Introduction: A cornual pregnancy describes a rare ectopic location positioned within the myometrium next to the fallopian tube, which can be difficult to find on traditional ultrasound imaging. Given its location and the stretch within the uterine wall, cornual pregnancies can progress for weeks prior to diagnosis. Ruptures can, therefore, be catastrophic with disproportionally high maternal mortality rates compared to other ectopic pregnancies.

Case Report: A 34-year-old female recently treated with methotrexate for ectopic pregnancy presented to the emergency department (ED) for acute onset of lower abdominal cramping without vaginal bleeding. She arrived clinically stable and quickly decompensated with witnessed syncope in the ED, prompting point-of-care ultrasound showing free fluid in the abdomen. The patient was taken for emergent surgery by obstetrics while receiving transfusion of blood products for suspected ruptured ectopic pregnancy. A fetus estimated to be 10 weeks of age was discovered in the left cornual region. Approximately two liters of intraperitoneal blood were drained without complication.

Conclusion: Cornual pregnancy is a difficult to diagnose but potentially disastrous type of ectopic pregnancy due to massive hemorrhage. Emergency clinicians should be aware of this condition given its rare occurrence but potentially catastrophic outcomes.