# Freezing embryos



## Aich (Apr 29, 2002)

Hi Peter,

I wondered if you could shed some light please. I had 5 day blastacyst transfer in May, and five were put on ice. Unfortunately I got a positive pg which ended in a m/c. Anyway, we are in the process of having FET. Was a bit put out to say the least, when at my review, the clinic advised that blasts did not freeze as well as day 2/3 embyos. I would always have gone to blast in view of the success rates, but was miffed that the freezing/thaw success rates were not so good. I had to get that out of them via direct questioning, hence this information was not volunteered when we made our original decisions.
My question I guess, is why is it they they have a worse record? Also, roughly how much worse

Thanks for your help.

Helen


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## peter (Oct 2, 2002)

Dear Helen,

In the early days of IVF all embryos were allowed to get to blastocyst stage before freezing on the basis that these were the best embryos to freeze. The freezing technology for blastocysts is therefore well established. Having said this the majority of clinics now freeze earlier cleavage stage embryos which tends to result in the embryologists not being very experienced in blastocyst freezing and thawing.

Blastocysts do have a slightly lower thaw rate than earlier embryos even in expert hands. This is because the blastocyst needs to re-expand on thawing, a process over which we have no control. I have done lots of blastocyst freezing during my time at Bourn Hall and at that time we would get approximtaely 70% of the frozen blastocysts successfully thawed. Some clinics today may achieve better rates than this, others may achieve significantly less.

If you are really concerned I would ask your embryologist about his experience of blastocyst thawing and if there appears to be a lack of experience you could consider transferring your embryos to a clinic where they are very experienced in blastocyst work.

Hope this helps!

Peter



Aich said:


> Hi Peter,
> 
> I wondered if you could shed some light please. I had 5 day blastacyst transfer in May, and five were put on ice. Unfortunately I got a positive pg which ended in a m/c. Anyway, we are in the process of having FET. Was a bit put out to say the least, when at my review, the clinic advised that blasts did not freeze as well as day 2/3 embyos. I would always have gone to blast in view of the success rates, but was miffed that the freezing/thaw success rates were not so good. I had to get that out of them via direct questioning, hence this information was not volunteered when we made our original decisions.
> My question I guess, is why is it they they have a worse record? Also, roughly how much worse
> ...


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## Aich (Apr 29, 2002)

Peter,

Thank you for taking the time to reply. I am likely to have my transfer next week!!!. However, my clinic advertise that you can speak to the embyologist, and he always rang on my fresh collection on a daily basis. I am going to call tomorrow. I am sure that they have done blastacyst for a while, so am hoping that they are experienced.

Thanks once again

Helen


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