Transperineal ultrasonography angle of progression measurement as a predictor of successful labor in pregnancy with induction of labor: a systematic review and meta-analysis

Abstract

Introduction: Induction of labor (IOL) is a common obstretic procedure that carries maternal and fetal risks. The sonographic angle of progression (AOP), which is the angle between the pubic symphysis and the inferior portion of the fetal skull, has been proposed as a predictor of successful vaginal delivery (VD) in IOL, but its diagnostic value remains unclear. Objective: To evaluate the diagnostic performance of AOP measured via transperineal ultrasonography (TPUS) in predicting successful IOL. Methods: A systematic search was conducted in EMBASE, MEDLINE, Scopus, and Google Scholar until October 2024, following PRISMA guidelines. Eligible cohort studies reported AOP values and IOL outcomes, with successful IOL defined as vaginal delviery (VD). Data were analyzed using a random-effects model, with heterogeneity assessed using I² statistics and publication bias evaluated with funnel plots and Egger’s test. Results: Eight studies including 1,883 women were analyzed. Women with successful VD had a wider AOP than those undergoing cesarean delivery (CD) by 7.48 degrees (95% CI: 0.27–14.69; p = 0.04) with high heterogeneity (I² = 97.59%). Sensitivity analysis reduced the mean difference to 4.64 degrees (95% CI: 2.61–6.68; p < 0.01), with lower heterogeneity (I² = 49.78%). The pooled odds ratio (OR) showed no significant association (OR: 0.96, 95% CI: 0.93–1.00; p = 0.04) with high heterogeneity (I² = 87.23%). Risk of bias was low based on the Newcastle-Ottawa scale, and publication bias analysis suggested asymmetry due to both bias and heterogeneity. Conclusion: Angle of progression was wider in IOL with successful VD; however, no significant association was found.