Ultrasound Obstet Gynecol. 2021 Mar 16. doi: 10.1002/uog.23629. Online ahead of print.
ABSTRACT
OBJECTIVE: The aim of the study was to explore the risk of levator ani avulsion and levator hiatus enlargement following vaginal birth after cesarean section (VBAC) in comparison to primiparous women after their first vaginal delivery.
METHODS: In this multicenter observational cohort study we identified all women who had a term 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. Women having a repeat VBAC, preterm birth or stillbirth were excluded from the study. As a control group, we enrolled a cohort of primiparous women who had their first vaginal birth during the studied period. To increase our control sample we also invited all primiparous women who delivered vaginally between May and June 2019 . All participants were invited for a 4D pelvic floor ultrasound to assess levator trauma. Levator avulsion and the levator hiatus area at rest and on maximal Valsalva were assessed off-line from the stored pelvic floor volumes during contraction and Valsalva. The laterality of the avulsion was additionally noted. The cohorts were then compared using Chi-square test and Wilcoxon two-sample test according to the distribution of normality, p-value <0.05 was considered statistically significant. Multivariate regression controlling for age and BMI was additionally performed.
RESULTS: A total of 301 women had a VBAC for their second delivery during the studied period. Of these, 152 (50.5%) attended the ultrasound examination and full data were available for 141 women for statistical analyses. The control group comprised 113 primiparous women. A significant difference between VBAC and control group in age (32.7 vs. 30.1 years, p < 0.05), BMI (28.4 vs 27.4, p < 0.05), durations of the first (293.1 vs 346.9 min, p < 0.05) and the second (27.6 vs 35.5 min, p < 0.05) stages of labor at time of the index birth was observed. The levator avulsion rate was significantly higher in the VBAC compared to the control group (32.6 vs 18.6 %, p = 0.01). The difference was observed dominantly in unilateral avulsions and remained significant after controlling for age and BMI (adjusted OR 2.061; 95% CI:1.103 – 3.852). There were no statistically significant differences in the size of levator hiatus at rest (12.0 vs. 12.6 cm2 , p = 0.28) or Valsalva (18.6 vs. 18.7 cm2 , p = 0.55). The incidence of levator ballooning was comparable in VBAC and Controls (17.7 % and 18.6 %, p = 0.9).
CONCLUSIONS: VBAC is associated with a significantly higher rate of levator ani avulsion compared to the first vaginal birth in nulliparous women. The difference was significant even after controlling for age and BMI. This article is protected by copyright. All rights reserved.
PMID:33724564 | DOI:10.1002/uog.23629
