Abstract
The rudimentary uterine horn is a Müllerian anomaly, which is characterized by a partial failure in development and fusion. Pregnancy rarely occurs in this horn, and if it does, it usually ruptures in the first or second trimester of pregnancy. It can be missed during antenatal ultrasound scanning and carries a high risk of maternal and fetal mortality. A 26-year-old gravida 2 para 1 Ethiopian woman presented with a gestational age of 29 3/7 weeks and sudden onset abdominal pain of 9 hours of duration. At presentation, the patient was in hemorrhagic shock with abdominal tenderness and signs of fluid collection, and the fetal heart rate was 124 bpm. The patient's hemoglobin level was 9.4 g/dL. The patient underwent an emergency laparotomy for a ruptured rudimentary horn with active bleeding. Excision of the rudimentary horn was performed, and the mother was discharged with improvement. Although pregnancies in a rudimentary horn rarely progress to the third trimester of pregnancy, this condition should be suspected in patients with hemodynamic instability and abdominal pain. Excision of the rudimentary horn can prevent maternal mortality.