This is a large multicenter trial designed to determine the efficacy of second stage diagnostic testing when the primary diagnostic test has provided an uncertain diagnosis of a benign or malignant adnexal mass. Women with adnexal masses were evaluated using ultrasonography. Clinical and ultrasonographic data were employed to determine the risk of malignancy using 11 statistical models and their performance was evaluated based on histologic findings at surgery. Overall, the ultrasound examiner's subjective evaluation had the highest area under the curve and specificity, with respect to diagnostic performance. Of the mathematical models evaluated, LR1 performed the best, with an area under the curve of 0.95, a sensitivity of 92% and a specificity of 84%. The accuracy of subjective evaluation did not improve with the addition of any second stage test. If the LR1 model was used as the primary diagnostic test, the addition of subjective evaluation as a secondary test was found to be beneficial.