Abstract

Objectives: To compare the diagnostic performance of International Ovarian Tumor Analysis (IOTA) Simple Rules, Ovarian-Adnexal Reporting and Data System for Ultrasound (O-RADS US), and Subjective Assessment in differentiating benign from malignant adnexal masses.

Methods: This prospective study included 249 women evaluated between May 2021 and June 2025 at a tertiary oncology center. Participants underwent standardized transvaginal ultrasound classified according to IOTA Simple Rules, O-RADS US, and Subjective Assessment by examiners blinded to biomarker and imaging results. Most examinations (78%) were performed by a level 2 radiologist, 11% by a level 3 gynecologist, and 11% by level 2 gynecologist sonographers. Final diagnosis was established by histopathology (n = 243) or ≥2 years of follow-up (n = 6). Diagnostic performance was assessed using sensitivity, specificity, predictive values, accuracy, likelihood ratios, and diagnostic odds ratios (DOR), with pairwise comparisons performed by McNemar's test.

Results: Malignant lesions were associated with older age, larger size, complex morphology, ascites, and higher CA125 (p < .05). O-RADS US achieved the highest sensitivity (98.2%) and negative predictive value (95.9%) but the lowest specificity (33.8%). Subjective Assessment had the highest specificity (75.2%) and accuracy (79.6%) but lower sensitivity (85.6%). Simple Rules demonstrated balanced performance (sensitivity 94.6%, specificity 56.8%). DORs were comparable (17.9-27.6). In terms of accuracy, Simple Rules and Subjective Assessment outperformed O-RADS US, while no statistically significant difference was observed between Simple Rules and Subjective Assessment. Inter-method agreement was highest between Simple Rules and Subjective Assessment (κ = 0.69), followed by Simple Rules and O-RADS US (κ = 0.62), and O-RADS US and Subjective Assessment (κ = 0.41).

Conclusion: O-RADS US maximized sensitivity for malignancy detection, Simple Rules provided balanced accuracy, and Subjective Assessment offered superior specificity. Their complementary use may optimize adnexal mass characterization across clinical settings.