Pre-Implantation Genetic Screening (PGS), is an IVF procedure designed to examine your embryos for chromosomal abnormalities. It is an established treatment option to improve your chances of conceiving a healthy baby if you’ve experienced repeated IVF failure, recurrent miscarriage or have had a previous pregnancy with a chromosomal abnormality such as Down syndrome.
The initial part of the IVF cycle is carried out in the same way as for infertility and consists of five basic steps:
The most common PGS protocol used today is to biopsy the embryo on the fifth day after the egg has been fertilized. Embryologist removes a few cells from each multi-celled embryo (> 100 cells). The biopsied cells, containing the chromosomes representing that embryo, are specially prepared and couriered to the genetics laboratory.
The alternative to IVF-PGS is for a couple to achieve a pregnancy naturally, or through conventional fertility treatment, and to rely on prenatal diagnosis through chorionic villus sampling (CVS) or amniocentesis using similar molecular diagnostic techniques. With these techniques, more material can be sampled from a pregnancy and more time taken for interpretation. Misdiagnosis may also occur, but less frequently than with PGS. However, the only options for the couple at this time are either giving birth to a child with the defect, or termination of the pregnancy.