CT Imaging Findings of Ruptured Ovarian Endometriotic Cysts: Emphasis on the Differential Diagnosis with Ruptured Ovarian Functional Cysts

OBJECTIVE: The purpose of this study is to assess the prevalence of abnormal CT findings in patients with surgically proven ruptured endometriotic cysts, as compared with those abnormal CT findings of ruptured ovarian functional cysts. MATERIALS AND METHODS: This study included 13 retrospectively identified patients with surgically confirmed ruptured ovarian endometriotic cysts and who had also undergone preoperative CT scanning during the previous seven years. As a comparative group, 25 cases of surgically confirmed ruptured ovarian functional cysts were included. We assessed the morphologic features of the cysts and the ancillary findings based on CT. RESULTS: For the endometriotic cysts, the mean maximum cyst diameter was significantly larger than that of the functional cysts (70.1 mm versus 36.4 mm, respectively, p < 0.05). The endometriotic cysts frequently had a multilocular shape and a thicker cyst wall, as compared to that of functional cysts, and these differences were statistically significant. Among the ancillary findings, endometriotic cysts showed a significantly higher prevalence of loculated ascites, ascites confined to the pelvic cavity without extension to the upper abdomen, and peritoneal strandings and infiltrations (p < 0.05). Although 11 of the 25 cases of functional cysts showed active extravasation of contrast material at the ovarian bleeding site, only one of 13 cases of endometriotic cysts showed active extravasation. CONCLUSION: The diagnosis of ruptured endometriotic cyst should be suspected for a woman in whom CT reveals the presence of multilocular or bilateral ovarian cysts with a thick wall and loculated ascites confined to the pelvic cavity with pelvic fat infiltrations.