slow freeze vs. vitrification

It was my understanding that vitrification of embryos was better than the "older" slow freeze method. In talking with my RE(and I may have misunderstood him) he had mentioned that vitrification was "harder" on compacted morulas than the older slow freeze method would be. I was a little confused by this. He did mention that they no longer freeze morulas at their clinic only blasts. He gave my morulas a 70% chance of surviving the thaw. I was wondering if you could help explain this to me why in some cases the slow freeze may be better for some stage of embryos(if this is even the case?) Thanks for and information you can give me.

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Originally Posted by ShapeOfMyHeart

It was my understanding that vitrification of embryos was better than the "older" slow freeze method. In talking with my RE(and I may have misunderstood him) he had mentioned that vitrification was "harder" on compacted morulas than the older slow freeze method would be. I was a little confused by this. He did mention that they no longer freeze morulas at their clinic only blasts. He gave my morulas a 70% chance of surviving the thaw. I was wondering if you could help explain this to me why in some cases the slow freeze may be better for some stage of embryos(if this is even the case?) Thanks for and information you can give me.

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Hi Shape of my heart,
I would venture to say that your doctor's experience is not universal but since he has indicated that their own lab results are poor for vitrification of morulas, probably best to let them do what they can do. In my own lab, we found that any stage vitrified well, except for expanded blastocysts that needed to be manually deflated with an ICSI needle first to get good results. Vitrification requires excellent technical timing and handling which is a learned skill. Some labs are better at it than others. Good Luck. Carole