Background: Adnxal lesions represent an important health problem which leads to clinical workload and needs diagnostic imaging, surgery, and pathological evaluation. Classifying adnexal lesions is essential to allow decision making regarding the optimal management plan and to eliminate unnecessary patient anxiety.

Aim: To evaluate the diagnostic performance of US using the ORADS scoring system in distinguishing between benign and malignant adnexal masses

Methods: A prospective study including 77 paients with 94 adenxal masses. The lesions were cateogorized based on ORADS scorning system and were histopathologically evaluated . The diagnostic performances of ultrasound was measured by assessing receiver-operating characteristic curve, sensitivity , specificity, positive and negative predictive values

Results: of 77 paients 94 adnexal lesions were detected. The mean (S.D.) age of the patients was 33.96±14.38 years, and 64 of 77 (83.1%) were premenopausal. The overall frequency of malignant tumours was 18.1% (17 of 94 adnexal lesions).The optimal cutoff value for diagnosing malignancy was > O-RADS US 3 with a high sensitivity of 94.12%, specificity of 83.11%, and accuracy of 85.1% with 55.2% PPV and 98.5% NPV.

Conclusion: The O-RADS US classification system was an effective non-invasive diagnostic tool for adnexal masses with high reliability for gynaecologists and high sensitivity for suspicion of malignancy.