OVARIAN TISSUE FREEZING
Ovarian tissue freezing refers to freezing a part of or the entire ovary for the purpose of fertility preservation. It is an experimental procedure and since its introduction in the early 2000s, there have been limited number of births following the transplantation of frozen-thawed ovarian tissue. In some of these cases, one of the ovaries was removed and transplanted back into the pelvic area following chemo or radiation therapy. Therefore, in some of these cases the ovary that was left in-situ may have given rise to the pregnancy rather than the frozen-transplanted ovarian tissue, especially in those who received fertility medications resulting in multiple ovulations from both ovaries.
Whereas this technology is still in its infancy and considered experimental, the following are some of the potential indications:
- Patients who are planned to receive chemotherapy and/or radiation therapy
- Patients undergoing bone marrow or stem cell transplantation
- Patients who are planned to undergo removal of one or both ovaries
- Patients who will be exposed to chemotherapy for non-cancerous diseases
Ovarian tissue freezing is conducted by surgical removal of the ovaries followed by removal of the stromal layer of the ovary, leaving the cortical part for freezing. Next, the ovary is cut into small pieces and frozen in liquid nitrogen. When chemotherapy and/or radiation treatment is completed and the patient is ready for pregnancy, tissue is thawed and transplanted surgically. Hormone levels can be measured and egg development can be monitored to assess if the transplanted ovary resumes its function.
If the tissue is transplanted back into the pelvis, spontaneous pregnancy may be observed. If the tissue is placed outside of the pelvis, ovaries may be stimulated with hormone treatment and in vitro fertilization (IVF) may be attempted to fertilize the egg, create an embryo and transfer into the uterus. A limited number of pregnancies have been reported with ovarian tissue freezing and the success rate is considered to be very low.
A detailed discussion with a fertility specialist is recommended for all individuals at risk for losing their fertility potential. There are many options available to both men and women including sperm, egg and embryo freezing. Additionally, third party reproduction– which includes using donor sperm, donor eggs and donated embryos– is always an option. Gestational surrogacy is also an option for women who are unable to carry a pregnancy to term or those exposed to high doses of chemotherapy that damaged their uterus.
Alternatively, egg freezing can be considered for patients who are thinking about ovarian tissue freezing. Egg freezing has become an excellent choice for women at risk of losing their fertility potential. Most of the indications for ovarian tissue freezing are also applicable to egg freezing with high success rates. It can be completed before the initiation of chemo-radiation therapy and frozen eggs can be stored for many years until pregnancy is desired. Based on our reported data, delivery rates up to 75% can be observed following egg freezing. Babies born through frozen eggs have the same risk of having birth defects compared to the general population.