|Thanks to the advances of science, those undertaking IVF treatment are able to check whether or not an embryo is chromosomally normal before being placed in the uterus. This technique is called Preimplantation Genetic Screening (PGS) – let's take a look at just what this method involves.
What exactly is Preimplantation Genetic Screening?
In simple terms, PGS is all about examining chromosomal copy number of all 24 chromosomes before they are transferred to the uterus by checking defects such as missing or extra chromosomes. For example, an extra copy of chromosome 21 can result in pregnancy affected with Downs Syndrome. Even embryos that appear flawless aren't necessarily so, making PGS an important tool in taking a more informed choice as to which one to use. The technique involves removing a small group of cells from the embryo and the cells are sent for genetic testing. The embryos are frozen and once the results are reported back, a chromosomally normal embryo can be thawed then placed back in the uterus.
PGS is used to screen chromosomal imbalance in the embryo. This test does not screen or give information to relating to genetically inherited conditions. This can, however, be carried out by a similar procedure called Preimplantation Genetic Diagnosis (PGD).
Although IVF treatment in itself can help a couple to conceive, when it is partnered with the PGS technique, the chances of falling pregnant significantly improve. This is because we estimate that up to 40 per cent of even high-quality embryos transferred in standard IVF, will have chromosome abnormalities that result in a failed treatment cycle. So, while PGS can be a valuable addition for all IVF cycles, it is particularly useful for women older 38 years where egg chromosome abnormalities are increased, and for women who have had several miscarriages.