What happens if I produce lots of good quality embryos?
If you have ‘spare’ good quality blastocysts after your embryo transfer then we can freeze and store these for you (with your consent).
Can you freeze all my spare embryos?
We know that only good quality embryos are able to withstand the freezing and thawing process so we do not routinely freeze embryos that are not good quality.
How will you freeze my embryos?
We use a technique to freeze embryos called vitrification as this is associated with the best results of freezing particularly for day 5 embryos, known as blastocysts. Basically, we have to add some harmless chemicals to your embryos to protect them, place them into a plastic straw, and then cool them very rapidly to a temperature of -196°C. They are then stored in liquid nitrogen.
What are the advantages of storing embryos?
The benefit of storing these ‘extra’ embryos is that you will be able to undergo subsequent replacement of thawed embryos without having to undergo ovarian stimulation and the egg retrieval procedure.
What are the disadvantages of storing embryos?
Approximately 5% of embryos do not survive the freeze-thaw process and occasionally all the embryos from one cohort may fail to survive. Another disadvantage is that, just like embryos replaced on a ‘fresh’ cycle, there is no guarantee the embryos replaced will implant. Pregnancy rates are now similar to those following a fresh embryo replacement.
How do you thaw my embryos?
We simply take your straw(s) out of the liquid nitrogen and let them warm very quickly to body temperature. We then remove the protective chemicals that were added before freezing.
Do all embryos survive the freezing and thawing process?
Unfortunately not, however with our latest techniques we expect 92-95% of embryos to survive the freeze thaw process and be available for your treatment. There is no evidence to associate the length of storage with survival, rather it is issues with the embryo and the process of freezing and thawing that determines survival.
Can you re-freeze embryos?
Yes we can. As far as we can tell, providing an embryo has survived the freezing and thawing process, it has the same chance of success as if it was a ‘fresh’ embryo. Providing it is of good quality then it can be re-frozen if necessary.
Are there any risks in freezing or re-freezing embryos?
There is no evidence that freezing embryos is harmful to the baby, but remember that some of your embryos may not survive the freezing and thawing process. As we do not perform re-freezing routinely there is no evidence about whether re-freezing embryos is harmful or not.
How long can embryos be stored for?
Embryos can be stored for initially up to ten years. This storage period can be extended under the following circumstances where the woman being treated, or her partner (if he provided the sperm):
- is likely to develop ‘significantly impaired’ fertility
- carries a significant gene defect
- becomes ‘prematurely and completely’ infertile
For 1. and 2. above, the maximum statutory storage period depends upon the age of the woman at the time the embryos were stored. Embryos cannot be stored past the patient’s 55th birthday and the storage period can only be extended 10 years at a time.
For 3. supporting clinical judgement must be provided in writing, by two medical practitioners (one independent of the unit) who are familiar with the woman and her treatment or partner, their condition and medical history.
The patients whose sperm and eggs were used to produce the embryos must confirm that they have no objection to the embryos being stored for more than 10 years. In addition, the embryos stored for longer than 10 years can only be used for the purpose of providing treatment.
Patients should remember that if they are self-funding their treatment a separate financial contract is made with the storage centre for the length of storage.
Other things you should know
Safety
Although we will do our best to ensure the safe storage of your embryos, we cannot be held responsible for their safety or loss of embryos due to factors beyond our control, such as equipment failure. In addition, we cannot guarantee that your embryos will survive the freeze-thaw process or that a successful pregnancy will result from their transfer.
Contact with the Unit
It would be helpful if you could keep us informed of any changes in your circumstances for example, change of address. This is to ensure we are able to contact you, in order to establish your decision regarding what should happen to the embryos as they reach the end of their statutory storage period. If we are unable to contact you, your embryos will be destroyed at the end of their statutory storage period.
Any other questions?
If you have any other questions about the way in which we freeze and thaw your embryos please speak to a member of staff. You can also visit our Frozen Embryo Treatment page which provides more information and our pricing packages.
