EP19.06: Standardisation and reproducibility of transperineal measurements of breech progression angle for evaluating fetal breech descent

To evaluate the reproducibility of measurements of breech progression angle (BPA) by transperineal ultrasound (US) before and after its standardization by applying an image-based score. Twenty three-dimensional (3D) volumes of transperineal US corresponding to women at 36-40 weeks with a single fetus in breech position were provided to eight operators from four maternity units in Spain and Italy. All operators measured the BPA using 3D US volume processing software, and interobserver reproducibility was assessed by the intraclass correlation coefficient (ICC). After an online live review of all measurements by all operators, an image-based score for BPA measurement was jointly designed. BPA was measured again by all operators in all volumes, and reproducibility was re-assessed. Two of the twenty volumes were discarded due to insufficient quality for BPA measurement. Eighteen volumes were analysed by the eight operators, achieving moderate reproducibility (ICC: 0.696, 95% confidence interval (CI): 0.479 to 0.857). A score was developed to include a series of landmarks for appropriate assessment of BPA (see table 1). Subsequently, reassessment of the same eighteen volumes applying this new score improved reproducibility (ICC: 0.813, 95% CI: 0.660 to 0.916). Measurement of BPA is feasible and reproducible when using a standardised image-based score. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.