Ovarian pregnancy associated with a fresh blastocyst transfer following in vitro fertilization

Ovarian pregnancy is a rare subtype of ectopic pregnancy, and its mechanisms have not been clarified. We report a case of ovarian pregnancy that supports a blastocyst migration mechanism. An infertile woman became pregnant after a single blastocyst transfer following in vitro fertilization during a fresh non-donor cycle. Transvaginal ultrasound revealed a gestational sac-like structure containing an active fetus that was located adjacent to the corpus luteum of the right ovary. Laparoscopy identified a red, swollen implantation site in the ovary, which was completely removed by wedge resection without damaging the remaining parenchyma. This case demonstrated that a fresh blastocyst transferred into the endometrial cavity migrated through the fallopian tube, implanted on an ovarian surface, and formed an ovarian pregnancy.