Anorectal manometry is a test used to assess how well the rectum and anal sphincter are working. These two components work together to control the passing of stool. This test is used for patients who have difficulty passing stool (constipation) or fecal incontinence (leakage of stool). A small flexible tube with a balloon on the end is inserted into the rectum. The balloon is gradually inflated to mimic a bowel movement. A small computer records the pressure exerted on the small tube and this allows your doctor to better determine the cause of your symptoms.