Sunday, 6 July 2014
Grading of embryos
The embryos are graded morphologically - the way they look under the microscope. The grading of embryos is done in order to identify the embryos with the best potential to implant and lead to a pregnancy. But please remember, it is only an indication, we all see embryos of the best grade failing to lead to a pregnancy while lower quality embryos can also grow into a pregnancy.
The ideal embryo at the Day 2-3 stage should have blastomeres (cells of embryos) that are uniform in size and should have no fragments or leaked out contents of the cell during the division process. The ideal cell number on the second day of embryo's life (two days after the egg collection) is 4-cells while the cell number should be as close to 8 cells on the day 3 stage. Embryos that are slower or faster are marked down as are embryos that have unequal blastomeres or fragmentation.
It is also important to realise that the grade has no bearing on the normality of the embryo formed. In other words, the best grade embryo may be chromosomally abnormal and a poor grade embryo may be normal. Different labs use different grading systems and so please ask your lab to explain what their grading system is.