PRE-ECV Score: Validation of a Pre-Specified Tool for Predicting the Success of External Cephalic Version at Term—Proof of Concept

<b>Objectives:</b> We aimed to validate the predictive performance of the PRE-ECV Score, a pre-specified clinical tool, using logistic recalibration and bootstrap optimism correction to estimate the probability of successful external cephalic version (ECV) at term. <b>Methods:</b> The PRE-ECV Score was defined <i>a priori</i> based on a literature review and expert consensus, incorporating eight variables supported by level A or B scientific evidence (total score range 0-13). Validation of this pre-specified score was performed in a retrospective, single-center cohort of 100 consecutive ECV procedures between November 2023 and October 2025. Study conduct and reporting adhered to the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis (TRIPOD) statement. <b>Results:</b> The revised PRE-ECV Score demonstrated moderate discrimination (AUC = 0.76; 95% CI, 0.66-0.85). Calibration was moderate, with a bootstrap-corrected intercept of -3.02 (95% CI, -5.42 to -1.51) and a calibration slope of 0.70 (95% CI, 0.44-1.18). Observed ECV success rates increased across score strata, from 34.6% (0-4 points) to 79.4% (5-8 points) and 100% (≥9 points). <b>Conclusions:</b> The PRE-ECV Score demonstrated moderate discrimination and satisfactory calibration in this single-center validation. Given the small sample and model optimism, these results should be interpreted strictly as proof-of-concept.