Comparison of resistive index versus pulsatility index in assessing the benign etiology of adnexal masses.

Retrospective analysis of pelvic sonograms with colorguided spectral Doppler evaluation of 189 adnexal masses yielded four malignancies, 20 benign neoplasms, 32 cysts, and 14 endometriomas. Fifty-eight masses were presumed benign on additional imaging. Pulsatility index (PI) < 1.0 was seen in 70% neoplasms, 63% benign cysts and 50% endometriomas. Thirteen percent of benign cysts and no neoplasms had resistive index (RI) < 0.4. Fifty percent malignancies had PI < 1.0. None had RI < 0.4. Both thresholds lack sufficient sensitivity and specificity for distinguishing benign and malignant lesions.