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Why You Should Be Skeptical About New PGT-A Testing Methods

Dr. Gleicher discusses the introduction of a new preimplantation genetic testing for aneuploidy (PGT-A/PGS) method that uses cell-free DNA. Not all forms of genetic embryo testing are right for everyone.

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Hello, I want to talk to you about one of my favorite topics, PGTA (pre-implantation genetic testing for aneuploidy-- until recently called PGS or pre-implantation genetic screening). If you have been watching our videos, if you have been reading our newsletter, you know that we here at CHR are anything but fans of this test or procedure, whatever you want to call it. Indeed, we think it's useless and for some patients a harmful test or procedure (especially in all the patients and women who have just few embryos it will actually significantly reduce pregnancy and life birth chances). The only reason why I'm coming back to this topic which we have addressed so many times over and over again and have written so much about also in the medical literature is because a funny thing has been happening. And that funny thing is that one of the more prominent IVF centers in the country just recently informed the public that they now were offering yet another form of PGTA, which this time does not require an embryo biopsy in order to determine whether the embryo is chromosomally normal or not. Up until now, in all of its three incarnations over 20 years, the procedure required such a biopsy. During the first incarnation, we used to biopsy embryos at cleavage stage-- 6 to 8 cell embryos, then we switched to blastocyst stage and that is still the standard method being used. We are biopsying the trophectoderm of the embryo, getting 5-6 cells and they are supposed to tell us whether the embryos chromosomally normal or not. Now comes this "revolutionary new technique" announced, which claims that they can do the same thing by testing the spent media in which an embryo was cultured. The spent media is the fluid in which an embryo is cultured. And they're claiming that on the basis that there is something that is called "cell-free DNA," which is now widely used through blood testing whether for early prenatal diagnosis, whether for cancer diagnosis, and other potential diagnostic tests, but it has never been used for diagnosing anything from the spent media of a culture. Now, before this center announced the commercial availability of this now "non-traumatic" new tests, others have tried to do this, but their accuracy was so low that every one of those two or three studies that have been published on this subject very clearly claimed that this is not yet ready for primetime, that this kind of technology cannot be used. Yet, here we go again. And one of the more prominent IVF centers in the country announces a commercially available test that has never been published, so nobody knows any details. Nobody knows whether, and if so how, it has been validated. Nobody knows how accurate it is, in other words how high its predictive value is, what its false positive rate is, what its false negatives are, and yet it's again commercially offered. And this is simply mind-blowing to us. We call this PGTA 4.0, or PGS 4.0. And as a joke we quite a while ago already predicted that this would happen with PGTA 3.0, having gotten into a lot of trouble once ASRM recently once again published a statement and that this test has not yet established any efficacy in IVF practice. So whenever the current market is threatened, the genetic laboratory testing community comes up with the next big invention and never ever are we told why and what these testing arounds can really tell us about embryos. One final point-- in the end, how accurate this new form of embryo testing is at blastocyst stage, it really doesn't matter. It doesn't matter because the embryo at that stage can still to a large degree self-correct. And even assuming that the test results are normal (and we don't know that), but even assuming that the test results suggest that that embryo at blastocyst stage has aneuploid cells (has chromosomally abnormal cells), that embryo over the ensuing days still in a high percentage of cases will self-correct. So why test at earlier stages? Thank you for listening.

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