Levator ani muscle injuries associated with vaginal vacuum assisted delivery determined by 3/4D transperineal ultrasound

Abstract

Objectives: To determine the rate of pelvic floor trauma, levator ani muscle (LAM) avulsion as well as the mean difference in levator hiatus area, after normal vaginal deliveries (NVD) and vacuum assisted deliveries (VD), assessed with three-dimensional transperineal ultrasound (3D-TpUS).Materials and methods: Prospective observational study with 151 nulliparous women with NVD or VD at ≥37 weeks between 9-2012 and 6-2013. 3D-TpUS was performed six months after every patient’s delivery, during which LAM, anteroposterior diameter, transverse diameter and levator hiatus area were assessed.Results: A total of 146 nulliparous were studied, comprising 73 NVD and 73 VD. No differences in obstetric, intrapartum or neonatal characteristics were observed between study groups, with the following exceptions: maternal age (28.1 ± 5.4 versus 30.4 ± 5.5; p = 0.008, OR = 1.1) and episiotomy rate (35.6% versus 97.3%; p = 0.011, OR = 4.3). LAM avulsion rate was 9.6% in NVD versus 34.2% in VD (p = 0.001, OR 3.99), while levator hiatus area at rest was 16.5 ± 3.2 versus 18.2 ± 3.9 (p = 0.016).Conclusions: Vacuum assisted deliveries present a higher rate of LAM avulsion, as well as a greater increase in levator hiatal area than in NVD.