Recurrent Heterotopic Pregnancy Following Frozen-Thawed Embryo Transfer: A Case Study and Comprehensive Literature Review.

BACKGROUND Recurrent heterotopic pregnancy is a serious and rare pregnancy complication that occurs after in vitro fertilization and embryo transfer, posing a great threat to the safety of the mother and intrauterine fetus. We report a case of recurrent heterotopic pregnancy after in vitro fertilization and embryo transfer. We also reviewed the literature to explore the causes, diagnosis, treatment, and prevention of recurrent heterotopic pregnancy. CASE REPORT A 32-year-old woman with tubal factor infertility underwent in vitro fertilization and embryo transfer. Oocyte extraction was performed twice, while embryo transfer was performed 4 times, with 2 embryos transferred each time. No pregnancies occurred during the 2 fresh embryo transfer cycles; however, heterotopic pregnancies occurred during both frozen-thawed embryo transfer cycles. Ultrasonography detected only the first heterotopic pregnancy, at 6 weeks after embryo transfer. As the intrauterine embryo had stopped developing, laparoscopically monitored dilatation and curettage and removal of the affected fallopian tubes were performed. The second heterotopic pregnancy was detected 3 weeks after embryo transfer, guided by the ultrasound examination conducted earlier. After timely surgical treatment, a live birth occurred. CONCLUSIONS This case and review of the literature elucidates the importance of considering the possibility of a heterotopic pregnancy during ultrasound examinations, especially in patients who utilized assisted reproductive technology to transfer multiple embryos.