What is PGD/PGS – Aneuploidy Screening?
PGD/PGS is the screening of embryos for chromosomal abnormalities which aims to improve the chances of pregnancy and having a healthy baby.
In situations where one of the parents is a carrier of a specific chromosomal or gene defect, PGD/PGS can be performed. Embryos are tested for these specific defects and only normal embryos are used.
Research has shown that chromosomal abnormal (aneuploidy) embryos contribute to poor IVF outcomes. Aneuploidy screening allows the analysis of specific chromosomes to be performed on a single cell removed from an embryo or egg. Following chromosomal analysis, only the embryos that test normal for the chromosomes analysed are selected for transfer to the uterus. The number of chromosomes analysed is limited and depends on the technique used. A new technique developed (CGH) will allow the analysis of more chromosomes with a better outcome.
PGD/PGS is performed on embryos created through IVF, prior to their implantation in the uterus. There are hundreds of conditions that the embryos can be tested for including Cystic Fibrosis, Thalassemia and Tay-Sachs amongst others.
Embryos selected for PGD/PGS for must undergo an embryo biopsy, which is equivalent to surgery on the embryo at a microscopic level. Approximately 2-5 cells are removed from the outer layer of the embryo. These cells contain the same genetic information as the inner cells of the embryo. This embryo is then safely kept in its incubator until the PGD/PGS results are ready. If the results are clear, the embryo is then placed in the uterus, with the hope that it will implant.
Who can benefit from PGD/PGS?
The following patient groups can benefit from PGD/PGS:
- Women aged 40 and above
- Couples who have repeated IVF failures
- Women who suffer from recurrent miscarriages
- Known specific chromosomal or gene defect with either partner
If there are further embryos that have been screened and are normal, the couple will have the option to freeze these for later use.