To compare the diagnostic performance of the Ovarian-Adnexal Reporting and Data System (O-RADS), the risk of malignancy index 4 (RMI4), the International Ovarian of Tumor Analysis logistic regression model 2 (IOTA LR2) and IOTA simple rule (IOTA SR) in predicting the malignancy of adnexal masses (AMs).Methods: This was a retrospective study of 575 women with AMs between 2017 and 2020. All clinical messages, ultrasound images, and pathological findings were collected. Two senior doctors (Group I) and two junior doctors (Group II) used the four systems to classify AMs. The postoperative pathological diagnosis was used as the gold standard to evaluate the diagnostic efficiency. Receiver operating characteristic curve was used to test the diagnostic performance.The interrater agreement between the two groups was tested by the kappa value.Results: Of all 592 AMs, 447 (75.5%) tumors were benign, 123 (20.8%) were malignant, and 22 (3.7%) were borderline. The intergroup consistency test yielded kappa values of 0.71, 0.92, 0.68 and 0.77 for the O-RADS, RMI4, IOTA LR2 and IOTA SR, respectively. To predict malignant lesions, the areas under the curve of the O-RADS, RMI4, IOTA LR2 and IOTA SR systems were 0.90, 0.89, 0.90 and 0.86 for Group I and 0.89, 0.87, 0.88 and 0.84 for Group II, respectively. The O-RADS had the highest sensitivity of 91.0% in Group I and 84.8% in Group II. Conclusion:The four diagnostic systems could compensate for junior doctors' inexperience in predicting malignant adnexal lesions. The O-RADS performed best with the highest sensitivity.

Objectives-To describe the ultrasonographic signs of ovarian collision tumors and evaluate the malignancy risk using the O-RADS system.Methods-This was a retrospective analysis of 25 ovarian collision tumors from 8739 patients between May 2010 and January 2020. All clinical characteristics, ultrasound images, and histological findings were collected and analyzed. Using the O-RADS lexicon descriptors, the O-RADS score was determined by two senior doctors. Lesions with O-RADS scores of 1 to 3 were classified as benign tumors, and lesions with O-RADS scores of 4 to 5 were classified as malignant tumors.Results-The mean age of the 25 patients was 30.4 years. Histological findings showed that all tumors were a combination of mature cystic teratomas and cystadenomas/cystadenocarcinomas. There were 11 benign tumors of O-RADS 2 or 3, including 3 uniocular cysts, 3 dermoid cysts, and 5 dermoid cysts with an anechoic fluid cavity. There were 12 benign tumors of O-RADS 4, including 3 uniocular-multilocular cysts with solid components, 2 multilocular cysts with irregular walls, and 8 multilocular cysts with dermoid sacs. One borderline tumor of O-RADS 4 was a multilocular cyst with irregular septation. One malignant tumor of O-RADS 5 was a multilocular cystic tumor with solid components and ascites.Conclusions-The most common ovarian collision tumor was the coexistence of a mature cystic teratoma and a cystadenoma. The O-RADS system was able to sensitively detect malignant tumors in this series. A typical dermoid cyst with an anechoic cavity or a multilocular cyst with a dermoid sac may signify a benign collision tumor.

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