Timing of Caesarean Section and its impact on levator ani avulsion at the first subsequent vaginal birth: a pilot study

Abstract

Objective:. The aim of this multicentric observational study was to explore the impact of timing of cesarean section on levator ani avulsion at the first subsequent vaginal birth.

Methods: All women after a term vaginal birth after cesarean section (VBAC) for their second delivery at the Departments of Gynecology and Obstetrics, Faculty of Medicine in Pilsen and the 1st Faculty of Medicine , Prague,  Charles University, Czech Republic between 2012 and 2016 were identified. Hospital database and surgical notes were used to collect basic characteristics of the patients including the indication and course of their previous delivery. These women were divided into two groups according to indication of prior Cesarean Section (SC) in the previous delivery to women with elective SC and acute SC. All participants were invited for a 4D pelvic floor ultrasound to assess levator trauma. Levator avulsion and the levator hiatus area were assessed off-line from the stored pelvic floor volumes.  Data were statistically assessed. 

Results: A total of 356 women had a VBAC for their second delivery during the study period. Of these, 152 (42,7%) attended the ultrasound examination and full data were available for 141 women for statistical analyses. These were further divided into 80 women after acute SC and 61 women after elective SC. The levator avulsion rate was higher in  elective SC subgroup, but the difference is not significant (26,3% vs. 41,0%, p= 0.0645). No statistically differencies in urogenital hiatus enlargement and ballooning were observed.

Conclusions: VBAC is associated with a significantly higher rate of levator ani avulsion compared to the first vaginal birth in nulliparous women. However, it seems that risk of levator ani avulsion doesn´t depend on the timing of Ceasarean Section in previous labor. More studies are needed to confirm the results of this pilot study.

Keywords: 4D transperineal ultrasound, levator ani muscle, avulsion injury, VBAC, pelvic floor