To compare the value of different models in the diagnosis of the adnexal masses.

We retrospectively collected patients with adnexal masses detected by transvaginal or transrectal ultrasound at the department of ultrasound of First Center in Chinese PLA General Hospital from October 2017 to September 2021. Simple rules (SR), Logistic regression model 2 (LR2), and ovarian-adnexal reporting and data system (O-RADS) were used to evaluate the ultrasound features of the cases, and the pathological results were used as the reference standards. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic efficacy of the three models. The area under the ROC curve (AUC) values were compared by the DeLong method. The paired chi-square test was used to compare sensitivities and specificities. The chi-square test and Fisher's exact test were used to compare positive predictive values (PPV) and negative predictive values (NPV).

Among the 151 masses, 106 (70.20%) were benign and 45 (29.80%) were malignant according to the pathological results. The AUC values of SR, LR2, and O-RADS were 0.901 (0.842-0.944), 0.940 (0.890-0.972), and 0.926 (0.872-0.963), respectively. The AUC of SR was significantly lower than that of LR2 (P=0.034), but there was no significant difference between SR and O-RADS, or between LR2 and O-RADS (P＞0.05 for both). The sensitivity, specificity, PPV, and NPV of SR were 100%, 80.19%, 68.18%, and 100%, respectively. The cutoff for LR2 was＞0.125, and the sensitivity, specificity, PPV and NPV were 95.56%, 85.85%, 74.14%, and 97.85%, respectively. The cutoff for O-RADS was＞3, and the sensitivity, specificity, PPV, and NPV were 100%, 78.30%, 66.18%, and 100%, respectively. There was no significant difference in sensitivity, PPV, or NPV between O-RADS, LR, and SR. No significant difference was detected in specificity between SR and LR2, SR and O-RADS (P＞0.05). The specificity of O-RADS was significantly lower than that of LR2 (P=0.021). There were three adnexal masses that showed acoustic shadows among masses misdiagnosed by O-RADS, all of which were diagnosed correctly by SR. All of the 26 masses that presented with acoustic shadows in our study were pathologically confirmed to be benign. There were 12 adnexal masses misdiagnosed by all the three models, three of which were diagnosed to be benign masses by contrast enhanced ultrasound and confirmed by pathology. Another six patients (4 patients with inflammation and 2 patients with rupture of endometriosis masses) showed typical clinical symptoms and laboratory examination results.

SR, LR, and O-RADS have similar sensitivity, but the specificity of O-RADS is the lowest. Using acoustic shadows of adnexal masses as one of the principles of O-RADS to recognize benign masses may improve the accuracy of that model. Contrast enhanced ultrasound, clinical symptoms, and laboratory examination can help to differentiate benign and malignant adnexal masses.