Oocyte and ovarian tissue cryopreservation for children

Abstract

In recent years, along with the overall spread of fertility-sparing therapy, fertility-sparing therapy has also been applied to pediatric patients. Oocyte and ovarian tissue cryopreservation are indicated in girls. Oocyte cryopreservation is a well-established medical technique; however, it cannot be applied to urgent care patients because the controlled ovarian stimulation necessary for oocyte pick-up takes about two weeks. In addition, other conditions are necessary for its implementation, such as having a menstrual cycle and being able to undergo vaginal egg retrieval. In addition, the pregnancy rate from oocyte cryopreservation is fairly low. In contrast, ovarian tissue cryopreservation can be performed even in pre-menarche patients, and the number of days required for preservation is low. However, with diseases that tend to have minimal residual presence in the ovary, such as leukemia, tumor cells may be mixed in with the preserved ovarian tissue, and in some cases the original disease can recur through their transplantation. Our institution has already performed ovarian tissue and oocyte cryopreservation for 78 and 4 children, respectively, and its feasibility has been demonstrated. Reliable registration in a registry system and long-term follow-up are also important for establishing evidence in Japan.