Limitations in Preimplantation Genetic Screening (PGS) Result in Normal Embryos being Discarded after IVF, According to a New Paper

Due to mosaicism in embryos, preimplantation genetic screening (PGS), a popular add-on procedure in IVF cycles, produces many false-positive results, and perfectly healthy embryos end up being unnecessarily discarded, according to a new paper.

NEW YORK, NY, September 07, 2016 /24-7PressRelease/ -- A consortium of infertility centers just published a paper in the medical journal Reproductive Biology and Endocrinology, questioning the utility of an increasingly popular procedure utilized with in vitro fertilization (IVF). The procedure, called preimplantation genetic screening (PGS), tests embryos prior to embryo transfer for chromosomally abnormalities.

The hypothesis behind PGS is that exclusion of chromosomally abnormal embryos will increase pregnancy and live birth rates in IVF, and reduce miscarriage rates. The consortium attracted international attention for the first time at the October 2015 Annual Meeting of the American Society for Reproductive Medicine (ASRM), when it reported on three healthy live births after transfer of embryos, which, based on PGS, had been reported chromosomally abnormal (aneuploidy). The authors then argued that the establishment of pregnancies and healthy births from allegedly "aneuploidy" embryos suggested that PGS was not only an inaccurate diagnostic procedure but, likely, resulted in the mistaken discarding of great numbers of normal embryos. The consortium's position was further strengthened when Italian and Spanish investigators recently reported more normal births after transfer of allegedly "aneuploid'" embryos.

In the just published manuscript, the authors expanded the number of reported healthy live births after transfer of allegedly "aneuploid" embryo to five. In addition, reporting on a study where embryos declared aneuploid were re-biopsied and re-tested in multiple biopsies in a different PGS laboratory, they demonstrated a surprisingly high degree of divergence in results between biopsies. They concluded that the degree of mosaicism (presence of multiple cell lines carrying different chromosomal compositions) at early stages of embryo development makes accurate diagnosis of embryos by PGS impossible. PGS, the authors cautioned, produces a significant number of false-positive diagnoses, leading to the discarding of healthy embryos, and should be abandoned as a procedure to improve IVF outcomes.

The senior author of this manuscript, Norbert Gleicher, MD, is available for further comments. He is Medical Director and Chief Scientist of the Center for Human Reproduction in New York City, a leading clinical and research center in fertility disorders, and Adjunct Professor at Rockefeller University in New York City and at the Medical University Vienna, Vienna, Austria.

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