# QUESTIONS ON EMBRYO CRYOPRESERVATION PROCESS



## nettar67 (Jan 13, 2010)

Hi,

Can someone please answer me the following questions:-

Can embryos get damaged after they have been thawed?

What is the percentage of embryos being damaged after they have been thawed?

Is it possible for embryos to be damaged in the embryo cryopreservation process?

How many times can the same embryos be frozen and thawed?

Thank you for taking time to read my questions and I look forward to getting some answers.


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## Ellie.st (Mar 11, 2005)

Dear Nettar67

I'm not an expert in any way but here is what I understand about freezing/thawing embryos.

1.  On average, about 65% of frozen embryos thaw successfully.
2.  It is quite normal for frozen embryos to lose some cells during the thaw - if this happens, they can start re-dividing and make up for the cells they have lost.  This happened with one of my frozen embryos which went down from 4 cells to 3 cells when thawed, but was showing signs of dividing at transfer time.  On the same FET cycle, I had another 6/7 cell embryo which went down to 2 cells when thawed, and a third 6/7 cell which went down to one cell when thawed - neither of these were showing any signs of dividing when they were transferred.  I had all three put back and am currently 29 weeks pregnant from that FET cycle - two of the three embryos implanted and were seen with heartbeats at my six week scan although one had unfortunately vanished by week nine. I think it is the 3-cell embryo rather than the 2-cell one which survived but have no way of knowing for sure.

I've never heard of embryos being frozen and thawed more than once, but maybe someone else knows more than me...

As far as I am aware, there is no evidence of babies born as a result of frozen embryos suffering any adverse effects, although FET does have a lower success rate than fresh IVF cycles (possibly because it is often lower-grade embryos which are frozen after fresh cycles - ie the best ones are replaced in the fresh cycle).

Hope this helps a bit.

Ellie


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## livity k (May 19, 2009)

Hi 
Just to add- a lot of clinics are now moving to use vitrification to freeze embies and this leads to a higher defrost rate- 90%. 

I had five blastocysts frozen and  all successfully defrosted for 3 FET's they all lost some quality but were still good quality- I think the reason the first four didn't work was to do with my immunes not the frosties! 

i think the damage if it does occur happens when the liquid is removed and put back in the embie during the process of freezing and thawing, vitrification is much faster than traditional methods so causes less damage,

Livity


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## nettar67 (Jan 13, 2010)

Hi

Thank you both for your help and replies, and congratulations to you Ellen on your pregnancy.  May I ask which clinic you went to for the embryo transfer and were they your own eggs or a donor?

Thanx

Netta


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## Ellie.st (Mar 11, 2005)

Hi Nettar

The frozen embryos were from my own eggs.  I had my treatment at Aberdeen ARU.

Ellie


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