Ovarian Adnexal Reporting Data System (O-RADS) for Classifying Adnexal Masses: A Systematic Review and Meta-Analysis

Abstract

In this systematic review and meta-analysis, we aimed to assess the pooled diagnostic performance of the so-called Ovarian Adnexal Report Data System (O-RADS) for classifying adnexal masses using transvaginal ultrasound, a classification system that was introduced in 2020. We performed a search for studies reporting the use of the O-RADS system for classifying adnexal masses from January 2020 to April 2022 in several databases (Medline (PubMed), Google Scholar, Scopus, Cochrane, and Web of Science). We selected prospective and retrospective cohort studies using the O-RADS system for classifying adnexal masses with histologic diagnosis or conservative management demonstrating spontaneous resolution or persistence in cases of benign appearing masses after follow-up scan as the reference standard. We excluded studies not related to the topic under review, studies not addressing O-RADS classification, studies addressing MRI O-RADS classification, letters to the editor, commentaries, narrative reviews, consensus documents, and studies where data were not available for constructing a 2 × 2 table. The pooled sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio (DOR) were calculated. The quality of the studies was evaluated using QUADAS-2. A total of 502 citations were identified. Ultimately, 11 studies comprising 4634 masses were included. The mean prevalence of ovarian malignancy was 32%. The risk of bias was high in eight studies for the "patient selection" domain. The risk of bias was low for the "index test" and "reference test" domains for all studies. Overall, the pooled estimated sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and DOR of the O-RADS system for classifying adnexal masses were 97% (95% confidence interval (CI) = 94%-98%), 77% (95% CI = 68%-84%), 4.2 (95% CI = 2.9-6.0), 0.04 (95% CI = 0.03-0.07), and 96 (95% CI = 50-185), respectively. Heterogeneity was moderate for sensitivity and high for specificity. In conclusion, the O-RADS system has good sensitivity and moderate specificity for classifying adnexal masses.

Keywords: O-RADS; benign neoplasms; malignancy; meta-analysis; ovarian cancer diagnosis; ovarian neoplasms; transvaginal ultrasound.

Figure 1

Flowchart showing study selection process, indicating the titles found in each database, as well as the exclusion process and the final number of studies ultimately included in the meta-analysis.

Figure 2

This figure shows the quality assessment (risk of bias and concerns about applicability) for all studies included in the meta-analysis.

Figure 3

Forest plot for sensitivity and specificity for all studies using the O-RADS reporting system. Pooled sensitivity and specificity are also shown, as well as the heterogeneity found.

Figure 4

Summary ROC curve for O-RADS reporting system showing the sensitivity and specificity for each study and pooled estimation. The dashed line around the summary point estimate (red diamond) represents the 95% confidence region. The dotted line showing the 95% prediction contour corresponds to the predicted performance taking into account all individual studies.

Figure 5

Fagan nomogram for O-RADS reporting system. It can be observed how the test changes the pre-test probability depending on a positive or negative result.