The fetal occiput-spine angle measurement during first stage of labor as a predictor for vaginal delivery, a systematic review and meta-analysis

Objectives To evaluate the diagnostic utility of the fetal occiput-spine angle (OSA) measured by transabdominal ultrasonography in predicting successful vaginal delivery (VD) during the first stage of labor. Methods A systematic search of MEDLINE, Scopus, EMBASE databases, and Google Scholar was conducted from January 15, 2025, to February 1, 2025, following the Preferred Reporting Items for Systematic Reviews and Meta-analyses for diagnostic test accuracy guidelines. Two independent reviewers selected studies according to inclusion criteria, extracted data, and assessed risk of bias assessed by the Quality Assessment of Diagnostic Accuracy Studies-2. Results Six studies with 1,129 participants were included. The pooled sensitivity and specificity of OSA for predicting VD were 86 % (95 % confidence interval (CI): 73–93 %) and 80 % (95 % CI: 37–97 %), respectively. The DOR was 23.71 (95 % CI: 2.5–223.36 %). The mean OSA of women with successful VD was 10.44° wider than that of women who underwent cesarean delivery, although not significant (p=0.16). High heterogeneity (I 2 >88.2 %) was observed. The risk of bias was low across most domains. Conclusions The fetal OSA demonstrated moderate diagnostic value in predicting successful VD. Furthermore, additional high-quality, large-scale studies with standardized cut-offs are necessary to verify its clinical utility.