What Is Preimplantation Genetic Diagnosis (PGD)?
For many parents pursuing surrogacy and/or egg donation at our Boston, San Francisco, and New York offices, the term PGD may come up. This reproductive technology is used with an in vitro fertilization (IVF) cycle and can be used to diagnose genetic disease in early embryos prior to implantation in your surrogate mother. You may have also heard of the term preimplantation genetic screening (PGS), which doesn’t look for specific diseases but uses PGD techniques to identify at-risk embryos. Here we take a look at how the test works to help you determine if it’s right for you.
How is preimplantation genetic diagnosis performed?
PGD begins with IVF that includes egg retrieval and fertilization in a lab. Over the next 3 days, the embryo will divide into 8 cells. Then 1 or 2 cells are removed from the embryo. The cells are then evaluated to determine if the inheritance of a problematic gene is present in the embryo. Once the procedure has been performed and embryos free of genetic problems have been identified, the embryo is implanted in the surrogate’s uterus in hopes of a successful pregnancy.
According to the American Pregnancy Association, these are the specific steps of the PGD process:
First, a couple/few cells are microsurgically removed from the embryos, which are about 5 days developed. After this cell collection, the embryos are safely frozen.
The DNA of the cells is then evaluated to determine if the inheritance of a problematic gene is present in each embryo. This process takes at least one full week.
Once PGD has identified embryos free of genetic problems, the embryo(s) will be placed in the uterus (usually by an IVF procedure), and the wait for implantation and a positive pregnancy test begins.
Any additional embryos that are free of genetic problems are kept frozen for possible later use while embryos with the problematic gene(s) are destroyed. This testing process may take weeks. (You can learn more about the options for remaining embryos in this related blog post.)
What are the benefits of PGD?
The reason intended parents (IPs) opt for PGD is because it can test for more than 100 different genetic conditions. Since the procedure happens before implantation, it allows IPs to decide if they wish to continue with the surrogate’s pregnancy. It’s important to keep in mind, however, that it doesn’t completely eliminate the risk of conceiving a child with a genetic disorder. It is also important to note that preimplantation genetic diagnosis does not replace the recommendation for prenatal testing.
If you’re interested in learning more about PGD testing, talk to your IVF doctor. And if you’re part of the Circle program, your program coordination team can connect you to the right people.
Thinking about becoming a parent with the help of a surrogate or egg donor? Visit circlesurrogacy.com