By fertility experts from Spain.
In this webinar, Dr Luca Gianaroli, MD, Scientific Director of S.I.S.Me.R (Italian Society for the Study of Reproductive Medicine) has explained PGT-SR, preimplantation genetic testing for chromosomal structural rearrangements, how it’s done, indications and how it can improve the chance of a healthy pregnancy.
No, even if there is a variability that’s changed from patient to patients. The survival rate and the viability rate of frozen-thawed embryos after biopsy vary between 98 to 100% of viability. The risk of losing the embryo is extremely limited, as far as the right technique is used and, in this case, the vitrification technique.
Not fertilization because most of the time, when you’re using ICSI, you just force fertilization. The problem is that in some translocations, these embryos have not enough energy. If they are generated by unbalanced gametes, they don’t have enough resources to normally develop. These embryos do not develop properly. So, no for fertilization, potentially yes for their development.
For a very simple reason because you know in advance that a percentage of these eggs that even if they fertilize or even if they develop an embryo, they will not be transferable. You need more eggs to have more embryos to choose from a larger basket of embryos, those that will be suitable for transfer.
All in all, it’s quite a complicated question because it depends on the type of mosaicism, it depends on the percentage of mosaicism. What is interesting is that if you use some technique, you don’t see the mosaicism, you only see if they are euploid or aneuploid, they are black and white.
If you use more sophisticated techniques, then you can see mosaicism. Then there is a sort of degree of risk that you can take in transferring embryos that are mosaic according to their percentage and chromosomes that are involved.
It depends on what you mean by failure. If you mean no embryo development, so no embryo transfer, I would not go for it if you are a poor responder over two cycles. If you are a poor responder, you can also wait for a third cycle. If by the failure you mean a biochemical pregnancy or a miscarriage, then you don’t need to stop IVF but to go for PGT for an aneuploidy, of course, this implies first perform the chromosomal analysis in both partners.