Diagnostic accuracy and appropriate cut off value of risk of malignancy index in preoperative descrimination between malignant and benign ovarian tumors in jimma medical center, jimma town, oromia region, south west Ethiopia, 2020

Abstract

Background: Risk of malignancy index is scoring system which was introduced to differentiate between benign and malignant ovarian tumor. It incorporates CA-125, ultrasound score and menopausal status for prediction of ovarian malignancies in preoperative period. There is no universal screening method to discriminate between benign and malignant adnexal masses yet. So, this study was conducted to determine the diagnostic accuracy of RMI and determine best cut off value for RMI. Methods: Prospective cross-sectional study was carried out among women with ovarian mass admitted to Gynecology ward and operated from September 1, 2019 to June 30, 2020.Data analysis was carried out using SPSS version 26. CA-125 level, menopausal status and ultrasound score were used to calculate RMI. Finally, RMI score was compared to histopathology result used as gold standard. Results: 99 patients were enrolled in this study. Prevalence of benign ovarian tumors were 61.6% (61/99) and that of malignant ovarian tumors were 38.4% (38/99). The mean age for benign tumors was 30±9yrs and the mean age for malignant tumors was 50.6±10.8yrs. Among benign tumors, serous cystadenoma was the most common (36%), followed by dermoid cyst (32.9%), mucinous cyst adenoma (14.8%). The most common malignant ovarian tumor was serous cyst adenocarcinoma (63.2%), followed by mucinous cystadenocarcinoma (23.8%) and dysgerminoma (5.3%). Overall, using RMI score cut off value 220 has good sensitivity (84.2%), specificity (77%), PPV (69.5%), NPV (88.7%) and diagnostic accuracy (79.8%) for discriminating between benign and malignant ovarian tumors. Conclusion: From this study there were high proportion of women with RMI>=220 in malignant ovarian tumor group. The study shows that there is significant role of RMI in prediction of ovarian malignancy thus helping in deciding which patients need referral to a center where gynecologic oncologists are available. It is good practice to use it in developing countries including our country because of its simplicity, safety and applicability in initial evaluations of patients with adnexal mass.