Blastocyst Grade - Freeze/thaw survival and chance of implantation
6 Replies
cb38 - January 5

I would appreciate your insight...
I'm doing an FET cycle and will be transferring (hopefully) two or more blastocysts. The grades are quite different so I'm wondering what the chance of surviving the freeze/thaw is and what my chance of successful pregnancy is. It's like pulling teeth to get info out of my RE...

Blastocyst grades are:
#1 5AB (on day 3 it was 8 cells no fragmentation)
#2 5BC (on day 3 it was 14 cells 10-25% fragmentation)
#3 5CC (on day 3 it was 8 cells > 25% fragmentation)
#4 5BB (on day 3 it was 8 cells 10-25% fragmentation)
All are PGD normal for 9 chromosomes

Does the grade of the trophectoderm impact implantion potential? Or is the inner cell mass grade much more important?
Also, how many do you think I should transfer?

Little bit of history...just turned 39, one natural pregnancy back in March but miscarriage (trisomy 18) at 13 weeks, 1st IVF cycle BFN. FSH level is fine. Lining is good (9+). Responded extremely well to stimulation.

Thank you!


Dr Smith - January 8

The inner cell mass (first letter in the grading scheme) is more important that the trophectoderm (second letter). Trophectoderm grows like a weed. However, a poorer grade inner cell mass (which contains the stems cells) may not be adequate to develop into a baby.

I don't think the 5CC is going to survive the thaw. The 5BC and the 5BB are a bit "iffy". The 5AB looks good. Depending on what survives the thaw, I would recommend transferring the best 3.


cb38 - January 9

So a blastocyst with ICM graded B or C has poor implantation potential if they survive the thaw?

What is typically the % chance that a grade grade A will implant?


Dr Smith - January 10

Yes, the B and C grade have a significantly decreased chance of producing a healthy pregnancy. Embryos with an inadequate number of stem cells may result in a chemical pregnancy or an "empty sac".

About a 20% implantation rate, but the term pregnancy rate will be about 15%.


cb38 - February 1

Thank you so much for the information you provide! I love reading your responses, seems like its the only place to get real, straight-forward info.

The freeze-thaw and transfer went great. We thawed two (the 5AB and the 5BC), both survived and the embryologist rated their survival of the thaw as "very good" and said both were hatching. My RE didnt want to transfer three because these two did so well, thought it might be too overly aggressive and risk triplets.

My lining looked great, 9+. Does the fact that they were hatching at time of transfer mean they have a better chance of implantation? Our chances now?

I guess I'm trying to stay as hopeful as possible... :)


2dFertProb - March 27

I have a 6CB blast and 4CB blast both frozen. What are my chances that either will result in a healthy pregnancy?


Stardust - May 5

I did my first cycle of IVF in April 2013 and did not transfer any embryo's due to mild OHSS and only 2 embryo's made it to blast at day 5. will be doing a FET in June I have a 3AB blast and 4BA blast both frozen what are my chances of result in pregnancy.



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