What is Frozen Embryo Transfer? (FET)
Frozen Embryo Transfer, or FET for short, is for patients who have already undergone In Vitro Fertilisation (IVF) or Intracytoplasmic Sperm Injection treatment (ICSI). That’s because the process involves using embryos that have previously been cryopreserved (frozen) at the end of a fresh cycle.
What is the process of FET?
Frozen Embryo Transfer (FET) most commonly involves the use of hormones to try to create an optimal environment within the patient’s uterus to accept an embryo without the need for an egg collection. This means that a previously frozen embryo(s) (fertilised egg(s)) can then be placed into the uterus and develop the same way as it would have done if it had been chosen for fresh transfer.
As part of this process, you may be given hormones to help your uterus accept the embryos. However, if your cycle is regular, a frozen embryo may be placed in the uterus without hormone intervention. At Leicester Fertility Centre, we only offer natural cycles in very rare cases.
On which day of your cycle is Frozen Embryo Transfer done?
Each person is unique, and it means that you could either have a long or short drug protocol prior to transfer. The difference between long or short protocol is in the medications that are used to suppress internal hormones. However, the aspect of stimulating the lining of the uterus is the same for both.
With each cycle, you will have to be monitored and will be given medications to help thicken the lining within the uterus. A transvaginal scan will be booked to ensure this is going to plan and, if it is, you will then be given a date for embryo transfer. Transfers normally happen either on a Tuesday or Thursday at LFC, but cycles can be manipulated to accommodate specific requirements (for example, a transfer under sedation which will require a theatre slot and it’s the same for fresh collection).
In addition, the stage at which your embryos were frozen will also determine when they are thawed and transferred to you.
The embryologist will contact you the day before to confirm how many embryos are to be thawed, as well as giving you the time and date of your transfer. You will then attend the unit for that agreed appointment to have your embryo(s) replaced.
Normally, only the number of embryo(s) required for transfer are thawed. However, some embryos don’t like undergoing the freeze/ thaw process so it may be necessary to thaw more than that. The embryologist will confirm with you at transfer exactly how many had to be thawed and the fate of each embryo.
Should no embryos survive the thawing process, a follow-up appointment will be made with a doctor. This will require you to stop taking any medications you are on while we discuss options with you. This can often come as a shock and our specially-trained counselling team, alongside the rest of Leicester Fertility centre, will be on hand to support you through this time.
How long does it take for the embryo to implant after FET?
Each embryo is unique but implantation normally happens when the embryo is between 7-11 days old; so if it was frozen on day 5 (blastocyst), then it will hopefully implant 2—5 days after transfer.
You will need to continue with medication such as progesterone pessaries or injections for a further two weeks after this. You will also be given a date to test, when you will learn whether the embryo has implanted successfully and whether you have become pregnant and are starting your fertility journey. If you are pregnant, you will be on medication until you are around 12 weeks pregnant.
For a full run-down of the process of FET, what it involves and further information, you can read our patient leaflet here.
How successful are Frozen Embryo Transfers?
Like with any fertility treatment, Frozen Embryo Transfer does not have a 100% success rate. No treatment is guaranteed to result in pregnancy, due to the complex dependencies involved and the uniqueness of every patient or couple.
There are factors that can influence how successful a treatment is likely to be, such as age or the quality of the embryos, but it is always our recommendation to speak with a clinician and explore what the right route of treatment might be for you.
If you’d like to get in touch with our team of fertility experts to explore your options, please do so here.