2 The condition, current treatments and procedure
2.1 Some treatments for cancer or other medical conditions can damage the ovaries (gonadotoxic treatment). This can lead to early menopause and infertility.
2.2 There are a number of pharmacologic and surgical strategies that aim to reduce the risk of infertility after gonadotoxic treatment, including ovarian transposition, ovarian suppression and fertility-sparing surgery.
2.3 For people who are going to have treatments that may damage their ovaries, cryopreservation of oocytes or embryos before the treatment begins are options for preserving fertility. These both involve ovarian stimulation, which may lead to a delay in treatment. Embryo cryopreservation also requires sperm from a partner or donor.
2.4 Before starting gonadotoxic treatments, ovarian tissue is removed surgically through laparoscopy, mini-laparotomy, or laparotomy. Usually, at least half of one ovary is removed and the other ovary is left in place to act as a site for future orthotopic autotransplantation. After histological examination of a portion to exclude malignancy, most of the excised ovarian tissue is frozen for future autotransplantation.
2.5 When indicated, the frozen cortical ovarian tissue is thawed and transplanted back to the same person. It can be placed into pelvic sites such as the remaining ovary, ovarian fossa, or broad ligament (orthotopic autotransplantation) through laparoscopy or mini-laparotomy. Alternatively, it can be placed into extra-pelvic sites such as the subcutaneous space of the abdominal wall or forearm (heterotopic autotransplantation). In this case, the follicle and oocyte develop outside the usual environment, so subsequent ovarian stimulation, egg collection and in vitro fertilisation are needed to achieve pregnancy. Another technique involves the vascular grafting and anastomosis of a frozen–thawed whole ovary through mini-laparotomy or laparotomy.
2.6 Future pregnancies may require assisted reproduction technologies, although the procedure can offer the possibility of natural conception.
2.7 Ovarian stimulation is not needed before removal of ovarian tissue for autotransplantation and gonadotoxic treatment can start immediately afterwards. It may be the only fertility preservation option suitable before puberty or for people with oestrogen-sensitive malignancies.