Not all embryos are capable of surviving the processes of freezing and thawing. The best quality embryos have higher survival rates, so it is preferable to freeze those of quality A and B, although it is also possible to freeze those of type C. However, if the couple does not have better quality embryos, even type D embryos can be frozen, but this is not done in all centers because of their low survival chances. In most cases what is done with poor quality embryos is to leave them until day 5-6 in culture (under "observation") to see how they evolve.
What quality does an embryo have to have in order to be frozen?
By Zaira Salvador B.Sc., M.Sc. (embryologist).
Last Update: 08/08/2018
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI)