Embryos frozen on day 6 and 7

Hi Carole-

I have two frozen embryos from my last cycle, both hatching blasts, one frozen on day 6 and one on day 7. Both embryos are XX and characterized as normal euploid by day-3 CGH. The day-6 is graded as B/A/A and the day-7 is graded as B/B/B (where A=best, C=worst, and the three grades are inner cell mass/outer cell mass/fluid-filled cavity).

My RE has given me an estimated success rate of 40-50% with each one in an SET. However I have been looking around at research and I have seen some studies claim that embryos frozen after day 5 do not fare as well. I am concerned that he may be overestimating my odds, in particular for the day-7 embryo. If I do an SET with the day-6 embryo that fails, I don't want to be going in with poor odds on another SET with the day-7.

I saw your other post regarding vitrification and to be honest I am not sure what technique my lab is using, but I would assume they are using the latest method as their FET success rate for age<35 is 53%. I will confirm this on Friday, and will also ask my RE if they have had success with day-7 embryos. But I am very interested to hear your thoughts on this also. Thank you so much!

Gently bumping in case this was missed!

I can only address this from my own experience. In our program, we saw the best results with day 5 blastocysts. Day 6 blastocysts were less common and we had fewer pregnancies with them overall and as a percentage of transferred embryos. We did not grow out to day 7 because they either reached blast stage or stopped developing on day 6. But the real issue is how does your doctor do with these day 7 embryos? My guess would be that like us, most embryos got to blast earlier and so he has less data for slower growing embryos but hopefully he has been tracking those outcomes. You really need to ask him about day 7 results. Best Wishes, Carole

Thanks Carole - I did talk to him after posting this and he said they have seen success with Day 7 embryos but gave it a 30% chance. Still too high for me to put both back and risk twins. My day 6 embryo was fertilized with ICSI, but the day 7 was fertilized with IVF, so maybe it fertilized later?

Jacqueline,
I can't tell whether the day 7 embryo was fertilized later. If these embryos came from two different IVF cycles, one ICSI and one regular insemination, I suppose the natural fertilization could have been one day later, but not likely two days. It just sounds like really slow progression. Usually, an IVF case is either ICSI or regular insem. There are two situations where you might see both in one cycle- split cycles and rescue ICSI. Split cycles are sometimes done when the doc wants to test whether ICSI is necessary. Rescue ICSI is done the day of a failed fert with insem if there is no evidence of sperm binding to the egg.
Best Wishes,
Carole

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8 of my eggs were done ICSI and 8 regular IVF. I believe they split them because several of the eggs did not appear quite mature enough to be stripped for ICSI. I had 7 fertilize from each group (maybe you remember, I had posted a different question to you a month ago about it). Of course the fertilization was not two days later, because everything was checked on day 1 and it was 2PN at that point. Thank you for your comments!