Blastocysts are embryos which have grown till day 5 or 6 after fertililization.
Normally in an IVF cycle on the day of egg pick up, sperms are injected into eggs through the process of ICSI. Next day fertilization check is done and embryos are cultured in the incubator. Blastocyst or extended culture as we say it is taking the embryos till day 5 of culture to select the best embryo available for freezing or transfer.
Are Day 3 embryos better or day 5?
As we do extended culture of embryos, only those embryos which have the potential to implant inside uterus will go on to form blastocysts. Hence a natural selection helps us in selecting the best embryos to transfer. As there is embryonic activation blastocysts can result in better pregnancy rates. So it does improve pregnancy rates.
When should you go for blastocysts in IVF?
It is always a better idea to go for blastocysts than day 3 embryos. However in patients at higher age or in patients with repeated IVF failures, it is always a good idea to opt for blastocyst culture. Also in patients trying to avoid multiple pregnancy in IVF blastocyst culture is a good idea.
Are there any drawbacks of blastocyst culture?
For extended culture it is imperative that embryology lab conditions are strictly maintained. Also there is 1-2 percent risk of no blast forming in a cycle which should be taken into account
For any further queries please consult Dr Prerna Gupta to discuss the best fertility option for you.