Differentiation of Tuboovarian Abscess from Endometriosis: CT Indicators

ABSTRACT

PURPOSE: To assess and compare CT findings of surgically confirmed cases of tuboovarian abscesses (TOA) and endometriosis in order to identify indicators which may be helpful in making correct preoperative diagnoses. MATERIALS AND METHODS: Of the 35 consecutive patients with surgically confirmed TOA, CT images were available for 11 of those patients. As a comparative group, 36 patients with surgically confirmed endometriosis with CT images were selected. CT images of TOA were compared with those of endometriosis. A retrospective analysis of the CT images of both groups was performed without knowledge of the pathologic diagnosis. The analysis compared the thickness and enhancement pattern of the cyst wall, attenuation of the cyst content, size and shape of the cyst, and paraaortic lymphadenopathy. RESULTS: Mean thickness of the cyst wall was 6.2+/-2.0 mm in TOA and 4.5+/-2.4 mm in endometriosis. Multilayered appearance in both diseases was seen on enhanced CT in 91% (10/11) of TOA cases and in 25% (9/36) of endometriosis cases. Hounsefield units of the cyst contents were 20.0+/-5.5 HU and 24.7+/-10.0 HU for TOA and endometriosis, respectively. Mean diameter of the cysts was 7.5+/-1.7 cm in TOA and 7.9+/-3.1 in endometriosis. Shape of the cyst was multilocular in 82% (9/11) of TOA cases and in 75% (27/36) of endometriosis cases. Paraaortic lymphadenopathy was present in 73% (8/11) and 44% (16/36) for TOA and endometriosis, respectively. CONCLUSION: TOA should be suspected on CT when a multilocular cystic ovarian mass is observed, especially if the lesion has a thick wall and has a multilayered appearance, and is accompanied by paraaortic lymphadenopathy.