PGS | Preimplantation Genetic Screening Explained

The future of accurate and dependable genetic embryo screening has arrived: Preimplantation Genetic Screening (PGS) using Next Generation Sequencing (NGS).

Every decade or so a reproductive technology comes along that revolutionizes infertility treatment. Preimplantation Genetic Screening (PGS) by Next Generation Sequencing (NGS) is one such technology. PGS with NGS is a highly consistent platform and is the future of genetic and embryo screening.

The purpose of PGS is to analyze, select and transfer only embryos that have the appropriate number of chromosomes. Next Generation Sequencing (NGS) allows for high resolution screening which includes more in-depth analysis than simply counting the chromosomes. Preimplantation Genetic Screening with NGS offers patients extremely reliable results with an easy to understand fee structure.  

Why Use Preimplantation Genetic Screening (PGS)?

Aneuploidy is the term used to describe any embryo with either too many or too few chromosomes. The normal amount for humans is 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, decides female and male. Most people are not aware that aneuploidy is the cause of greater than 60% of miscarriages, as well as the most likely reason that patients do not get pregnant from an in-vitro fertilization (IVF) cycle with unscreened embryos.

Screening embryos in advance can help achieve higher implantation rates and fewer pregnancy losses. The utilization of PGS is particularly important for patients over 35 as they are more prone to chromosomal errors in their eggs due to the “biological clock”, patients with multiple-failed IVF cycles or implantation failure, and patients with a history of many miscarriages or clinical Recurrent Pregnancy Loss (RPL). This technology also provides the ability to prescreen for aneuploidy conditions and chromosomal abnormalities. 

How PGS with NGS is Utilized

Using PGS, we obtain 5-10 cells, from several hundred cells, of a day 5 or 6 embryo called a blastocyst. The ability to determine this chromosomal information is extremely important in choosing the right embryo for transfer. Many embryos that are graded based solely on how they appear do not prove to be chromosomally normal. Conversely, embryos that do not appear as healthy can be completely normal chromosomally. Biopsying the embryo at a more advanced cell stage dramatically increases the accuracy of this testing and minimizes any potential damage that the biopsy can cause to the embryo.

PGS with NGS and Elective Single Embryo Transfer (eSET)

Another advantage to utilizing PGS with NGS is that this technology can greatly reduce the odds of a patient having multiple pregnancies (twins or triplets) by choosing to have an Elective Single Embryo Transfer or eSET. Physicians can suggest eSET, with the knowledge that they are transferring the most chromosomally fit embryo, therefore precluding the need to transfer multiple, unscreened embryos in the hope that one will be healthy enough to create an ongoing pregnancy and a healthy baby.

Additional Facts about PGS with NGS

PGS is not a perfect science and does have inherent false positive and negative results due to the limited number of cells available for testing and embryo mosaicism. Based on current data the error rate is less than 1%. As with any technology, we recommend that patients err on the side of caution and when a pregnancy is established, traditional prenatal diagnosis like chorionic villus sampling or amniocentesis should be dependent of their obstetrician’s recommendation.

RMACT believes Preimplantation Genetic Screening (PGS) with Next Generation Sequencing (NGS) can be a benefit to any patient seeking to increase their chances of achieving a healthy pregnancy. For more information about PGS, or to speak with one of our board certified Reproductive Endocrinologists and infertility specialists, please contact us. We’re here to help.