RESUMO
A unicornuate uterus with an accessory horn is one of the rarest congenital uterine anomalies; hence, the possibility of ectopic pregnancy in the accessory uterine horn is highly uncommon. It poses a significant risk to maternal life, as it is difficult to identify before surgery due to the severe hemoperitoneum in the event of rupture of the ectopic pregnancy. We report a case of a 20-year-old primigravida who presented to the emergency department of Civil Hospital Karachi, with sudden onset of generalized abdominal pain, vomiting, and dizziness at 17 weeks of gestation. Emergency ultrasonography of the abdomen showed extensive echogenic fluid, which was considerably obscuring the view. An empty uterus was seen with a complex cystic mass on its right side separate from the ovary. A ruptured ectopic pregnancy was suspected, and hence, the patient was immediately shifted to the operating room. Emergency laparotomy was done which then showed ruptured ectopic pregnancy with a viable fetus in a right-sided rudimentary horn of the uterus. The horn was excised. The patient recovered well, and the postoperative course was uneventful.