OP06.03: Preoperative sonographic evaluation of adnexal masses using the new Ovarian‐Adnexal Reporting and Data System

In the management of ovarian masses, preoperative sonographic evaluation of malignancy is important to plan the surgical approach correctly and to improve patients' outcomes. The Risk of Malignancy Index (RMI) has been the gold standard in preoperative assessment for preoperative triage. Ovarian-Adnexal Reporting and Data System (O-RADS) score was established to estimate the risk of malignancy and suggest further management steps. We aimed to compare the accuracy of RMI versus O-RADS in the prediction of malignancy of ovarian masses. This was a retrospective analysis of prospectively collected data. Patients were included if they had a preoperative ultrasound in our unit and a pathological report was available as reference. RMI and O-RADS based on the International Ovarian Tumor Analysis (IOTA) ADNEX model were assessed. Performance was assessed using receiver- operating characteristic (ROC) curves. 453 cases were included between 2018 and 2023. 89 (19.8%) were diagnosed with a malignant tumour, 21 (4.6%) had borderline tumours and 343 (75.8%) had benign lesions. The area under the ROC curve (AUC) for prediction of malignancy was 0.949 (95% CI, 0.923-0.975) for O-RADS and 0.905 (95% CI, 0.866-0.944) for RMI with a cut-off of >200. For O-RADS, sensitivity for the prediction of malignancy was 95.5%, specificity 79.2%, and positive predictive value (PPV) and negative predictive value (NPV) were 59.9% and 98.2%, respectively. For RMI with a cut-off of >200 sensitivity was 69.7%, specificity 93.4%, PPV and NPV were 79.2% and 89.5%, respectively. The AUC for prediction of borderline tumours was 0.898 (95% CI, 0.820-0.975) for the O-RADS and 0.721 (95% CI, 0.601-0.841) for RMI. The O-RADS score based on ADNEX model had a better performance for preoperative assessment of adnexal masses compared to RMI. For the detection of borderline tumours the advantages of O-RADS compared to RMI are most prominent. O-RADS should be implemented into routine assessment of adnexal masses.