Rate and Criteria for Freezing Blastocysts


I was looking for information on how often a clinic is able to freeze blastocysts. As per a doctor at our last clinic, in about 50% of the total cycles they perform, there are no blastocysts which can be frozen. This is because either none of the embryos develop to blastocyst stage, or those that do become blastocysts are of poor quality and hence not good enough to freeze.

Out of our 3 cycles with them, they only managed to freeze 2 blastocysts from our first cycle. In our last meeting with them, they indicated that our embryos had developed to blastocysts on our other cycles also, but they were not frozen because they were judged to be of poor quality.

I was wondering whether 50% of cycles with nothing to freeze is the average rate for all clinics and what standards are used to judge whether a blastocyst is worth freezing or not.

Thank you for any replies!


This always bothers me. I know most places will say that there was nothing good enough to freeze on most cycles. So, I think the rate your clinic quoted you is probably good. But, I wonder. Why don’t they freeze the best ones and put back the second best as a fresh transfer. A lot of those “too poor quality to freeze” would still make babies. So why not freeze the best ones and give everyone as many chances as possible?


I specifically asked to put in lower quality blasts (if there were any) in order to have as many chances as possible. It didn’t happen because we did a day 3 transfer (we only had 5 fertilize) and my clinic did not like the idea. They want their SART scores to be as high as possible, so they want to transfer the best. I did get my clinic to agree to freeze all that make it to blast instead of just “good or excellent” quality ones.


Don’t allow weaker ones to be discarded. There are many cases where excellent ones didnt succeed but the weaker ones. Had you been testing them for genetic disorders, would have been different but to throw them only because they don’t look good is not a good reason. Also, since you had many mcs, do some investigations. I dont think you are dealing with the embryo issues here. Gl in any case!


Cosmopolitan, Unjour & Xerxella: Thank you so much for your replies. I actually had no idea that they were doing this. I always assumed when they told me that no embryos had been frozen, it was because none made it to blastocyst stage. I only found out at our last appointment (we have finished all our cycles at this clinic) when I asked if there was an issue with my egg quality and the doctor replied that there probably was no problem with my eggs since we had been getting blastocysts, even though in some cases “they were not considered good enough to freeze”!


I just found out the grades of my blastocysts which were not frozen: 4 blasts of grade 4CC 1 blast of grade 3CC 2 blasts of grade 5CC 1 blast of grade 5BC Shouldn’t at least some of these have been frozen - at least the 5BC? Could someone let me know the cutoffs in their clinic?


@unjour, it’s actually not a bad idea to transfer some marginal ones fresh, and freeze the strong ones. For this cycle, I was willing to transfer two, but only if there was a clear best embryo, and the second one is worse. It so happened that all three embryos were pretty good on day 3, so I transfered just one. I can’t believe they would not transfer the embryo of your choice - you own them, after all. I will be getting my freeze or bust report tomorrow, and will ask the embryologist which grades they freeze. In 2010, they froze two blasts, and quite honestly should have only frozen one. The second one was an early morula on day 5 (i.e. marginal), and though it made to the blast, it did not even survive thawing. So, I am not sure I believe in the ‘freeze all’ approach.


I also wonder about this. We have only done one cycle of IVF, back in April. I had 10 eggs retrieved, and all 10 fertilized. 8 of them were growing strong on day 3, and we had them transfer the best one (3AB) on day 5. There was also an early blast at that point. On day 6, the early blast was a 4CC. I think there were 3 others that were 2s (my clinic doesn’t grade 2…that’s an “early blast”). All were discarded. While I am extremely grateful for the BFP we got from our blast (I’ll be 35 weeks on Friday), I also know if we want future children, we will have to do this all over again. It just seems so weird that so many were doing GREAT at day 3, and then didn’t even make the cut on day 6. I truly believe that some of those would’ve been fine as a fresh cycle, but maybe wouldn’t survive the thaw? It’s very frustrating. For the record, my clinic also told me that less than 50% of IVF patients have eggs to freeze. That made me feel a little better, but was surprising.


My embies did not make it, but I talked to the embryologist today. She said that they grade brastocysts into 1, 2, and 3s, and 3s don’t have the cellular structure to continue on, so they would not freeze them.


My clinic must grade differently than some. 1 is early blast, 2 is (developing?) blast, 3 is full blast, 4 is expanded blast. They only normally freeze “good” or “excellent” expanded blasts. We ended up having one good and one excellent expanded frozen as well as a good full blast frozen. That one was compacting on day 4 and a morula on day 5, but did make it to blast.


wantbabiesnow - Have you gone for additional testing, re your history and m/c’s? I do wonder if your issue is not embryo quality.