PGS vs. PGD Understanding the Differences
At Arizona Associates for Reproductive Health, many of our IVF patients are ideal candidates for genetic screening. Genetic screening allows us to analyze embryos prior to transfer, so that those with chromosomal or genetic abnormalities are not selected for implantation. The two types of tests offered are preimplantation genetic screening, or PGS, and preimplantation genetic diagnosis, or PGD.
Individuals from Scottsdale, and Gilbert, AZ, who are candidates for genetic testing are likely to have questions about which of these procedures is right for them. Our fertility specialists are happy to go over the differences between PGS vs. PGD testing, and explain which test is most appropriate for each of our patient’s unique needs.
What Is PGS?
PGS is a test that is available to all IVF patients. The test allows us to look at the chromosomes of each mature embryo. During a PGS procedure, a small set of cells is collected from the embryo. These cells are sent to our genetic lab for analysis. The test is not harmful to the embryo, nor does it put the intended mother at any risk, since the test is performed before the embryo has been transferred to the uterus.
A normal embryo has 46 chromosomes, or 23 from each parent. If an embryo is missing a chromosome or has an extra chromosome, it is considered abnormal. It is important to identify abnormal embryos prior to embryo transfer, because abnormal embryos are less likely to successfully transplant and result in pregnancy. When an abnormal embryo does transplant, there is a higher risk of miscarriage. PGS allows us to identify general abnormalities that can compromise the success of IVF treatment, as well as those that can lead to conditions such as Down syndrome, Turner syndrome, or Trisomy 13.
What Is PGD?
PGD is another type of test that may be offered to our Scottsdale IVF patients. PGD uses the same type of technology as PGS to pre-screen embryos before they are selected for transfer. However, the information that is analyzed by a PGD test is different than that which is collected by PGS.
PGD screens single cells from an embryo to look specifically for genetic diseases or chromosomal abnormalities that can be passed down from a parent to their child. For example if a person suffers from cystic fibrosis, or is a known carrier of cystic fibrosis, a PGD test can look at the genes of an embryo to determine if the same genetic mutation is present. This allows patients to select embryos that are free of the genetic condition for the transfer procedure.
PGD testing also allows us to determine the sex of an embryo prior to transfer. Sex selection may be offered to couples who are looking to balance out the dynamics of their family. But more importantly, sex selection lets patients avoid passing on a sex-related genetic condition to their child.
Which Test Is Right For Me?
Our fertility specialists are happy to advise patients as to which type of genetic screening is most appropriate for them. Generally, any IVF patient can be a suitable candidate for PGS testing, while the pool of PGD candidates is more select. PGD testing is offered when one or more parent has a known genetic disorder (or is the carrier for one) and is aware of the specific gene mutation that has caused it.
If you are preparing for IVF treatment and have questions about PGS vs. PGD testing, the fertility specialists at Arizona Associates for Reproductive Health would be happy to provide you with more information. To schedule a personal consultation, send us a message online, or call (623) 469-3992.