Pre-implantation Genetic Screening (PGS)
Pre-implantation Genetic Screening (PGS) gives us the ability to test embryos for chromosomal abnormalities to identify the embryos with the best chance of developing into healthy babies.
This means that with PGS, we now have the potential to improve IVF success rates by identifying embryos which have the correct number of chromosomes.
Between 40% and 75% of human embryos may contain an abnormal number of chromosomes, depending on the woman’s age. Most chromosomally abnormal embryos will not implant and if they start to implant are most likely to miscarry.
PGS makes it possible to screen embryos to select only those chromosomally normal for embryo transfer resulting in a higher chance of successful implantation and a reduced risk of miscarriage. Using the very latest PGS techniques, we can now screen all 24 chromosomes in each embryo and this can significantly increase IVF success.
In order to perform PGS, a few cells are removed from each embryo and sent to a genetics laboratory for testing. The embryos are then frozen until the results are ready and those with the correct chromosome number considered for embryo transfer, usually one at a time.
PGS is helpful for:
The most common factor for unsuccessful IVF is female age. This is due to the increase in chromosomal abnormalities in eggs and subsequently embryos as women get older. Chromosomal abnormality is a major factor in failure of embryos to implant, so screening all 24 chromosomes and only transferring the embryos with the correct number of chromosomes can significantly improve the chance of a successful pregnancy.
Women with a medical history of repeated miscarriages or failed IVF treatments
One of the main reasons for miscarriage and IVF failure is chromosomal abnormality. PGS screens embryos to ensure they have a normal number of chromosomes to reduce the risk of miscarriage and increase IVF success.
Couples at risk of transmitting chromosomal alterations
When an embryo with the incorrect number of chromosomes does develop, there is a higher risk of the child having severe development or learning difficulties. For example, an extra copy of chromosome 21 results in a child being born with Downs Syndrome.
Pre-implantation genetic screening has the potential to:
1. Greatly improve IVF birth rate per embryo transferred
2. Minimize the incidence of miscarriages and birth defects caused by irregularity in the chromosome number of eggs
3. Reduce the incidence of multiple pregnancies whilst maintaining a high live birth rate