Embryo Freezing & Embryo Storage
Often after a cycle of IVF or ICSI, there are a number of successfully fertilised embryos that we can freeze and store for your future use.
Whether your cycle was successful or unsuccessful, frozen embryo transfer gives you another chance of pregnancy from the initial egg collection with a much reduced cost and without having to go through an egg collection again.
The pregnancy rates at the CRGH for frozen embryo transfer are shown in this chart.
There are two methods of embryo freezing: slow freezing and vitrification. Slow freezing has been used for many years with good results, but vitrification is a newer method showing much higher success rates – often as high as fresh transfers. The CRGH was one of the first centres in the UK to introduce vitrification. Staff from the CRGH went to Japan to learn the procedure.
The embryologist will decide if any of your embryos are suitable for freezing. They do need to be of good quality as poor quality embryos do not survive the freezing/warming process. Embryos can be frozen at various stages between the cleavage stage (day 2, at about 4 cells) to the blastocyst stage (day 5 or 6). Embryos can be stored frozen for up to ten years.
When you come through for a frozen embryo transfer cycle, the clinical staff at the CRGH will monitor your cycle closely to ensure that the womb is at the best stage for embryo transfer. They may give you some drugs to help build up the lining of the womb or you may have a natural cycle. You will have ultrasound scans to determine if you are ready for the transfer. At this time, the embryologist will warm the embryos. They may have to warm more than one to help choose a really good quality embryo for transfer. Occasionally embryos do not survive the freezing/warming process.
The embryo(s) are transferred in the same way as for your fresh cycle. You may be given some extra drugs, such as progresterone patches, to help keep the lining of your womb optimal for implantation. As with a fresh cycle, you will the have a pregnancy test two weeks after the transfer.
To freeze embryos, you must give written consent for the CRGH to store your embryos and for their future use. You must keep in regular contact with the CRGH so that we know if you have moved house or if any of your circumstances have changed. Once the statutory period is up, we do not need your consent to remove the embryos from storage.
At the CRGH we hope that you are successful from your frozen embryo cycle and hope that you may achieve more than one pregnancy from one full cycle of IVF/ICSI.