A case of two ovarian tissue transplantations that led to a biochemical pregnancy in Japan

Ovarian tissue cryopreservation (OTC) and ovarian tissue transplantation (OTT) are fertility preservation options for prepubertal girls or those in whom cancer treatment cannot be delayed. They are important to increasing number of cancer survivors, but there are very few reports on this topic in Japan. This is the first report of a biochemical pregnancy after OTT in Japan. An 18‐year‐old woman, diagnosed with Ewing sarcoma of the seventh thoracic vertebra, underwent tumor resection. OTC was performed before postoperative chemotherapy. After 7 years, she decided to undergo OTT following the diagnosis of chemotherapy‐induced premature ovarian insufficiency. On postoperative day 104, ovarian stimulation was started, yielding one embryo after 3 days. Embryo transfer was performed during a hormone replacement cycle. At 6 weeks and 1 day, the human chorionic gonadotropin level was 81.5 mIU/mL; however, no gestational sac was observed on ultrasonography, indicating a biochemical pregnancy. Our data will be useful for the further development of fertility preservation options in Japan in the future.