Freezing and Storage of Embryos
When you first visit your Unit to discuss your future treatment, the clinician will discuss with you the possibility of embryo freezing. During IVF or ICSI, ‘extra’ embryos may be produced, some of which may be suitable to be frozen and stored for your future treatment.
What is involved in embryo freezing
The freezing (also known as cryopreservation) of ‘extra’ embryos involves cooling them and storing them at very low temperatures. This technique enables us to keep ‘extra’ embryos as best as we can.
What are the advantages of storing embryos?
The benefit of storing 'extra' embryos is that you will be able to undergo subsequent replacement of embryos without having to undergo ovarian stimulation and egg collection.
Putting straws containing frozen embryos into storage.
What are the disadvantages of storing embryos?
Approximately 30 % of embryos do not survive the freeze-thaw process and occasionally all the embryos from one patient may fail to survive. Another disadvantage is that there is no guarantee that when the embryos are replaced they will implant. Pregnancy rates are generally lower than those following fresh embryo transfer.
How long can embryos be stored for?
Embryos can be stored for years but the normal maximum statutory period under the 1990 Human Fertilisation & Embryology Act is five years. This storage period may be extended under the following circumstances where the woman being treated, or her partner (if he provided the sperm):-
- (a) Is likely to develop ‘significantly impaired’ infertility
- (b) Carries a significant gene defect
- (c) Is likely to become ‘prematurely and completely’ infertile
For (a) and (b), the maximum statutory storage period depends upon the age of the woman at the time the embryos were stored. If she is 45 years or under at the time the embryos were first stored, the period is 10 years. However, if the woman is 46 years or over at the time the embryos were stored, the period is determined by the date the woman being treated becomes 55.
For (c) the maximum storage period can be more than 10 years. However, supporting clinical judgement must be provided in writing, by two doctors (one independent of the unit) who are familiar with the woman and her treatment or partner, their condition and medical history. The man and the woman whose sperm and eggs were used to produce the embryos must confirm in writing that they have no objection to the embryos being stored for more than 5 years. In addition, the embryos stored for longer than 5 years can only be used for the purpose of providing treatment.
Senior Embryologist safely locking an embryo storage vessel.
Where are embryos stored?
All embryo freezing and storage takes place at the Hewitt Centre in Liverpool.
Contact with the Hewitt Centre
You must keep the Hewitt Centre informed of any change in your circumstances eg change of address. This is because we will contact you annually to check that you still wish your embryos to remain in storage. If we are unable to contact you, your embryos will be removed from storage when they reach the end of their statutory storage period.
If there are any further questions you have regarding embryo storage, please contact the Hewitt Centre on 0151 702 4256.