PGT - A
Preimplantation Genetic Testing for Aneuploidies, PGT-A (formerly PGS) is a genetic test performed on embryos to identify numerical chromosomal abnormalities (aneuploidy).
Preimplantation Genetic Testing for Aneuploidies, (PGT-A) involves the biopsy of embryos to help embryo selection based on information obtained following genetic testing. One would need to undergo ovarian stimulation to retrieve eggs from the ovaries. These are then used to create embryos with the help of sperm. Five days later, embryos that reach the blastocyst stage are biopsied and cryopreserved. The genetic material is then sent for testing to a specialised laboratory. It can take 3-4 weeks to get the results. A chromosomally normal embryo is then transferred into the womb in a subsequent cycle.
Why use PGT-A?
- Increases pregnancy rates per transfer due to the selection of a normal embryo.
- Reduction in miscarriage rate as the vast majority are due to aneuploidy.
- Increase in the likelihood of having a healthy baby as some pregnancies with chromosomal anomalies can give rise to the birth of baby with a serious illness.
- Reduction in time and cost to achieve a pregnancy.
- Reduces risk of multiple pregnancy by a encouraging the transfer of a single embryo.
Who should use PGT-A?
- PGT-A is particularly important for patients over 35, as aneuploidy rate increases with maternal age from approximately 50% at maternal age under 35, to approximately 80%, at age 42.
- Those with a history of recurrent miscarriages and implantation failures.
What are the limitations of PGT - A?
- Accuracy is ~98%, hence prenatal testing is recommended.
- PGT-A tests only the samples produced by embryo biopsy, not whole embryos.
- PGT-A does not detect structural abnormalities that do not involve gains or losses of genetic material.
PGT-A | Preimplantation Genetic Testing - Aneuploidy | Embryo Biopsy (3:09)