Semen cryopreservation is a method used to preserve sperm by freezing them. Once thawed, the sperm generally remain capable of fertilizing an egg and producing a healthy child. There are many reasons why men preserve their sperm, but men who who undergo semen cryopreservation generally have some reason to believe that they may no longer be fertile in the future. Semen is typically collected and stored at semen storage facilities commonly known as sperm banks, where frozen semen can typically be kept usable for years.
The preservation of semen samples through freezing is typically performed via one of two methods. The method known as slow programmable freezing (SPF), typically involves freezing the sample slowly and in a carefully controlled manner. A newer method, known as vitrification, generally involves flash-freezing the semen sample. Vitrification is considered a more viable option, since the sperm generally survive the process more easily.
Frozen sperm can often be used to fertilize eggs for years after its initial preservation. Most storage facilities offer semen cryopreservation clients the option to store sperm for one to five years or more. Sperm are usually frozen in a cryoprotectant solution containing ingredients such as sucrose, glycerol, and soy lecithin. It is believed that this solution allows sperm to be successfully thawed and re-frozen up to three times without causing them significant damage.
Semen samples for cryopreservation are generally obtained by masturbation. Some facilities provide private areas where men can extract samples, while others allow the extraction to take place in the home. Most facilities screen donors for contagious viral diseases before accepting sperm for freezing. Two to five days of sexual abstinence are typically recommended prior to sample collection.
Men typically choose semen cryopreservation for a number of reasons. Some men may donate sperm that will be sold anonymously to women who wish to conceive without a male sexual partner. Men who undergo surgical sterilization are often advised to preserve semen, in case they change their minds in the future and decide they want to sire children. Men who are about to receive chemotherapy and radiation treatments for testicular or other cancers may also preserve sperm in a storage facility, since cancer treatments can permanently damage fertility. Those who find themselves exposed to high levels of radiation or toxic chemicals regularly, such as in the workplace, may choose to preserve their future fertility via semen cryopreservation.