Q from U: Growth potential of frozen vs. fresh embryos

Hi Victoria,

You asked me:  Do previously cryopreserved embryos develop similarly to fresh embryos so that, if one is attempting an e-SET, growing them out is one way to determine the ‘best’ one or are they somehow more fragile?

How well thawed embryos grow out depend on several factors:

  • method of freezing and thawing (Vitrification has the potential to completely preserve the integrity of the cells meaning no cells die, if performed properly compared to slow freeze protocols in which some loss of cell viability is expected)
  • How well method was performed (Even vitrification, if done poorly, can kill some or all of the cells)
  • Both the freezing and the thawing (thawing is termed  “warming” for vit) must be done expertly. A botched freeze can’t be saved by a perfect thaw  and vice versa.
  • The culture method employed by the clinic (can they routinely grow fresh embryos to blastocyst stage- or is this problematic for them?- do they mostly transfer on day 3?), If day 5 culture is one of their strengths, go with it.
  • Intrinsic properties of the embryo (genetic or metabolic) which determine if it will continue or die

If all these factors are in your favor, it is perfectly reasonable to grow thawed embryos out in culture to see which ones can make it to blastocyst stage because these are most likely to implant. Frozen embryos shouldn’t really be more fragile once they have recovered from the freeze/thaw process. The only other alternative is to thaw one for eSET and hope for the best (that it will progress appropriately and be transferred) which is more risky than thawing several and growing them out to select for one “best”.  Good luck for a positive pregnancy!!

Related posts:

Embryo stages, progression and pregnancy outcomes

Day 3 vs. Day 5 culture

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©2012 Fertility Lab Insider. All Rights Reserved.



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