Adnexal masses in pregnancy.

Adnexal masses are often seen in the gravid patient. With current advances in technology, an increased number of adnexal masses are incidentally discovered on antenatal screening ultrasonography examinations. Sonography is the first-line imaging modality for any adnexal mass. However, further evaluation with magnetic resonance imaging (MRI) may be critical for diagnosis. For example, MRI can determine whether a mass contains fat, which can be useful in the diagnosis of a teratoma. Characteristic features of nonneoplastic and neoplastic ovarian lesions seen on sonography and MRI will be discussed. Radiologic features that help distinguish benign from malignant neoplasms will be described. Additional lesions specific to the gravid state must be considered in the differential diagnosis when appropriate, such as hyperstimulated ovaries, hyperreactio luteinalis, theca lutein cyst, and luteomas.