Cryopreservation is the process of freezing eggs, sperm or embryos to sub-zero temperatures for later use. When the eggs, sperm or embryos are needed, they are thawed and fertilized or used in a fertility treatment cycle. Sperm may be used for intrauterine insemination (IUI) or in vitro fertilization (IVF) procedures. Eggs and embryos will be used during in procedures associated with IVF.
Cryopreservation provides indefinite longevity for the cells being frozen. At the time of freezing, all biological activity is suspended until the cells are thawed.
If a woman decides to freeze her eggs, she must take medications daily for a number of days to stimulate her ovaries to produce many more eggs than normal. This is the same preparation used for an egg retrieval in IVF. Once the eggs are thought to be mature, they are removed from the ovarian follicles and frozen by embryologists in the laboratory. Embryologists most often use vitrification to prepare the oocytes for storage. The oocytes may be stored at the fertility clinic in liquid nitrogen storage tanks or at a commercial cryopreservation bank until needed by the woman or couple for IVF treatments.
If a man decides to preserve his sperm, he can provide a sample for cryopreservation. However, if no sperm are present in the semen or he cannot ejaculate, a surgical sperm extraction may be used to remove sperm directly from the testicle. The sperm sample is then frozen and stored at a fertility clinic or sperm bank until ready to be used for intrauterine insemination (IUI) or IVF..
To preserve embryos, eggs are collected as described above. In the IVF process, once the eggs are collected, they are fertilized with the partner's sperm in a lab. The resulting embryos are cultured for a few days, allowing the cell division process to reach optimal conditions before the embryos are frozen and stored at a fertility clinic or cryopreservation bank until they are to be transferred into the female's uterus at a later date.
Chemotherapy and radiation can damage a person's fertility during cancer treatment. Cryopreservation allows cancer patients to preserve their fertility with the following options: