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In laboratories that routinely freeze embryos at the blastocyst stage, they survive the thaw well. Assisted hatching can easily be performed on frozen-thawed blastocysts, as the embryo is retracted from the protein coat at the time of the thaw. Performing AH on frozen-thawed blastocysts is not rocket science. We routinely perform AH on frozen-thawed blastocysts in my laboratory.

Hi Dr. Smith,

I had a phone consultation with a doctor at CCRM today, and he told me that in their lab about 60% of frozen embryos survive the thaw. That figure surprised me, since I had gathered, I think from things you said, that the survival rate for frozen and thawed embros was much higher than that. Did I misunderstand somewhere along the way? Or maybe I am not correct in thinking that CCRM has one of the most successful programs going. (But looking at the CDC ART reports, they sure seem to do a lot of IVFs and with very good success--much higher than the national averages.)

Thanks.

Freezing and thawing blastocyst stage embryos can be tricky. That's why I qualified my reply to your post by saying "laboratories that routinely freeze embryos at the blastocyst stage". I don't know what method CCRM is using for blastocyst freezing or how often they freeze blastocysts. Both of these factors could contribute to a 60% survival rate. Also, make sure they were talking about survival of blastocysts, not Day 3 embryos or embryos overall. On the up side, CCRM has a good term delivery rate for frozen-thawed embryos. So the embryos that do survive have good developmental potential.

A word about interpretation of pregnancy rates:

Although CCRM has a relatively high pregnancy rate (higher than the national average), they achieve this by transferring around 3 embryos. This results in an unacceptable level of high order multiple gestations (triplets and higher) in all age categories (up to 10% of their pregnancies are triplets and higher). Triplets, quads etc. are frowned upon in the IVF community as they are high risk pregnancies that endanger the babies and the mom. Triplets are always born very prematurely and can have multiple long term health problems assocoated with pre-term delivery. Read between the lines. Because pregnancy rates are an "all or none" end point, they can be misleading.

I spoke with the doc about the fact that they tend to transfer more embryos, and have issues with higher order multiples. Their stats for more recent years (not yet filed with the CDC) are much better on this score. In the group I'm interested in they now transfer an average of 2.1 embryos.

Thanks as always for your thoughts.

Glad to hear that they have backed off on the number of embryos they transfer. Its better all around.