A blastocyst is an embryo that has developed for five to six days after fertilisation.
With blastocyst transfer, embryos are cultured in the laboratory incubator to the blastocyst stage before they are transferred to the womb. At this time, one or two of the best quality blastocysts are selected and then implanted into the woman’s womb.
Blastocyst is the stage just before the embryo hatches the wall and attaches to the wall of the uterus. For embryos to reach a Blastocyst stage it has to survive for 5 to 6 days in the incubator, and since it is ‘the survival of the fittest’, only the best make it that far. Thus, Blastocyst transfer is a means of improving chances of pregnancy!
This is particularly useful for younger women and donor cycles, where there are ample of embryos on day3. Culturing the embryos for 2 more days can be a decision maker, enabling us to transfer the best into the uterus.
We also recommend a blastocyst transfer if you have produced good quality embryos in a previous IVF cycle but they failed to implant in the womb.
Another indication for a blastocyst transfer is in cases where PGS / PGD (Preimplantation Genetic Screening / Diagnosis) has been performed to rule out Genetic disorders on day 3. In such cases we perform an embryo biopsy on day 3, the results for which are available by day 5. Genetically normal embryos can therefore be selected and transferred into the womb on day 5.