What Stage is best(if any) for freezing an embryo

[nuthinbutpink]

Hi Dr Wegner.

I am asking for our members-

Many of us are opting for day 5 biopsies and embryos generally need to be blastocysts in order to have a day 5 biopsy. Do you think it matters what stage an embryo is frozen in regards to surviving a thaw?

Meaning, early blast versus expanded, hatching or fully hatched- is there a reason to want to freeze before an embryo completely hatches from its shell or is any blast stage fine for freeze(assuming vitrification is used).

Thank you!

[Carole]

Hi Dr Wegner.

I am asking for our members-

Many of us are opting for day 5 biopsies and embryos generally need to be blastocysts in order to have a day 5 biopsy. Do you think it matters what stage an embryo is frozen in regards to surviving a thaw?

Meaning, early blast versus expanded, hatching or fully hatched- is there a reason to want to freeze before an embryo completely hatches from its shell or is any blast stage fine for freeze(assuming vitrification is used).

Thank you!

Dear NuthinbutPink,

I wrote a post on this topic previously Fertility Lab Insider - Lessons learned from over fifteen years of working inside fertility labs. » Blog Archive » New Series: Q From U: biopsy where I looked at biopsy on day 5 vs day 6 and whether it is a good idea to wait for spontaneous hatching prior to biopsy.

Vitrification does very well at any stage. The only caveat is that for fully expanded blastocysts (straining at the shell but not yet breached), it is important to artificially collapse the blastocyst using either a laser or mechanical means. Collapsing the blastocyst allows full penetration of the cryopreservative solutions. If the blastocyst is early stage (not fully expanded) or has collapsed on its own or has hatched (even slightly) the solutions are able to penetrate just fine, so not extra intervention to collapse is needed.

In any group of embryos, there will likely be some at each blast stage so the technologist should be able to collapse the blast when needed prior to vitrification--or alternatively pull an embryo part way out of the shell to grab a piece for biopsy if it isn't spontaneously hatching in the timeframe for PGD. Hope this helps! Carole

[nuthinbutpink]

So a fully hatched blast should freeze and thaw fine? There's no risk when its hatched from the shell completely?

[nuthinbutpink]

That is a great post! I missed that one. SART in Thailand is affiliated with Genea(Sidney IVF). GS is illegal in Australia but they can go to Thailand for treatment. They require hatching blasts in order to do a biopsy. That's their policy. Based on your post, I suspect people will be cautious when choosing a clinic that is that strict for biopsy.

[Carole]

So a fully hatched blast should freeze and thaw fine? There's no risk when its hatched from the shell completely?

We would like to have a shell on it--for our own peace of mind-but we have had no obvious problems getting pregnancies from hatched thawed blasts.

[Lara22]

So glad I have read this great post, it's really helped with my decision process on what to do next!