Comparison of Ovarian-Adnexal Reporting and Data System (O-RADS) Ultrasound and International Ovarian Tumor Analysis (IOTA) Simple Rules in Characterizing Benign and Malignant Ovarian Lesions: A Retrospective Study

Objective The objective of this study is to compare the diagnostic accuracy of the Ovarian-Adnexal Reporting and Data System (O-RADS) and the International Ovarian Tumor Analysis (IOTA) Simple Rules in distinguishing benign from malignant ovarian masses, using histopathology as the reference standard. Methods This study was a retrospective observational investigation carried out in a tertiary care facility and included women with ovarian masses who underwent ultrasound evaluation between January 2023 and December 2025, followed by surgical excision with histopathological confirmation. Ultrasound images were retrospectively reviewed by two radiologists who were blinded to the final histopathological diagnosis. In cases of disagreement, a consensus decision was reached. The lesions were classified according to O-RADS and IOTA Simple Rules based on the recorded imaging features. O-RADS categories 4-5 were considered positive for malignancy. Inconclusive IOTA cases were excluded from performance analysis. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated. Multivariate logistic regression was performed to identify independent predictors of malignancy. Results Histopathology confirmed 24 (30%) malignant and 56 (70%) benign lesions. O-RADS demonstrated 91.7% sensitivity, 82.1% specificity, 68.8% PPV, 95.8% NPV, and 85.0% overall accuracy. IOTA yielded 12 (15%) inconclusive cases. After exclusion, IOTA showed 91.7% sensitivity, 95.5% specificity, 91.7% PPV, 95.5% NPV, and 94.1% accuracy. In a secondary analysis considering inconclusive cases as malignant, IOTA demonstrated 92.3% sensitivity, 78.6% specificity, 66.7% PPV, 95.7% NPV, and 85% accuracy. Solid components (OR 8.4), very strong vascularity (OR 7.5), and ascites (OR 6.9) were independent predictors of malignancy. Conclusions Both O-RADS and IOTA Simple Rules demonstrate high diagnostic performance in distinguishing benign from malignant adnexal lesions. O-RADS offers greater sensitivity and applicability across all lesions, supporting its role in clinical triage, while IOTA provides higher specificity in classifiable cases but is limited by inconclusive results. When such cases are included, diagnostic performance becomes more comparable. O-RADS, therefore, represents a more consistent and clinically applicable framework.