Sphincteroplasty: the surgical reconstruction of a sphincter muscle. This usually refers to the procedure that can be done on the muscles of the anal sphincter that control bowel movements.With obstetric trauma during vaginal delivery of a baby, this sphincter can become damaged and result in incontinence of stool.ith rectal or anal sphincter repair, the ends of the two circular anal muscles that control bowel movements are cut and overlapped onto one another and then sewn into place, creating a complete circle of muscle.