Comparative Diagnostic Performance of IOTA Simple Rules, O-RADS US, and Subjective Assessment in Differentiating Benign from Malignant Adnexal Masses.

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.