Preimplantation Genetic Screening

Preimplantation genetic screening is a technology that is used to identify abnormalities in oocytes (eggs) or embryos when using IVF techniques. Prior to implanting an embryo into a woman’s uterus diagnostic screening is useful when one or both parents have a known genetic abnormality so only unaffected embryos can be evaluated and transferred to the uterus.

The detection of abnormal oocytes (eggs) in IVF treatments, prior to implantation, is also important as studies show that 90% of embryos are aneuploid (chromosomally abnormal) as a result of defective oocyte mechanisms that cause abnormal cell division in the embryos of parents that are otherwise thought to be chromosomally normal. The risk of some chromosomal abnormalities, such as Downs Syndrome, can also increase with the mother’s age.

Preimplantation genetic testing provides an alternative to current post-conception diagnostic procedures, such as amniocentesis, which tests the amniotic fluid surrounding the foetus during the 15th to 20th week of pregnancy or chorionic villus sampling (the testing of placental tissue) at 10 to 12 weeks of pregnancy, and therefore avoids the difficult decision of pregnancy termination if the results are unfavourable.