Performance of International Ovarian Tumor Analysis Simple Rules and Ovarian-Adnexal Reporting and Data System for classifying benign and malignant pediatric adnexal lesions using ultrasound.

BACKGROUND: The International Ovarian Tumor Analysis Simple Rules (IOTA-SR) and Ovarian-Adnexal Reporting and Data System (O-RADS) are established tools for adult adnexal lesions but lack pediatric validation. OBJECTIVE: To assess the diagnostic performance of IOTA-SR and O-RADS for malignant adnexal lesions in children. MATERIALS AND METHODS: In this retrospective study, pediatric patients with confirmed adnexal lesions at a tertiary referral hospital between January 2015 and January 2025 were included. All lesions were classified according to O-RADS and IOTA-SR, with expert review for inconclusive cases. Diagnostic performance, including sensitivity, specificity, predictive values, accuracy, and area under the receiver operating characteristic curve (AUC), was evaluated and compared between lesion-size subgroups (≥10 cm vs. <10 cm). RESULTS: A total of 431 adnexal lesions (mean diameter 7.8 cm) from 431 pediatric patients (one lesion per patient, mean age 15.0 years) were analyzed. The estimated malignancy risk in the highest-risk category was significantly greater in lesions ≥10 cm than in smaller lesions for both systems (O-RADS 5: 95.8% vs. 63.6%, P=0.026; IOTA-SR malignant classification: 95.7% vs. 66.7%, P=0.038). Overall and for lesions <10 cm, O-RADS and IOTA-SR demonstrated high and comparable diagnostic performance (overall AUC: 0.910 vs. 0.908, P=0.920; <10 cm AUC: 0.906 vs. 0.880, P=0.464). However, for lesions ≥10 cm, the AUC of O-RADS was significantly lower than that of IOTA-SR (0.835 vs. 0.921, P=0.023). CONCLUSIONS: Both O-RADS and IOTA-SR show acceptable diagnostic performance for pediatric adnexal lesions. IOTA-SR outperforms O-RADS in stratifying large lesions (≥10 cm) and may be preferable in such cases, while either system can be used effectively for smaller lesions.