In our centre embryos are usually transferred back into the womb two or three days after eggs have been collected. This has been our routine practice since 1988. With the development of new embryo culture media, we have demonstrated that it may be possible to improve the success of IVF and ICSI treatment by delaying the embryo transfer to five or six days after egg collection. These late stage, pre-implantation embryos are called blastocysts.
Which patients will benefit from a blastocyst transfer?
In our centre we will often make the decision to transfer blastocysts depending on the number and quality of embryos available three days after egg collection. For example if the laboratory team are unable to select the best two embryos for embryo transfer because there are a large number of rapidly developing, good quality embryos on day 3 they may suggest delaying the embryo transfer to day 5 or day 6.
How will it alter my treatment?
Treatment cycles in which blastocysts are transferred are very similar to routine IVF and ICSI cycles. The only difference is that instead of undergoing an embryo transfer on day 2 or day 3 post egg collection it will occur on day five or day six. The embryo transfer procedure itself is the same.
Some patients may not have an embryo transfer because no blastocysts have been formed in the group of embryos that underwent prolonged culture.
Patients having blastocyst transfers in our centre will only be able to have a maximum of two blastocysts transferred. This is because published data indicates that the chances of pregnancy following the transfer of blastocysts are high and therefore there is an increased risk of a multiple pregnancy.
Can I freeze excess embryos?
Yes. As the implantation potential of blastocysts is quite high we recommend freezing any good quality blastocysts that are not used for the fresh embryo transfer. This means that we will recommend the freezing of single blastocysts.
View our Blastocyst Programme results
Are there any risks associated with blastocyst transfers?
The number of blastocyst transfers that have been carried out clinically is still small compared to routine day 2/3 transfers. This means that the risks if any, associated with this technique are unknown. Blastocyst transfers have been carried out for some time in other species. There is an increase in the incidence of monozygotic (identical) twins. In very few cases there may be some risks associated with these pregnancies. Please speak to one of our Doctors or Embryologists should you require further information.