagnostic test is commonly used to assess bowel movement issues such as chronic constipation, fecal incontinence or a failure of the muscles to relax during defecation, a condition known as anismus or dyssynergic defecation.
The Anorectal Manometry Procedure
The anorectal manometry procedure involves the use of a flexible tube that contains a small balloon at one end. The end with the balloon is inserted into the rectum and the other end is attached to a machine that measures the pressure of the anal sphincter. The balloon is then slowly and carefully inflated to various sizes. This allows the machine to measure the actions of the anal sphincter muscles and its varying pressure when flexed and relaxed.
The anorectal manometry procedure measures:
- Strength and movement of the anal sphincters
- Sensation of stool in the rectum
- Normality of reflexes that control bowel movements
During the procedure, which normally lasts from 30 to 45 minutes, the patient may be asked to relax or tighten their sphincter muscles. In some cases this test is performed on children as well as adults.