Abstracts of the 36th World Congress on Ultrasound in Obstetrics and Gynecology, 4-7 September 2026, London, UK

Objectives: This preliminary analysis of an ongoing prospective cohort study aims to validate novel threshold-based and decision-tree (DT) based ultrasound (US) and surgical endometriosis staging systems developed on a retrospective cohort proposed by Mak et al. 2023 to predict AAGL surgical complexity level.Methods: This prospective cohort study conducted across three sites in Sydney, Australia commenced 30th November 2023 and is ongoing.A total of 165 participants presenting with clinical symptoms suggestive of endometriosis that elected for surgical management were recruited.Particpants undergo transvaginal ultrasound (TVS) for deep endometriosis (DE) reported per IDEA consensus statement.Operative findings were documented contemporaneously via cloud based database.Corresponding ultrasound and surgical stages are calculated within the database with AAGL surgical complexity level A-D.Three and four-stage models were assessed for both ultrasound and surgery.Surgical complexity levels of B and C were combined for the three stage model analysis.Results: Of 165 particpants, 29 were excluded due to incomplete data, leaving 134 participants for analysis.Mean age was 33.3 years, BMI 27.3.Agreement with AAGL surgical complexity was highest for the 4-stage and 3-stage surgical threshold based systems with weighted kappa (WK) 0.76 and 0.71 respectively.The 3 and 4-stage surgical DT systems had WK 0.71 and 0.69.Preoperative models of 3-stage DT, 4-stage threshold, 3-stage threshold and 4-stage DT sytems had WK of 0.63, 0.60, 0.59 and 0.58 respectively.Within this cohort the reference standard of agreement between AAGL surgical stage and surgical complexity level had WK of 0.63.Conclusions: The best performing system was the 4-stage threshold based surgical staging with highest agreement with AAGL surgical complexity.Within this cohort the reference standard of AAGL surgical stage was out-performed by all proposed surgical staging systems and comparable with the ultrasound based 3-stage decision tree system.