A retrospective analysis of ovarian endometriosis during pregnancy

Objective: To clarify the frequency of pregnancy complicated by ovarian endometriosis and to investigate the size change and outcome of ovarian endometriosis during pregnancy. Design: Retrospective study. Setting: Departments of obstetrics and gynecology of the Osaka University and Izumiotsu Municipal Hospitals of Osaka, Japan. Patient(s): Women who delivered between 1996 and 2007. Intervention(s): None. Main Outcome Measure(s): The frequency of pregnancies complicated by ovarian endometriosis and the size change of the lesions during pregnancy. Result(s): The frequency of ovarian endometriosis-complicated pregnancy has almost quadrupled over the last 12 years, to become the most common adnexal mass detected during pregnancy; it was 0.14% (five cases among 3558 deliveries) during the 6-year period from 1996 to 2001, but has increased to 0.52% (19 cases among 3599 deliveries) during the 6-year period from 2002 to 2007, a statistically significant increase of 3.8-fold. Among 25 ovarian endometriotic lesions observed during pregnancy in 24 women (one case had two lesions), the size of the cyst decreased in 13 lesions (52%), went unchanged in 7 (28%), and increased in 5 (20%), that demonstrated decidualization, abscess and rupture. Conclusion(s): Ovarian endometriosis during pregnancy can be safely observed conservatively; however, further investigation is required to predict the occurrence of abscess formation or rupture of ovarian endometriosis, and to distinguish the enlargements due to malignant transformation from those related to decidualization. (Fertil Steril (R) 2010; 94: 78-84. (C) 2010 by American Society for Reproductive Medicine.)