Simultaneous Natural Conception in a Rudimentary Horn and ICSI Pregnancy in a Unicornuate Uterus Managed by Fetocide with Successful Preterm Delivery: A Case Report.

Background: Simultaneous intrauterine and rudimentary horn pregnancies are exceedingly rare, particularly when one arises from assisted reproduction and the other naturally. Early diagnosis is essential to prevent life-threatening complications, such as rudimentary horn rupture. Careful ultrasound evaluation is critical to detect subtle congenital uterine anomalies that may otherwise go unrecognised. Case Presentation: A 39-year-old woman with primary infertility and multiple intramural fibroids conceived naturally and via intracytoplasmic sperm injection (ICSI). Her 43-year-old husband had oligo-astheno-teratozoospermia. After myomectomy and counselling, she underwent donor oocyte ICSI with her husband's sperm; the second cycle resulted in conception. Four weeks later, a transvaginal ultrasound confirmed a viable intrauterine pregnancy. At seven weeks, a second gestational sac was noted in the rudimentary horn. Three-dimensional ultrasound confirmed a unicornuate uterus with a non-communicating rudimentary horn unconnected to the cervical canal or main cavity. At 12 weeks, ultrasound-guided fetocide was performed using 0.2 mL of potassium chloride. The intrauterine pregnancy progressed uneventfully, culminating in a cesarean delivery at 34 weeks of a healthy female neonate weighing 2.3 kg. Both mother and infant remained well at the six-week follow-up. Conclusion: This case illustrates the rare coexistence of a natural rudimentary horn pregnancy and an ICSI-conceived intrauterine pregnancy in a unicornuate uterus. It highlights the importance of detailed, high-resolution imaging, vigilant antenatal surveillance, and timely multidisciplinary management to ensure favourable maternal and fetal outcomes.