Also called rectal sphincter repair, is the most common procedure used to correct a defect in the anal sphincter muscles. There are two anal muscles that control bowel movements, similar to two round doughnuts, one inside of the other. If a defect exists in the complete circle of muscle, the problem can be corrected with this surgery. During the sphincteroplasty, the two ends of the muscle are cut and overlapped onto one another, then sewn in place. This procedure then restores the complete circle of muscle.