Sperm cryopreservation is a method of preserving sperm. The sperm receive freezing treatment that prevents degradation and then are thawed out for use when necessary. This is a common technique in cases where a man wishes to store sperm prior to cancer treatment or where couples require additional help to conceive a child.
As long ago as the 1950s, scientists used sperm cryopreservation as part of human fertility treatments. When frozen correctly, sperm can become frozen at a moment in time in their lifespans and remain viable for years. Liquid nitrogen is the freezing method of choice for sperm cryopreservation.
Men who wish to avail of sperm cryopreservation may have medical conditions or fertility problems. For instance, chemotherapy drugs or radiation as part of a cancer treatment program can adversely affect the quality or amount of sperm produced. A man may therefore want to create a stockpile of good-quality frozen sperm so he can use it as part of a future pregnancy with his partner.
Fertility problems can also affect sperm quality, and men with low sperm counts may be able to build up a decent-sized stockpile under cryogenic preservation for future use in fertility treatments. Stockpiles of good-quality sperm, even if the man has no fertility issues himself, may also be practical to have for use when the woman in the couple has fertility problems. Eggs can also be frozen in the same way.
Each sperm sample is mixed with a substance like glycerol, which protects the sperm from damage in the cold temperatures. The sperm is contained in small vials and kept in a freezer container that is full of liquid nitrogen. This liquid nitrogen keeps the sperm frozen to a very low temperature. Low temperatures, such as the -320 degrees Fahrenheit (about -196 degrees Celsius) that liquid nitrogen achieves, keep the sperm healthier for longer than higher temperatures. Risks include the possibility that the storage freezer can break down.
When the sperm is required for fertility treatments, technicians remove the vial and thaw the sperm out. Typically, about half of the sperm do not survive the cryopreservation process. Various types of fertility treatments can be performance with the live, thawed-out sperm. These range from simple intrauterine insemination, which the woman can perform herself, to a more complicated procedure such as in vitro fertilization, where the egg is first removed from the woman and then injected with one particular sperm in a petri dish.