Frozen Embryo Transfer (F.E.T.)
After embryo transfer there may be surplus embryos, some of which we will be able to freeze. These embryos will have to reach the hospital’s criteria for freezing to give them the best chance to survive the freeze-thaw process.
There is a legal requirement to obtain consent from both partners prior to embryo storage. The hospital also has a freezing contract that you will be asked to sign when freezing is to be undertaken. You will be given copies of these forms for your records. You will be sent an annual letter regarding your stored embryos as per HFEA guidelines. A fee will be payable for this service.
The advantage of storing embryos is the avoidance for repeated drug stimulated treatment cycles.
At the fertilisation call you will be asked to reaffirm that you and your husband / partner have consented to the freezing of embryos and to understand that it is St. Jude’s policy not to freeze less than 2 embryos unless instructed by yourselves. The cost for freezing embryos stays the same regardless of how many embryos are frozen. If you do want one embryo frozen this must be stated on the HFEA 00(6) and 00(7) consent forms.
Embryos are frozen under controlled conditions and are stored in liquid nitrogen at -196ºC; this halts any further development of the embryo and can be stored for many years without harming them. Once frozen, embryos can be requested to stay in storage for up to 5 years from the outset. If you want storage for longer than 5 years then this must be discussed with the clinician and the HFEA consent form (96)8 must be completed and accompany the other HFEA consent forms, 00(6), 00(7).
The hospital has in place strict control procedures to ensure identification and labelling of all gametes/embryos in accordance with HFEA guidelines. We also have in place an alarm system that will alert on call staff out of hours of any untoward emergencies. Whilst every effort will be made to ensure the safety of your embryos at all times we are unable to make 100% guarantees.
Unfortunately not all embryos will survive the freeze-thaw process. The survival rate of embryos is approximately 65% and some patients’ embryos will not survive the freeze-thaw process at all. It has been well documented that if there is 50% cell loss to the embryo after thawing then it is unlikely to achieve a pregnancy. Also, if there are only a few embryos in storage it might be that none will survive. We do not fully understand why this happens and it may be necessary to thaw more than the required number of embryos to be able to transfer the best two.
On the day that the embryos are thawed the embryologist will inform you of how many embryos needed to be thawed and how many have survived. Because of the delicate nature of the freeze-thaw process it is important that the embryologist informs you at home. It may be advisable if someone could be with you just in case it may be bad news. Alternatively, if you cannot be at home then you must make arrangements yourself to ring the hospital on 01902 620831.