Intrapartum predictors of maternal levator ani injury

Introduction: Damage to the pelvic floor during vaginal childbirth is common, and may take the form of levator avulsion or irreversible overdistension of the levator hiatus (microtrauma). Such trauma is a major risk factor for pelvic organ prolapse later in life. In this study we aimed to identify intrapartum risk factors for levator trauma. Material and methods: This is a retrospective analysis of data obtained in two perinatal studies on primiparous women. Between 2005 and 2014, 1148 women carrying an uncomplicated singleton pregnancy in the late third trimester were seen for 4D pelvic floor ultrasound and an interview. They were invited for a repeat assessment at three months postpartum. Results: Of 1148 women, 871 (76%) returned for assessment at a mean of five months postpartum. The datasets of 844 women were analyzed due to missing data or concurrent pregnancy in 27. In all, 452 (54%) had a normal vaginal delivery, 102 (12%) a vacuum, 55 (6%) a forceps, and 235 (28%) a cesarean section. On multivariate analysis forceps, length of second stage and obstetric anal sphincter tears were significantly associated with levator avulsion. There were no significant predictors identified for irreversible overdistension. Conclusions: The use of forceps, a prolonged second stage, and obstetric anal sphincter tears were associated with levator avulsion. There were no associated intrapartum predictors for hiatal overdistension.