What are the grades of embryos for IVF?

The grading for the blastocyst are al follow: we have numbers between 1 and 6 and 1 is mainly starting blastulate so we can’t see better the inner cell mass and the body of the trophectoderm and then 2 more expanded, 3 is full expanded, 4 more expanded, 5 start to hatch and then 6 is fully hatching in this case. Then there are the scores of the inner cell mass and trophoderm between A and D; A means that it’s top rate and D is the worst embryo, not suitable for freeze or transfer in this case.

There are different grading systems and different stages of embryo development. Although national consensus seems to exist in some countries like Spain and UK these are quite few.
Embryo grading system assesses the growth of the embryo based on specific criteria. It is a morphological assessment of the embryo, at different stages of development. Nowadays, we have time-lapse technology as well. They use advanced software algorithms that do the calculations for us if you like, such as what embryos to select for the embryo transfer. Simply a pre-compaction embryo on Day 2 or Day 3 of the embryo development, the embryoscope or the embryologist assesses for the number of the cells that the embryo has, how regular the cells look, if there are any signs of fragmentation. Moving on as the embryo keeps growing quite fast at the blastocyst stage, the grading system is slightly different. At this stage we cannot assess the number of cells, we assess the presence of two different cell types: one is the inner cell mass – the group of cells that would make the baby and the trophectoderm cells that will make the placenta. Most labs assess on day 5 embryos as A, B or C with A and B being the highest quality embryos and C- the lowest quality embryos. Usually you will hear the number before that, for example, 5AA is an expanding hatching embryo with grade A trophectoderm cells and grade A inner cell mass cells.