This test measures how well the muscles that control the opening and closing of the anal sphincters and the rectum are working together to eliminate waste. Some of the reasons to have an anal manometry test include difficulty passing stool, constipation or the inability to control bowels resulting in feces leakage. After this test, which employs a small catheter to determine the tone of those muscles, the Methodist Hospitals gastroenterologist interprets the findings of a report that lists the measurements gathers and recommends treatment.