Cryopreservation of Sperm & Embryos
Ejaculated sperm found in semen have been cryopreserved clinically since the 1980s. Depending on the number and quality of the thawed semen, the attempt to produce a pregnancy in the partner will either be by simple timed insemination or by in vitro fertilization.
Testicular sperm can be recovered surgically from some but not all men with azoospermia (absence of sperm in the semen). Testicular sperm, when present, are usually suited to cryopreservation but will be few in number and will therefore require in vitro fertilization with ICSI to attempt to create a pregnancy. Our Virginia fertility clinic provides semen cryopreservation services.
It is generally believed that the cryopreservation process itself does not increase the risk of birth defects in children conceived with thawed sperm.
Oocyte (Egg) Cryopreservation
Oocyte cryopreservation provides the opportunity to conserve patient's eggs or oocytes at very low temperatures for future attempts at conception using IVF. Unlike sperm cryopreservation, egg freezing has a very short history. Between 100 and 200 children have been born worldwide following egg freezing. Although these children do not appear to exhibit unusual health problems, there is not enough data to conclude that this method is safe. Therefore egg freezing is considered experimental and patients who request oocyte cryopreservation will be offered the procedure as part of a research protocol.
Egg freezing requires that the patient undergo ovarian stimulation and surgical procedures to acquire the oocytes. The oocytes are chilled by one of two methods, slow-rate cooling or ultra-rapid freezing (vitrification). Upon thawing, in vitro fertilization procedures are needed to inseminate the eggs and to culture resultant embryos. Selected embryos may then be transferred into the patient's uterus.
Oocyte cryopreservation is appropriate for women under 30 years of age who wish to defer family building into later years when ovarian output may decline, for couples who wish to limit the number of embryos created by assisted reproduction, or for women facing treatment such as cancer therapy that may diminish ovarian function.
Embryos can be cryopreserved and stored at very low temperatures to provide future opportunity for achieving conception. Embryo freezing is usually part of the in vitro fertilization and embryo transfer strategy when the number of high quality embryos exceeds the number required for immediate transfer into the uterus. Cryopreservation of human embryos has been shown to be a successful procedure and there are no reports of increased birth defects in pregnancies achieved through this process.