Freezing Blasts
3 Replies
jennt - January 3

My RE says that they cannot freeze Blasts, even from a fresh cycle. I have read about so many girls who have Blasts in cryo from previous IVF cycles. I have 10, 3 day embryos in cryo and my RE will thaw all of them in hopes to get 2 blasts for my next FET cycle. What if more than 2 go to Blast, I would want to refreeze them for a future cycle. Is this possible?

Thank you very much for your time.



Dr Smith - January 8

The re-freezing of frozen-thawed Day 3 embryos that reach blastocyst stage has been achieved, but is not recommended. The survival rate of these blastocysts is relatively poor. It is much more likely that, if you are fortunate enough to have more than two blastocysts after the thaw, your RE will suggest transferring them. This makes sense because the implantation potential of these blastocysts is reduced.


jennt - January 8

What about culturing embryos to blast and then freezing them originally, not re-freezing. My RE will not freeze blasts, period. Why do you think? I want to do another fresh cycle but I want the lab to take my embryos to blast rather than 3 day, transfer a couple and freeze the rest. I had a problem with embryo quality that did not show up until after the 3 day point so I do not want to transfer anything but blasts in the furture.


Dr Smith - January 10

Some programs have struggled with culturing embryos to the blastocyst stage as well as freezing embryos at the blastocyst stage. So, it may be one, the other, or both that makes your RE reluctant to try.

I think your strategy is a good one. First, you have to find a program that routinely cultures embryos the blastocyst stage and has a good freeze-thaw record with blastocysts. Be aware that some programs will start out with the intention of culturing the embryos to the blastocyst stage and then "bail out" and do a Day 3 transfer if the embryos don't look like they're going to make it. Make sure you are clear from the beginning that, no matter what, you want to continue to the blastocyst stage.

Best of luck and I hope that you are successful.



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