The imaging of adnexal masses represents a challenge and is very important to characterize the lesion with accuracy in the way to rule out malignancy.
Pelvic ultrasound is frequently the first imaging modality used when abnormalities are suspected of the ovaries or adnexa .
The goal of ultrasound evaluation in the pregnant patient with an adnexal mass is to identify those patients in whom conservative management is appropriate versus those who require more immediate interventions such as surgery .
Ovarian conditions unique to pregnancy include hyperstimulated ovaries and, less commonly, ovarian hyperstimulation syndrome, hyperrreactio luteinalis, theca lutein cysts, and luteoma of pregnancy. These conditions, with the exception of luteoma of pregnancy, are tipically bilateral, aiding in their recognition .
Theca lutein cysts typically appear as bilateral cystic masses with multiple septations. They are believed to be caused by an ovarian response to high levels of human chorionic gonadotropin. One would likely suspect theca lutein cysts by their typical appearance, although having an appropriate clinical history is helpful in making a more confident diagnosis .
Their sonographic appearance is that of bilateral enlarged ovaries with generous vascular stroma and multiple simple or minimally complicated cysts that may have undergone hemorrhage. The ovarian stroma may appear echogenic and relatively central, surrounded by multiple cysts, resulting in a characteristic “spoke wheel” appearance . The enlarged ovaries are predisposed to torsion and hemorrhage. The incidence of torsion is reported between 3% and 16% .
Theca lutein cysts are associated with gestational trophoblastic disease but can occasionally be seen with a multiple pregnancy, fetal hydrops, or a normal singleton pregnancy (known as hyperreactioluteinalis) . This appearance is also the same as seen with ovarion hyperstimulation syndrome during assisted reproductive thecniques. After the high human chorionic gonadotropin stimulus for their formation is removed, it may take several weeks for the cysts to resolved .