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Preimplantation Genetic Screening (PGS) and Frozen-Thawed Embryo Transfer (FET)
Our clinic performs Preimplantation Genetic Screening (PGS) with Frozen-Thawed Embryo Transfer (FET) on almost all of our stimulated IVF patients.
PGS and FET are two exciting and promising technologies now readily available and they are tranforming the way we now perform stimulated IVF with far better outcomes too. Herein, I describe these technologies and I will show you how we may get better outcomes for our patients when we utilize both PGS and FET.
My first patient that I will describe for you is a healthy 32 year- old woman who has one child spontaneously conceived and delivered in 2011. The couple then experienced over 3 years of secondary infertility. Her medical evaluation was normal but her husband had problems with his sperm morphology requiring treatment with IVF. They initially chose Natural Cycle IVF (NCIVF) (Dominion Fertility is the largest NCIVF program in the United States) but no egg was obtained in their first treatment and no fertilization occurred in her second treatment, so stimulated IVF was recommended.
Using stimulated IVF, we obtained 21 ova and 8 blastocyst embryos were produced. PGS was performed on all of her embryos and all were cryopreserved and stored. Of the 8, only one embryo was genetically normal. However, one month later, this one genetically normal embryo was transferred in the patients’ normal natural cycle (Natural Cycle-Frozen Embryo Transfer) resulting in a normal appearing viable pregnancy. The patient has been referred to her Obstetrician for routine care. Earlier this year, I had a 28 year- old patient who also produced 8 blastocysts embryos, again producing only one genetically normal embryo discovered using PGS. She too became successfully pregnant using NCFET in her first embryo transfer.
What does this mean? It should be obvious to all that PGS and FET are very powerful technologies. They allow us to target and select the normal embryo(s) for embryo transfer to optimize the implantation and pregnancy rates. By using PGS and FET, the two above patients were able to select out the normal embryo that provided them with success and avoid multiple failed embryo transfer procedures. Also, by transferring a genetically normal embryo, the risk for a spontaneous abortion (miscarriage) tremendously decreases as PGS offers a 99% probability that the embryo is chromosomally normal (i.e. no Down’s syndrome). It is kind of like having an amniocenteses performed before pregnancy occurs.
At Dominion Fertility, most of our patients prefer NCFET rather than a medicated FET, as it is so simple and patient friendly and there are fewer medications. For patients who have irregular menstrual cycles, we perform medicated frozen embryo transfer. Both types of transfer, however, have the same chances for a successful pregnancy but many clinics only offer medicated embryo transfer. We believe that both types of FET should be available.
Another advantage performing PGS is the low multiple pregnancy rates. By transferring only one genetically normal embryo the twin rate is one percent. There is simply no need to transfer more than one PGS normal embryo in the vast majority of our patients.
You may wonder, why not simply transfer a PGS normal embryo during the fresh stimulated IVF cycle? There are 2 strong reasons why many premier infertility centers do not perform a fresh embryo transfer in the stimulated IVF treatment cycle. First, most centers now “trigger” ovulation using Lupron and not hCG to avoid the serious risks of ovarian hyperstimulation syndrome. Unfortunately, by triggering with Lupron, the endometrium often suffers making it unreceptive to the embryo for implantation. It is now well understood and medically documented that ovarian stimulation drugs (gonadotropins) commonly make the endometrium unreceptive to the embryo. Simply freezing the embryos and performing the embryo transfer outside of the stimulated IVF cycle easily circumvents this endometrial problem.
All of the above is ultra cutting edge technology. A new article titled, “Comprehensive chromosome screening improves embryo selection: a meta-analysis”, by Dahdouh et al, Fertility Sterility, Sept, 2015, concluded, PGS increases clinical and sustained implantation rates, thus improving embryo implantation rates and embryo selection. Other medical literature and our experience agree that PGS together with later frozen embryo transfer may benefit many patients undergoing stimulated IVF. Congratulations to my patients who have benefitted from these medical procedures. I am sure there will be many more successful patients!