Uterine artery pseudoaneurysm in the setting of deep endometriosis: an uncommon cause of hemoperitoneum in pregnancy

Uterine, ovarian, and placental pathologies are among the differential considerations for a pregnant woman presenting with abdominal and pelvic pain. Imaging plays a key role in the initial work-up of these patients. Sonography is often the first line test; however, evaluation of pelvic pathology can be limited in the gravid state, especially in mid- or late-term pregnancy. We present a case of a pregnant woman who came to the emergency room at 25 weeks with acute abdominal and pelvic pain. Both ultrasound and MR imaging findings revealed intraperitoneal hemorrhage, initially of unknown origin, as well as endometriomas and deep endometriosis. Only postpartum imaging confirmed a uterine artery pseudoaneurysm (PSA) presumably due to decidual reaction in deep endometriosis. We speculate the intraperitoneal hemorrhage was subsequently due to the PSA. This case demonstrates that if hemorrhage is not recognized promptly, it can lead to hemodynamic instability, as well as premature labor and delivery.