What is a frozen embryo transfer?
In an in vitro fertilisation (IVF) treatment cycle, any additional suitable embryos not transferred during your cycle can be frozen or ‘vitrified’, using an ultra-rapid freezing technique, for thaw and transfer in subsequent treatments.
In some situations, all of your suitable embryos may be vitrified with none being transferred. The vitrification of embryos at Melbourne IVF has proven to have no significant effect on the ability of an embryo to implant and result in a pregnancy once thawed. The ability of the embryo to implant in a non-stimulated endometrium is thought to be improved.
The advantages of freezing embryos
The likelihood of pregnancy in any treatment cycle is determined directly by the number and quality of embryos transferred. However, increasing the number of embryos transferred must be balanced by a corresponding likelihood of multiple pregnancy (twins and triplets).
Multiple pregnancy is considered a significant medical risk and Melbourne IVF has improved embryo quality to a point where acceptable pregnancy rates are obtained by transfer of a single embryo.
As more suitable embryos than is safe to transfer are usually available in each IVF cycle, the vitrification of additional suitable embryos (that have not been transferred) affords a greater opportunity for pregnancy from each egg collection. Therefore, if multiple viable embryos result from an IVF cycle, your fertility specialist might suggest transferring one or two of them and vitrifying any additional suitable embryos. The vitrified embryos may remain in storage indefinitely without harm and are available for thaw and transfer subsequently without the need to undergo further ovarian stimulation.
If your fertility is at risk due to ovary-damaging cancer treatment then embryo vitrification allows you to preserve your fertility.
Current Victorian legislation allows storage of embryos for up to five years. If you want to store your embryos beyond this time you will need to apply for an extension of the time period from VARTA to authorise Melbourne IVF to continue storing your embryos.
IVF success rates with frozen embryos
At Melbourne IVF a large number of births, over many years, have come from the transfer of thawed embryos. Success rates depend, among other factors, on the age of the woman when eggs are collected and inseminated and the resultant embryos frozen. Therefore, if a 42-year-old woman uses frozen embryos created when she was 38, her chance of pregnancy from those embryos will be that of a 38-year-old woman.
Why freeze all embryos in an IVF cycle?
In some instances, you may undergo IVF and not have an embryo transferred fresh within that cycle. Any and all suitable embryos will be vitrified, in a ‘IVF freeze all embryo cycle.’
Improving embryo implantation
With effective stimulation and embryo culturing methods there may be more embryos from each treatment cycle available for a future transfer. These excess embryos are cryopreserved for use in subsequent treatment where there has been no ovarian stimulation. Whilst methods of freezing and thawing embryos have improved, there is still the small chance that the embryo will not survive the process, so this must too be considered when planning your treatment in consultation with your fertility specialist.
Avoiding ovarian hyperstimulation syndrome (OHSS)
If you have developed a lot of follicles during your stimulated IVF treatment your fertility specialist may recommend a freeze all embryo cycle. This is to avoid the risk of developing ovarian hyperstimulation syndrome (OHSS) which is a potentially dangerous condition that may worsen if you were to become pregnant. By freezing all the embryos and transferring them at a later date when the ovaries are no longer stimulated, it reduces the chances of this condition occurring.