Pons Medical Research

What Is PGS?

Preimplantation genetic screening (PGS) is a reproductive technology used with an IVF cycle to increase the potential for a successful pregnancy and delivery. It is a genetic test on cells removed from embryos, allowing to select the healthy euploid  embryo(s).

What Are The PGS Steps During The IVF Cycle?

After embryos are created in the laboratory, they are grown for five to six days. On day five and again on day six, the biopsy for PGS is done on all blastocysts. Biopsy involves removing a few cells from the trophectoderm, or the layer of cells that is  “hatching out” of the embryo at this stage of development. The embryos are stored while the genetic material from the removed cells is tested for abnormalities in a genetic lab.

Are Biopsy And PGS (Preimplantation Genetic Diagnosis) Safe?

Yes. Data from from thousands of live births in humans indicate that PGS does not lead to an increase in birth defects over that of the general population. In embryos where chromosomal microarray testing is performed, one can expect fewer pregnancies with chromosomal disorders since most chromosomal disorders are identified prior to transfer of the embryos to the uterus. Removal of a few of the cells of the early embryo does not alter the ability of that embryo to develop into a complete, normal pregnancy.

How Are Embryos Chosen For Transfer?

Embryos that have both a normal test result and appearance (morphology) can be transferred in a cryoembryo transfer (CET) cycle. While embryo morphology is helpful in selecting the best embryos for transfer, it is known that many embryos with significant chromosome abnormalities may have normal morphology. Therefore, PGS results help to better identify those embryos that can be safely transferred to the uterus. The combination of normal genetic testing with normal physical appearance indicates the highest chance of achieving a healthy pregnancy. All decisions regarding which embryo(s) to transfer to the uterus and how to use the remaining embryos are made together between the couple and our medical team.

Which Tests Are Available In Our Clinic?

In our Clinic we perform the PGS (Preimplantation Genetic Screening) of 24 chromosomes, testing for aneuploidies. We also perform PGD for monogenic diseases. 

Which Genetic Disorders Can Be Prevented By Means Of PGS?

Here we have listed a few examples of aneuploidies (and the corresponding genetic disorder) of certain chromosomes that can be prevented by using PGS:

  • Chromosome 13: Breast And Ovarian Cancers, Deafness, Wilson Disease
  • Chromosome 15: Marfan Syndrome, Tay-Sachs Disease
  • Chromosome 16: Polycystic Kidney Disease, Alpha Thalassemia
  • Chromosome 17: Charcot-Marie Tooth Disease
  • Chromosome 18: Niemann-Pick Disease, Pancreatic Cancer
  • Chromosome 21: Down Syndrome
  • Chromosome X: Duchenne Muscular Dystrophy (DMD), Turner’s Syndrome, And Fragile X Syndrome
  • Chromosome Y: Acute myeloid leukemia

Can The Sex Of The Baby Be Selected With The Help Of PGS?

Yes. Even if the PGS test was not designed to perform the selection of the sex of the future baby, it will give us useful information including the sex of every single embryo created during the IVF cycle. It is therefore possible to determine beforehand which embryos will be implanted. The selection can be done together with the Intended Parents.

Read more about Pros and Cons of PGD and How to reduce the risk of miscarriage with the help of PGS in our Blog!


Didn’t you perform PGS before the pregnancy?

Read more about the Harmony test and its necessity during the pregnancy in our blog!

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