Should we forget about embryos till day 5?

PURPOSE OF REVIEW: To find the way of having more and better blastocyst is essential. How to culture embryos up to blastocyst stage remains critical.

RECENT FINDINGS: Several studies show how a blastocyst score can predict the implantation potential. If that score is enough to choose the best blastocyst, as culture conditions would not be affected in these days, we would not need to check early cleavage embryos, even it could be better for the embryo development.

SUMMARY: The item that should be discussed is if it is better to evaluate or not embryos at early cleavage stages. If we do not check embryos on days 2 and 3, we should change our way to work and how to culture those embryos. First step would be to perform all embryo transfers on day 5 or 6. If we let embryos grow to blastocyst without any morphology evaluation, we should adapt several steps in our laboratory, for example we should move to a single-step culture medium or we should not do assisted hatching on day 3 embryos.