Risk Factors for and Repair of Obstetric Anal Sphincter Injuries

Obstetric anal sphincter injuries occur in 4% or less of vaginal deliveries, but the potential downstream consequences of the injury (most commonly anal incontinence) can drastically alter a person's quality of life. The main risk factors for obstetric anal sphincter injuries are those that contribute to difficult vaginal birth and the need to perform an operative vaginal delivery (most notably forceps-assisted vaginal delivery). Successful repair of an obstetric anal sphincter injury is achieved with a thorough understanding of the perineal and perianal anatomy and careful attention to layer-by-layer reconstruction. Close follow-up of patients who sustain obstetric anal sphincter injuries can help identify possible complications earlier in their course. For patients who are considering subsequent pregnancy and delivery, there should be a thoughtful, patient-centered discussion, recognizing that, although cesarean delivery can prevent recurrent sphincter laceration itself, it has its own immediate surgical and future pregnancy risks and is not guaranteed to prevent anal incontinence.