Sperm cryopreservation, commonly known as sperm banking, is a process that preserves sperm cells for future use. Individuals or couples consider this procedure for various reasons, including fertility preservation before medical treatments like cancer therapy, for military personnel before deployment, elective family planning, or for individuals undergoing gender-affirming care. It offers a way to maintain fertility potential when facing circumstances that might otherwise compromise it.
How Sperm is Preserved
The process of sperm cryopreservation begins with semen collection, typically through masturbation at a clinic, though home collection with rapid delivery to a lab is sometimes possible. Initial evaluation of the semen sample includes analysis of sperm quantity, motility (movement), and morphology (shape) to assess its quality. After collection and analysis, the sperm is mixed with specialized substances called cryoprotectants, such as glycerol. These agents protect the cells from damage by preventing the formation of ice crystals during the freezing process.
The prepared sperm samples are then typically divided into multiple vials and subjected to controlled freezing methods. Slow freezing gradually reduces the temperature, allowing water to exit the cells and minimizing intracellular ice formation. Alternatively, vitrification involves ultra-rapid cooling to create a glass-like state without ice crystals. Once frozen, the vials are immersed and stored in liquid nitrogen tanks, maintaining an extremely low temperature of approximately -196°C (-321°F). At this temperature, the metabolic activity of the sperm cells is virtually halted, preserving their viability for extended periods.
How Long Sperm Can Be Stored
Properly cryopreserved sperm can be stored indefinitely without significant loss of viability or genetic integrity. There is no known biological limit to how long sperm can remain viable when stored correctly in liquid nitrogen. Pregnancies have been reported using sperm stored for decades, with successful cases documented even after 20 years of storage.
Any perceived “limits” on sperm storage are typically due to practical, legal, or administrative factors, not biological degradation. These factors include clinic policies, ongoing storage fees, or an individual’s decision to discontinue storage. Some regulations may set statutory maximum storage periods, which can be extended. The duration of storage does not diminish quality; the initial quality of the sperm before freezing is a more significant factor.
Using Stored Sperm: Key Considerations
When using stored sperm, the thawing process is an important step performed carefully in a laboratory. Thawing involves warming the frozen vials, often in a water bath, to restore the sperm to a usable state. After thawing, sperm motility is re-evaluated to ensure quality for assisted reproductive technologies.
Success rates of assisted reproductive technologies (ART) using frozen-thawed sperm, such as intrauterine insemination (IUI) or in vitro fertilization (IVF), are influenced by several factors. The initial quality of the sperm before freezing and the female partner’s fertility factors often play a more significant role than storage duration. While some sperm may not survive freezing and thawing, typically over 50% of cells survive, which is generally sufficient for fertility treatments.
Legal and ethical considerations are also important. Individuals must provide informed consent regarding storage, disposition, and future use of their sperm, including agreements for cases of death or relationship changes. Ongoing storage fees, ranging from $150 to $500 annually, also apply. Individuals should periodically review their storage agreements and family planning goals.