How Do You Freeze Embryos?

The ability both to cryopreserve and to thaw eggs, sperm and embryos has revolutionized fertility treatment. In the deep-freeze, the succession of time is almost halted, or at least moving forward at glacial speed. Patients undergoing infertility treatment often ask, “how do you freeze embryos?” and “how do the embryos remain viable years later?”

How Do You Freeze Embryos?

The embryo initially undergoes a process called cryopreservation, which removes water from the cell and replaces it with cryoprotectant. From there the embryo is typically frozen via a technology called vitrification. This high cooling process allows the embryos to turn to a glass like substance instead of ice. The benefit of vitrification is it avoids ice formation while successfully preserving the embryo.

How Are Frozen Embryos Stored?

Traditional “cryopreservation banks” can hold eggs, sperm, and embryos until requested and forwarded to the fertility clinic for use. Fertility clinics can also keep within their tanks, cryopreserved gametes for short-term storage and use.

The tanks themselves tend to be containers composed of layers of stainless steel and/or aluminum that is vacuum-sealed between the insulated layers. The vacuum-seal prevents large temperature changes and minimizes the loss of the coolant that bathes the individualized embryo storage-units. These embryo-storage units (sealed glass straws-most often) live in an admix of liquid Nitrogen (LN2) and its vapors maintain a chilly -196C.

Keeping Frozen Eggs and Embryos Safe

Accredited labs are required to check tanks three times/week and to have continuous monitoring via a temperature probe and alarm. Alarms act on backup power supplies in the case of a power outage, and most deliver remote monitoring and alarm. Additionally, large supplies (tanks) of liquid Nitrogen to maintain the stores must be available. These tank storage rooms are secluded from the functional laboratory proper and, of course, under lock and key.

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Understanding what your options are is the best first step when undergoing infertility treatment. If you have more questions on embryo freezing or what infertility treatment option is best for you, please contact us for an initial consultation. We are here to help.