Pre-Implantation Genetic Diagnosis (PGD) & Screening
Preimplantation genetic diagnosis, or PGD, is a micromanipulation technique that allows us to test embryos created with IVF for certain types of genetic conditions. Diseases such as Tay-Sach's, sickle cell anemia, or cystic fibrosis can cause severe pain, lifetime disability, and even death. For couples who know that they carry the genetic predisposition for such diseases, the chance to ensure that it will not be passed on to their children can be the difference between happiness and immeasurable suffering.
A PGD biopsy is performed once the embryos have reached the three-day stage, when there are at least six to eight cells. At this stage, there is no specialization of cells, so the removal of one or two will not harm the embryo or result in developmental damage. The testing phase of preimplantation genetic diagnosis will take place next, at which time the extracted cells will be examined for indications of the genetic disease. The type of test performed depends on what the embryo is being screened for. Once it has been determined which embryos carry the condition and which do not, the embryo transfer procedure can be performed with the healthy embryos.
It is important to recognize that PGD is not a general screening method. It allows us to check for specific conditions and is offered to couples who know that they carry a genetic disease and have a high risk of passing that condition on to their children.
Women who undergo preimplantation genetic diagnosis significantly reduce their chances of having a baby with a genetic disease. However, it is recommended that additional testing be conducted once the pregnancy is established, just to be sure. A chorionic villus sampling can be performed at 10 to 12 weeks, or an amniocentesis can be performed after 15 weeks. Each of these tests is highly effective for ensuring that the developing fetus is healthy and normal.