Distinguishing benign from malignant adnexal masses is critical for correct surgical management, defined as ovarian conservation for benign masses and oophorectomy for malignancies.1,2 Pre-operative risk stratification at our institution incorporates a threshold of >8 cm and complex/solid on ultrasound to suggest malignancy.1 Since implementing this criteria in an algorithm, correct identification of malignancies has increased, while correct identification of benign masses has decreased. We hypothesize that applying more refined imaging criteria may improve specificity. A new algorithm, The Decision Tree System (DTS), which uses ultrasound characteristics almost exclusively, has a preoperative sensitivity and specificity for malignancy of 92% and 96%, respectively.3 The purpose of this study is to 1) investigate if the DTS has a similar performance for pre-operative risk stratification in another population, and 2) compare the DTS with our current management of adnexal masses.