To assess the ability of risk of malignancy index (RMI) based on ultrasound findings, serum levels of CA 125, and menopausal status to discriminate between benign and malignant ovarian masses for preoperative screening.

A retrospective study was conducted of 255 women with ovarian masses admitted for operation at the Department of Obstetrics and Gynecology, Hanyang University Hospital between 1999 and 2003. The sensitivity and specificity of serum levels of CA 125, ultrasound findings, and menopausal status were calculated both separately and combined into a RMI to diagnose malignancy.

There were significant preoperative differences of ultrasound findings, serum CA 125 level, serum CA 19-9 level, platelet count and menopausal status between benign and malignant ovarian masses (P<0.05). Using a cut-off value of 100 to indicate malignancy, the RMI gave a sensitivity of 81.7%, specificity of 81.9%. The RMI was more accurate in predicting malignancy than each one of its components measured individually.

The RMI is able to correctly discriminate between malignant and benign ovarian masses. This preoperative evaluation of women with ovarian masses is anticipated to help plan their management.