Sonographic features of tubo-ovarian abscess mimicking an endometrioma and review of cystic adnexal masses.

A 36-year-old female presented with constant, worsening left lower quadrant pain without associated fever or vaginal discharge. Pelvic and transvaginal ultrasound examinations were performed which demonstrated a large complex cystic structure in the left adnexa with peripheral flow on color Doppler imaging. Given the sonographic appearance and patient symptoms, possibilities included endometrioma or hemorrhagic cyst. Tubo-ovarian abscess (TOA) and other cystic ovarian masses were considered less likely. Two days later, the patient returned with severe pelvic pain as well as fever and leukocytosis. Follow-up ultrasound showed enlargement of the mass and a tubo-ovarian abscess (TOA) was suspected. Ultrasound-guided transvaginal abscess drainage was performed with removal of purulent fluid. The case demonstrates that the radiological features of TOA may mimic those of adnexal cystic masses such as an endometrioma or hemorrhagic cyst. A complementary case is also included which demonstrates similar sonographic findings in a patient with endometrioma. In addition to sonographic imaging, a thorough clinical and laboratory evaluation is important in differentiating these entities. Furthermore, we provide a comprehensive discussion about imaging features of cystic ovarian mass on different imaging modalities.