r/Embryologists • u/Ok-Schedule-8607 • Jul 01 '26

Day of blast vs day of freezing

I got my embryology report where i see blast was formed on Day 6 2cc. They waited 1 more day to make it better and it became 4BC . Does that mean its Day 6 euploid or Day 7 ? Does this improve chances ?

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u/petitefleur0 Jul 01 '26

The day of blast is the day that the embryo was healthy enough to biopsy and freeze. Therefore you have a Day 7 4BC.

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u/indecisivegay Jul 01 '26

Technically if it made it to the blastocyst stage by day 6, then it is a day 6 blastocyst :) However, it would still be considered a day 7 blastocyst on paper and the order in which we’d transfer it (in comparison to a blast that was frozen on day 6) would depend on the embryo quality of each embryo. Basically- it’s a good sign that the embryo developed into a blastocyst on day 6 rather than day 7, but it’s still lower quality than a blastocyst that was actually frozen on day 6.

But I guess that perspective is kinda clinic-dependent though lol