Preimplantation Genetic Testing (PGT)
What is PGT?
Preimplantation genetic diagnosis (PGT) is an advanced genetic test performed before pregnancy. Embryos obtained by IVF are tested for chromosomal abnormalities or a known genetic mutation. Only the unaffected ones are transferred into the uterus for the woman to conceive with a healthy baby. We can look for things like cystic fibrosis, thalassemia, Tay-Sachs disease, sickle cell disease, and over two hundred other genetic diseases.
When is PGT used?
PGT is used when chromosome abnormalities (aneuploidies) are associated with failed implantation, pregnancy loss, and the birth of children with multiple congenital anomalies. PGT provides a means of testing for these chromosome abnormalities and selecting the best embryos for transfer. Embryos with chromosome abnormalities are physically indistinguishable from healthy embryos; therefore, without PGT, abnormal embryos are equally likely to be transferred, reducing the chances of achieving a viable and healthy pregnancy.
There are four different kinds of PGT procedures:
PGT-A: Aneuploidy, formerly called PGS. ( This is a general screen)
PGT-M for Monogenic disorders. (This looks for specific disorders that you and your partner are carriers of)
PGT-HLA for matching. (This looks for an HLA match for an affected child you already have)
PGT-SR, structural, formerly translocations. (If you or your partner have chromosomes that are translocated, this test will look for embryos whose chromosomes balanced translocations, meaning they are compatible with life)
how is pgt different from ivf?
In this type of a cycle, the monitoring and retrieval are the same for you as in a regular IVF cycle as well as fertilization. However, after the retrieval, besides beginning the antibiotics, your cycle is complete. In the IVF lab, the embryologist will culture the embryos for 5-7 days and keep you updated to their progress. If you choose, all embryos that make it to the blastocyst stage are biopsied for testing and the embryos are then frozen. All biopsies will be sent to RGI for the genetic testing. Therefore, there is no transfer at this time.
You should expect your period to begin 5—14 days after the retrieval. With this period, you are encouraged to come in for morning monitoring for a new baseline ultrasound and blood tests to either begin a Frozen Embryo Transfer (FET) cycle or to begin another fresh IVF cycle if you are trying to generate more embryos.
how can i prepare for pgt?
Unless otherwise directed by your insurance, at IHR, we use RGI (Reproductive Genetic Innovations) for all our embryo testing. A consult with a genetic counselor at RGI is required if you are considering or need the embryos to be tested. They will consult with you regarding PGT expectations and will also have their own consent for you to sign. The consult may take place either in person in their office in Northbrook, or via the phone.
If you are doing PGT-M for a specific disorder, you must reach out to them as soon as you can as they will need time to prepare their probes to specifically tailor to your needs. Depending on the disease, the setup of these probes can take up to 6 weeks to complete. The IVF cycle cannot begin until the setup is complete. If you are planning on doing PGT-A only, then there is no setup required and no delay in getting started with your IVF cycle.