Sonographic knowledge of occiput position to decrease failed operative vaginal delivery: a systematic review and meta-analysis of randomized controlled trials

Objective: This study aimed to assess the efficacy of sonographic assessment of fetal occiput position before operative vaginal delivery to decrease the number of failed operative vaginal deliveries. Data Sources: The search was conducted in MEDLINE, Embase, Web of Science, Scopus, ClinicalTrial.gov, Ovid, and Cochrane Library as electronic databases from the inception of each database to April 2021. No restrictions for language or geographic location were applied. Study Eligibility Criteria: Selection criteria included randomized controlled trails of pregnant women randomized to either sonographic or clinical digital diagnosis of fetal occiput position during the second stage of labor before operative vaginal delivery. Methods: The primary outcome was failed operative vaginal delivery, defined as a failed fetal operative vaginal delivery (vacuum or forceps) extraction requiring a cesarean delivery or forceps after failed vacuum. The summary measures were reported as relative risks or as mean differences with 95% confidence intervals using the random effects model of DerSimonian and Laird. An I2 (Higgins I2) >0% was used to identify heterogeneity. Results: A total of 4 randomized controlled trials including 1007 women with singleton, term, cephalic fetuses randomized to either the sonographic (n=484) or clinical digital (n=523) diagnosis of occiput position during the second stage of labor before operative vaginal delivery were included. Before operative vaginal delivery, fetal occiput position was diagnosed as anterior in 63.5% of the sonographic diagnosis group vs 69.5% in the clinical digital diagnosis group (P=.04). There was no significant difference in the rate of failed operative vaginal deliveries between the sonographic and clinical diagnosis of occiput position groups (9.9% vs 8.2%; relative risk, 1.14; 95% confidence interval, 0.77–1.68). Women randomized to sonographic diagnosis of occiput position had a significantly lower rate of occiput position discordance between the evaluation before operative vaginal delivery and the at birth evaluation when compared with those randomized to the clinical diagnosis group (2.3% vs 17.7%; relative risk, 0.16; 95% confidence interval, 0.04–0.74; P=.02). There were no significant differences in any of the other secondary obstetrical and perinatal outcomes assessed. Conclusion: Sonographic knowledge of occiput position before operative vaginal delivery does not seem to have an effect on the incidence of failed operative vaginal deliveries despite better sonographic accuracy in the occiput position diagnosis when compared with clinical assessment. Future studies should evaluate how a more accurate sonographic diagnosis of occiput position or other parameters can lead to a safer and more effective operative vaginal delivery technique.