Frozen Embryo Tranfers (FET)
What is Frozen Embryo Transfer (FET)?
Frozen Embryo Transfers (FETs) are when you use embryos that have been cryopreserved, from a previous IVF/ICSI cycle. They are thawed, checked to ensure that they have survived and are growing, and transferred into your uterus.
The whole process is a lot simpler than an IVF cycle as you do not need to take the follicular stimulating hormones that you previously self-injected to produce the eggs, and you do not need to have the procedure to retrieve the eggs from your ovaries. Instead, you will take hormones to build your uterine lining in preparation for receiving the embryos. You will still need to be monitored by ultrasound to check progress.
Freezing is now an essential part of every clinic’s IVFprogramme. Studies have proven that results are the same if not better when embryos are transferred in cycles rather than directly following egg collection. Thanks to improved freezing techniques.
* Cryopreservation: The process of cooling and storing cells, tissues, or organs at very low temperatures to maintain their viability.
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Frozen Embryo Transfer process
Thawed embryos may be replaced during a natural cycle (without drugs) or in a cycle primed with hormone supplements. Depending on your recommended treatment by your specialist.
The frozen embryo transfer itself is the same procedure as an embryo transfer in a fresh cycle. Once the embryo is thawed, a catheter holding the embryo is gently inserted into the cervical channel and into the uterine cavity guided by ultrasound. The catheter is then removed and checked to make sure the embryo has been transferred. After the transfer, you can return to normal with the embryo quite safe within the uterus. Following embryo transfer, a pregnancy test is usually arranged twelve to fourteen days later.
Does the length of embryo storage matter?
No. Successful transfers are not dependent on the length of time embryos have been frozen. They are stored in temperatures close to -200 Celsius and will not deteriorate over time. Many people will store embryos for use years in the future when they are ready to start or add to their family, with no effect on their quality or viability. According to the HFEA, embryos can be stored for up to ten years.
How Many Embryos To Transfer For FET?
By law, you may transfer one or two, or if you are over 40 you may transfer three. At The Sussex Downs Fertility Centre we generally transfer only one embryo at a time, to avoid the likelihood of twins. However, it is your choice and our guidance will consider your age and the embryo quality. The number of embryos transferred will depend on several factors: your age, the embryo quality and how many have survived the thaw.
