External Validation of a Prediction Model for External Cephalic Version Success

Abstract

External cephalic version (ECV) success correlates with numerous maternal and pregnancy factors. A prior study developed an ECV success prediction model based on body mass index, parity, placental location, and fetal presentation. We performed external validation of this model using a retrospective cohort of ECV procedures from a separate institution between July 2016 and December 2021. Four hundred thirty-four ECV procedures were performed, with a 44.4% success rate (95% CI 39.8–49.2%), which was similar to the derivation cohort (40.6%, 95% CI 37.7–43.5%, P=.16). There were significant differences in patients and practices between cohorts, including the rate of neuraxial anesthesia (83.5% derivation cohort vs 10.4% our cohort, P<.001). The area under the receiver operating characteristic curve (AUROC) was 0.70 (95% CI 0.65–0.75), which was similar to that in the derivation cohort (AUROC 0.67, 95% CI 0.63–0.70). These results suggest the published ECV prediction model’s performance is generalizable outside the original study institution.