Acute abdomen or life-threatening heterotopic pregnancy with tubal rupture: where does imaging play a role?

Heterotopic pregnancy (HP) is a rare, potentially life-threatening complication of an intrauterine pregnancy with a simultaneous ectopic pregnancy. There is a higher incidence with assisted reproduction techniques (ART) and radiology can be pivotal in its diagnosis. A 28-year-old woman underwent ART and at 7 weeks' gestation presented with acute right iliac fossa pain. Transvaginal ultrasound (US) imaging confirmed a viable intrauterine pregnancy. The patients' pain persisted however, and transabdominal US demonstrated a complex, heterogeneous right adnexal mass. Subsequent magnetic resonance imaging (MRI) confirmed an HP with a ruptured ectopic and haemoperitoneum. Emergency laparoscopic surgery and right salpingo-oopherectomy were performed without complication. We highlight the importance of considering HP as a diagnosis in the acute gravid abdomen, especially when initial investigations have confirmed a viable intrauterine pregnancy. Furthermore, this case highlights MRI as a useful modality in complex cases due to its high soft tissue contrast resolution using non-ionising radiation.