Challenges in diagnosis and management of a retroperitoneal pregnancy.

An ectopic pregnancy in a retroperitoneal location is an extremely rare and life-threatening situation. Here, we present a case report of a nulliparous woman in her 30s who presented with rising β-human chorionic gonadotropin (hCG) titre after embryo transfer but with no pregnancy detected on transvaginal scan. She was referred to us after two negative laparoscopies done outside and finally an MRI revealing a retroperitoneal pregnancy embedded close to the aorta near the origin of the left renal artery. As parenteral methotrexate had no effect, an ultrasound-guided intrasac methotrexate instillation was done. Though the hCG levels fell to near normal levels, the sac did not regress and seemed to increase in size. Laparoscopic removal was attempted, but the intraoperative bleeding necessitated an open procedure. This case highlights the diagnostic difficulty, limitations of systemic methotrexate in retroperitoneal ectopic pregnancies and the need for individualised multidisciplinary management.