Cryopreservation FAQs

Sperm, egg and embryo cryopreservation offers women and men the freedom and control to pause their “biological clock” until they are ready to start a family. Read some cryopreservation FAQs below and learn more about egg, sperm, and embryo freezing.

How are my eggs/embryos frozen?
Eggs and embryos are frozen in liquid nitrogen using a freezing process called vitrification. This means they are quickly frozen and thawed at several thousand degrees C per minute.

What is liquid nitrogen?
Liquid nitrogen is a colorless clear liquid at extremely low temperatures that is used to freeze eggs, embryos, and sperm.

What temperature is the liquid nitrogen?
Long-term embryo storage is at a temperature of -320F (-196C).

Where are my embryos stored?
All eggs and embryos are stored at one of our Vios IVF centers with well-designed cryopreservation tanks. There are national storage banks as well where some patients choose to store their eggs/embryos for long-term storage.

Who is responsible for freezing and thawing embryos?
The freeze/thaw process is performed by an experienced senior embryologist.

How do you know which embryos are mine in the cryopreservation tank?
All embryos are clearly labeled and catalogued, and may be frozen alone or in a group depending on your future plans. Your eggs or embryos are frozen in a tank with other patients, but all patients storing any tissue have STI testing per FDA requirements.

How are the tanks watched?
As part of our daily quality checks, we physically inspect the level of liquid nitrogen in each of our storage tanks that are either being used for safely storing patient samples. Tanks are topped off weekly to ensure no samples is ever exposed to less than an ideal environment. We have alarm systems attached to our tanks so that in the event of an emergency the proper staff will be alerted promptly. All of our alarm system are connected to emergency backup power along with an internal battery backup.

Is there extra liquid nitrogen on site if needed?
Each location has at least 2 bulk liquid nitrogen tanks on site and these tanks are replaced with full tanks on a weekly basis even if they are not empty to ensure we have plenty of liquid nitrogen available.

Just in case, is there an extra tank to use?
Each Vios location has an empty tank designated as an “Emergency” tank that is kept ready as a backup in the case of just such an emergency.

How do you decide which embryos will be frozen?
Only embryos that have reached certain stages of development will be frozen as they have a strong chance of surviving the freeze/thaw process. Embryos that made it to the blastocyst day (typically a day 5, day 6 or day 7 embryo) have the best post-thaw survival and pregnancy rates. However, your physician may choose to freeze embryos at other stages as well and can discuss this further on an individual basis.

Why does it matter if a cryopreservation tank thaws?
The freezing and thawing process for eggs and embryos is very specific and controlled. The time over which the thaw occurs is critically important and specific protocols are followed. If these protocols are not followed, the egg or embryo quality can be compromised. We typically do a fast freeze and fast thaw process to avoid ice crystal formation and to limit the exposure to the cryoprotectant. Most importantly, the egg, embryo or sperm would not be thawed unless it was being warmed to use it or possibly to perform a brief test like PGS biopsy and refreeze it.

Are there any negative side effects for the embryos with extended periods of storage?
There do not seem to be any negative effects on embryo viability with long-term storage. In fact, a baby was just born from an embryo that was frozen for just over 24 years. Once the embryo is thawed for transfer, it regains its strength and can have the same chance of pregnancy as when it was fresh.

Can I ship my embryos to Vios from other fertility centers?
Vios does accept tissue from other centers as well as prior locations that the physician practiced.  The appropriate FDA requirements and paperwork must be completed and they will be shipped in cryopreservation tanks. We often receive eggs, embryos and/or sperm from other clinics as many come from other clinics for care. We carefully bring the tissue to our lab and care is taken to optimize this transfer. Please speak with one of our embryologists or medical staff if you have further questions about this process.

To learn more about cryopreservation options, schedule a consultation with one of our physicians.