What is Preimplantation Genetic Screening (PGS)?
PGS(Preimplantation Genetic Screening) testing is a genetic study of the embryos produced during your IVF cycle which has the goal of helping you have a successful pregnancy and a healthy baby.
PGS testing screens your embryos for any chromosomal abnormalities such as Down Syndrome, Patau Syndrome, Edward Syndrome, XY Chromosome Analysis, and Di-George Syndrome before transferring the embryo into your uterus. If you and your doctor feel you could benefit from this test, it fits easily into your routine IVF treatment.
The cycle would start as usual, with ovarian stimulation and monitoring. Your eggs would be retrieved and fertilized in the IVF lab. Then, after fertilization, an embryo biopsy is taken at typically day five or six of the embryo’s development, meaning that a few cells from the embryo are extracted and analyzed. Each cell should contain 23 pairs of chromosomes, or 46 chromosomes total. PGS testing assesses all 23 pairs of chromosomes, including the two sex chromosomes (X and Y) that determine the embryo’s sex. PGS testing can test to see if there are any extra or missing copies of chromosomes in each embryo.
A small sample of each embryo is sent to a genetic testing lab, but your embryos will safely be stored at your IVF clinic. Once the PGS testing is complete, results are sent back to your doctor, which can help identify which embryos should be transferred back to the uterus.
Overall, PGS helps to determine whether or not embryos appear to have the correct number of chromosomes. This is something many patients could benefit from, as it can increase pregnancy rates per transfer and reduce the risk of miscarriage, but it’s particularly recommended for the following:
If you’re over the age of 35 years old. In addition, as women age, the chance for chromosomal abnormalities in embryos increases. PGS testing can be incredibly helpful for these patients by testing for chromosomal abnormalities in embryos prior to transfer.
If you’ve experienced more than two miscarriages: PGS testing is known to reduce miscarriage rates by testing for chromosomal abnormalities in embryos prior to transfer. This is because around half of all miscarriages are due to chromosomal abnormalities.
If you’ve had multiple rounds of IVF that were not successful: PGS testing is known to increase the likelihood of a successful embryo transfer by identifying which embryos appear chromosomally normal. In turn, this may help eliminate the need for as many cycles of IVF.