Sonographic evaluation of adnexal masses is subject to a variety of potential pitfalls that can lead to diagnostic overcalls and undercalls. Familiarity with the pitfalls associated with sonographic findings related to normal ovarian physiology, hemorrhagic ovarian cysts, endometriomas, cystic teratomas, extraovarian cystic masses, and exophytic uterine masses helps the imager avoid subjecting patients to unnecessary anxiety and testing, unnecessary or needlessly aggressive surgical evaluation, and incorrect diagnoses.