Diagnosis and management of a heterotopic pregnancy and ruptured rudimentary uterine horn.

Background: Heterotopic pregnancies implanted in a rudimentary uterine horn account for 1 in 2-3 million gestations, and confer significant risk of morbidity due to uterine rupture and hemorrhage.

Case presentation: A 34-year-old nullipara presented with acute pelvic pain at 17 weeks of gestation with dichorionic-diamniotic twins, one in each horn of an anomalous uterus first diagnosed in pregnancy as bicornuate. Three-dimensional ultrasound and MRI revealed myometrial disruption in the left rudimentary uterine horn, and the patient underwent an uncomplicated abdominal hemi-hysterectomy. Fourteen days later, an uncomplicated dilation and curettage was performed for a fetal anomaly in the remaining twin in the right unicornuate uterus.

Conclusion: This case demonstrates the utility of magnetic resonance imaging and three-dimensional ultrasound in the assessment of myometrial integrity in a gravid patient with a heterotopic pregnancy and ruptured rudimentary uterine horn. This case demonstrates the importance of pre-pregnancy diagnosis and management of mullerian anomalies.