Evaluation of labor-related pelvic floor changes 3 months after delivery: a 3D transperineal ultrasound study

Abstract

Introduction and hypothesis: The levator hiatus and puborectalis muscle play a critical role in supporting the pelvic organs. Vaginal birth is known to be the main etiological factor for development of levator defects. The aim of this study was to define and evaluate changes in the levator ani immediately and at 3 months after delivery with 3D transperineal ultrasonography.

Methods: Of 92 eligible primiparous women who delivered vaginally, 84 were examined within 36 h of delivery (early evaluation) and 3 months after delivery (late evaluation) with 3D transperineal ultrasonography. 3D volumes were evaluated in the supine position after voiding. Levator biometry, levator defect and loss of tenting were determined in the axial plane.

Results: The levator defect rate was significantly higher at the early evaluation (71.4 %) than at the late evaluation (39.6 %; p < 0.0001). Levator thickness and transverse hiatal diameters on resting and during maximal Valsalva maneuver were greater at the late evaluation than at the early evaluation. Anteroposterior hiatal dimension, hiatal area on resting and maximal during the Valsalva maneuver were greater at the early evaluation than at the late evaluation. Head circumference and the length of the first stage of labor were associated with levator defects.

Conclusions: Changes in the levator hiatus could be transitional or persist over time. There were significant changes in levator hiatus measurements, levator thickness, levator defect incidence and loss of tenting rate between early postpartum and late postpartum. The head circumference of the fetus and the length of the first stage of labor are the shared and consistent factors that can be associated with pelvic floor trauma.

Keywords: Levator ani muscle; Levator hiatus; Pelvic floor.