Use of risk of malignancy index to indicate frozen section analysis in the surgical care of women with ovarian tumors

Abstract Objective To evaluate the importance of the risk of malignancy index (RMI) in the decision to perform frozen section analysis among women with ovarian tumors. Methods A retrospective study was conducted in 11 centers in the Netherlands. Women who underwent surgical treatment of an ovarian mass with unknown histology between January 2005 and September 2009 were included. The RMI was calculated retrospectively. Frozen section analysis and RMI values were assessed for patients with benign, borderline, and malignant ovarian tumors on final histopathology. Results Overall, 670 women were included. Frozen sections were performed in 323 (48.2%) patients, of whom 206 (63.8%) were diagnosed with benign ovarian tumors, 55 (17.0%) with borderline tumors, and 62 (19.2%) with malignant tumors. Overall, 109 (16.3%) women had an RMI below 20, 106 (97.2%) of whom had benign histology results. Among 235 patients with an RMI over 100, 3 (1.3%) postmenopausal women had malignancies that were missed because frozen sections were not performed. Conclusion Women with an RMI below 20 have a low risk of malignancy and therefore do not require frozen section analysis. Postmenopausal women with an RMI greater than 100 should be referred to centers where frozen sections can be performed, and proper facilities and expertise are available to perform staging procedures if necessary.