If you require an ano-rectal manometry, you’ll have to fast for a certain number of hours before the procedure and take enemas to clean out your digestive system. During the procedure, a narrow tube is inserted into the rectum. The tube is connected to a computer that provides readings for your doctor to evaluate. A small balloon on the end of the tube may help measure reflexes. You alternately relax, squeeze and push (as if you were having a bowel movement). The test takes only about 30 minutes, and you’ll feel minor discomfort, if any.