PGS overview

THE IMPACT OF PREIMPLANTATION GENETIC SCREENING (PGS)

Human reproduction is a very inefficient process. It is estimated that of the couples who conceive naturally, more than 85% of them suffer early pregnancy losses and only about 10% end up delivering a baby nine months later. The main reason for early pregnancy losses in women are chromosomal abnormalities. So most if not, all pregnancies are at risk of developing chromosomal abnormalities. The risk increases as females age and nearly the majority of pregnancies are affected in women older than 40 years of age.

In cases of unexplained infertility, frequent pregnancy losses or miscarriages this problem can be prevented or diminished. The embryos are produced via In Vitro Fertilization (IVF) and then biopsied 5 to 6 days later. The biopsy is conducted to identify the embryos with a normal number of chromosomes. The technique used to examine the chromosome material of an embryo is known as Preimplantation Genetic Screening (PGS). It identifies the embryos with an abnormal number of chromosomes (clinically known as aneuploidy) so only those with a normal number of chromosomes (46) are selected for transfer to the uterus of the patient. This technique assesses the chromosomal health of embryos with the goal of improving the chance of pregnancy using IFV.

PGS is available for all patient and some providers perform it routinely alongside IVF for all patients. PGS can be particularly helpful for couples who had recurrent miscarriages, several failed IVF cycles or those with unknown causes of infertility.

The PGS process:

1. IVF: After ultrasound guided aspiration of the eggs from the ovaries, embryos are produced In vitro and incubated in the laboratory for a period ranging from five to seven days
2. EMBRYO BIOPSY AND PGS ANALYSIS: Once the embryos reach the blastocyst stage (after five or more days in culture) the embryologist carefully removes a small number of cells from the trophectoderm, the tissue that will give rise to the placenta. This step requires the use of micropipettes, a sophisticated inverted microscope with Hoffman modulation contrast and a computerized laser system to remove the cells without damaging the rest of the embryo. Depending on the embryo transfer plans they can be transferred immediately or saved for a later transfer.
3. VITRIFICATION OF BIOPSIED EMBRYOS. Non-transferred or excess embryos are stored at low temperatures using the VITRIFICATION technique. This is a quick procedure resulting in very high survival rates.
4. EMBRYO TRANSFER: One or two chromosomally healthy embryo are selected for transfer either fresh or after vitrification. Remaining embryos can be frozen for future use.

Chromosome makeup is a major contributing factor to having a successful pregnancy, but there are also a number of other factors involved. You can think of chromosome material as being one piece of the puzzle, but there are other pieces to consider. Other things that can contribute to a successful pregnancy include hormonal imbalances, inherited disorders, maternal anatomy and blood conditions. Be sure to consult with your doctor regarding all other risk factors.