What is PGS testing?
Preimplantation genetic screening, or PGS for short, involves screening embryos during the in vitro fertilization (IVF) process. The test looks for abnormalities in the number of chromosomes in the embryo. Genetically normal embryos—those with the right number of chromosomes—increase success rates of implantation and decrease chances of having a miscarriage with IVF. Because of this, PCS testing can increase your IVF success rate.
What happens during PGS testing?
PGS testing is done on embryos that are five days old. By this time, the embryo has divided into multiple cells. At this point, one or multiple cells will be taken from the embryo for testing. Once this happens the embryos will be frozen until they are ready to be implanted.
The harvested cells are then examined to figure out how many chromosomes are present. Once fertility doctors have this information, they use it to choose the most viable embryos for implantation during IVF. Additional good embryos may be frozen and stored for future IVF cycles, if desired.
Results will be available roughly 7–10 days following the cell extraction.
Who should get PGS testing?
PGS testing is recommended for individuals or couples who are determined to be at risk of creating abnormal embryos. You may be at risk if:
- There is a history of genetic issues that can potentially be passed on to your embryos
- You are a woman over 35
- Several other fertility treatments have failed
- You have experienced recurring miscarriages and/or “chemical” pregnancies
How does PGS testing improve the IVF process?
Numerous studies of fertility clinic data have shown PGS testing to increase your success rate when using IVF. There are a variety of areas in the IVF process where PGS can help.
Increase chance of successful implantation
Healthy embryos are more likely to be carried to term. By implanting the most viable embryos, you increase your chance of IVF working to get you pregnant and deliver.
Reduce your risk of miscarriage
Chromosomal abnormalities may be the cause of recurring miscarriages. Because of this, implanting a healthier embryo can reduce this risk.
Reach success in less cycles
Many couples need more than one cycle of IVF to find success. The process is expensive and invasive, costing time, money and emotional investment each go around. By pre-screening embryos you increase your chances of having a successful cycle in less time.
Minimize risk of multiple pregnancies
It is quite common for IVF to lead to multiple births (twins, triplets, and so on). This is because couples often choose to implant multiple embryos as the risk of losing an embryo during IVF is very high. PGS testing allows you to be more confident in the viability of an embryo so that your fertility doctor can implant one embryo instead of multiple and still be confident about your chances of carrying a baby to term.
Increase our chances of delivering a healthy baby
Chromosomal abnormalities can lead to babies who are born with serious illnesses and other issues. Implanting embryos without these abnormalities increases our chances of having a healthy baby.
How safe is PGS testing?
PGS testing is a delicate and complicated test that happens at a pivotal moment during embryo growth. This may have you wondering just how safe PGS testing is. PGS testing completed by an experienced doctor and lab carries little risk to the embryo. A 2010 study showed that PGS testing does not lead to birth defects at all.
Though rare, it’s important to know that there are some risks associated with the PGS test. First, there is a small risk of damaging the embryo during the cell biopsy (extraction). Choose a skilled doctor to mitigate this risk. Second, you may find that no embryos are free of chromosomal abnormalities. This happens most often due to maternal age. While this can be discouraging, it is also important information to have as you decide the next step in your journey. Finally, there is a chance that the PGS test results will be inconclusive. In some cases, both normal and abnormal cells are found in the sample. This is called mosaicism.
PGS vs PGD
You may also have heard of preimplantation genetic diagnosis (PGD). While they are similar, there are very specific distinctions between PGS and PGD and they do not accomplish the same thing. PGD is another type of screening that is performed during the IVF process prior to embryo transfer. PGD is used to detect traits such as:
- Sex of the embryo
- Presence of single-gene disorders
- Chromosomal translocations
PGS detects abnormalities in the number of chromosomes in a cell and is good for identifying diseases such as Down syndrome. PGD detects certain gene mutations or DNA changes and is good for identifying diseases such as Cystic fibrosis and sickle cell anemia.