# Do Blastocysts defrost Ok?



## Fee

Peter,
We're off on the coster again ! I'm having a natural FET with my ONE blastocyst. Plus simultateous IUI to give us the best possible chance.
Someone recently posted that blasts were less likely to defrost OK. I thought Blastocysts were naturally selected stronger embryos? Why would their chances of successful defrosting be less?
Fee


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## Mummytoone

HI Fee

Im watching this space!

Love Lou xxxx


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## LadyP

My understanding is that with more cells the process where the water is replaced with 'antifreeze' (and the reverse during the thaw) becomes more complicated and so there are more likelihood of problems during the whole process. Obviously the more experience with blasts the better.

Maybe these quotes will help:

"Blastocysts (embryos cultured for 5 days rather than 2-3) are a special case. The embryos are much larger and have special needs with regard to freezing without damage. Many centers have had trouble with blastocyst cryo-survival and pregnancy rates. "

"Another disadvantage of Blastocyst culture is the poor success rates associated with blastocyst cryopreservation. Some clinics have reported results of blastocyst freezing with resultant clinical pregnancy rates of up to 30%. However, most units worldwide have reported results much lower than this (less than 10%), which is probably a more realistic figure. Certainly, one of the biggest dependent variables in this situation is the quality and number of blastocysts available for cryopreservation "

"Embryo survival rates after thawing and pregnancy rates in most IVF programs are highest for embryos that were frozen at the pronuclear stage, or at the 2-cell to 4-cell stage."

Check the stats for your hospital and see what their FET success % is. 


Good luck!


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## peter

fee said:


> Peter,
> We're off on the coster again ! I'm having a natural FET with my ONE blastocyst. Plus simultateous IUI to give us the best possible chance.
> Someone recently posted that blasts were less likely to defrost OK. I thought Blastocysts were naturally selected stronger embryos? Why would their chances of successful defrosting be less?
> Fee


As with all blastocyst work it is only worth doing if the clinic has a longstanding experience in blastocyst work, preferably doing blastocyst only transfers and freezing. If this is not the case I would go for cleavage embryos as success rates are poor for blastocysts with the inexperienced clinics.

Goos luck!

Peter


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## Suzek

Dear Fee

Just to let you know that I recently underwent FET with blastocysts. I am really pleased to be able to tell you that we had 100% thaw success rate with 2 blastocysts, however, unfortunately they did not go on to make me pregnant. I too was extremely concerned regarding the thawing rate so when we were told 100% success I guess we really built up our hopes for a positive.

I wish you loads of luck with your thawing and hopefully, ongoing pregnancy!

love

Suzek


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