Ovarian Cryopreservation

Ovarian tissue collection for cryopreservation is a technique for fertility preservation. Gonadal tissue is collected laparoscopically, then is processed and cryopreserved and it can be reimplanted to restore endocrine and reproductive function. Patients eligible for this procedure are all those females, especially prepubertal, who are exposed to a risk of premature ovarian failure. Premature ovarian failure is associated to exposure to chemiotherapics and radiation [1, 2] (Tab 1). Ovarian tissue cryopreservation was firstly described in 1996 by Hovatta et al. [3] Even if this technique is still to be considered experimental, it is currently the only option applicable in prepubertal girls. The feasible techniques for tissue collection are mainly 3: - Ovarian cortical tissue biopsy: it consists of obtaining several specimen of cortical tissue away from the hilum using a laparoscopic biopter. - Partial oophorectomy: it consists of partial excision of ovarian cortical tissue. Different authors report from 1/4 to 2/3 of ovarian tissue to be removed leaving the hilar part intact - Unilateral ovariectomy: it consists of the collection of the whole ovary including vascular pedicle that will be used during the reimplantation. The collected tissue is then harvested and prepared for cryopreservation. The most used method is slow freezing, which represents the standard of care, but also vitrification is an available method [4] Vitrification difers from slow freezing for concentration of cryoprotectant (higher in vitrification and rate of cooling (faster in vitrification) [5]. The tissue can be cryopreserved for about 7 years [5]. When the fertility has to be restored, after the end of therapies, the harvested tissue can be reimplanted in an orthotopic or heterotopic position. The rest of the native ovary or a peritoneal fold near the fimbriae are considered orthotopic positions as they allow spontaneous pregnancies. Forearm or abdominal wall are the most used heterotopic sites. The reactivation of the tissue appears 4 to 9 months after the reimplantation [5].

Ovarian tissue collection for cryopreservation is a technique for fertility preservation. Gonadal tissue is collected laparoscopically and then is processed and cryopreserved, and it can be reimplanted to restore endocrine and reproductive function.