The embryos that can become transferred on IVF ET day are mainly determined based on the morphological scoring of the embryos. The scoring of embryos at the cleavage stage is mainly based on the number of cells, size, symmetry and proportion of surrounding debris of the embryos, etc. Usually we score the embryos based on the third day after egg retrieval and select the best 2 embryos for transfer and freeze the remaining good embryos. The remaining good embryos will be frozen. The bad embryos will be discarded, if your embryos are between good and bad, we will perform blastocyst culture and if they form blastocysts they will continue to be frozen, otherwise they will be discarded. Blastocyst culture is a greater test for the embryo and can screen out some of the embryos with good potential. So the embryos that do form into blastocysts are of good quality.