Understanding PGS/PGD Testing

PGS/PGD are techniques that test a patient's embryos for possible genetic abnormalities. They are only done during an in vitro fertilization procedure (IVF), at the point in which the eggs have been retrieved and fertilized and developed into embryos in the lab. Technicians will extract cells from the embryos and analyze them for chromosomal defects. Embryos that show no signs of defects and that continue to be viable can then be implanted, providing a higher chance of a healthy baby.

Preimplantation genetic screening checks embryos for abnormal chromosomes, making sure the embryos have the right ones and the right number. Down syndrome, for example, is a genetic abnormality caused when a person has three copies of chromosome# 21 instead of two. For women who are older than 35 or who have repeated unexplained pregnancy loss or IVF failure, PGS is a way to screen to find the healthiest, hardiest embryos for implantation. PGS is an effective way to maximize the chance of a healthy pregnancy through IVF, enabling one embryo to be transferred at a time while achieving high pregnancy rates that have only been seen in the past by transferring multiple embryos into the uterus. Using PGS with transfer of a single embryo will minimize the chances of twin pregnancies.

Preimplantation genetic diagnosis is used to screen for a specific genetic mutation or abnormality. Parents who have or carry the sickle cell trait, for example, may screen to make sure they are not passing this disease or trait down to future generations. In addition to sickle cell, PGD screens for Tay Sachs, Cystic Fibrosis, Muscular Dystrophy or Hemophilia and any other diseases caused by genetic mutations. Parents who have gotten pregnant in the past and discovered their child had a life-threatening or fatal genetic disease often want to use PGD in order to ensure that implanted embryos that do not have that disease.

Several recent studies put the accuracy of the screening process over 99%. Because the screening is done during the IVF process, it is only one extra step in the procedure. The latest technique for PGD/PGS, called blastocyst biopsy or trophectoderm biopsy, is being done at Carolina Conceptions. It is more accurate than previous methods and does not harm developing embryos. Embryos are tested after 5 days of development, after they have proven to be viable in the lab. The combination of PGS with IVF is so successful that Carolina Conceptions offers the ONE program, where a single normal embryo is used to attempt pregnancy. If a pregnancy does not result, Carolina Conceptions will perform treatment with frozen embryos for free.