Preimplantation Genetic Testing (PGT) - PGT-A & PGT-SR
What Is PGT
Preimplantation Genetic Testing (PGT) is a laboratory procedure performed during an IVF cycle. It involves analyzing embryos for genetic abnormalities before they are transferred into the uterus. This allows your fertility team to select embryos that are chromosomally normal or balanced, increasing the chances of a healthy pregnancy.
There are different types of PGT, depending on what is being tested:
1. PGT-A (Preimplantation Genetic Testing for Aneuploidy)
What It Is
PGT-A screens embryos for chromosomal aneuploidy, which refers to the presence of too many or too few chromosomes. A normal embryo has 46 chromosomes (23 pairs); an abnormal number can result in:
- Failed implantation
- Miscarriage
- Genetic conditions such as Down syndrome
Who Might Benefit
- Women over 35 years old
- Couples with repeated IVF failure
- Individuals with recurrent miscarriage
- Those seeking single embryo transfer (SET) with the best possible chance of success
Benefits
- Improves implantation rates
- Reduces risk of miscarriage
- Increases chance of a healthy baby
- Helps avoid transferring embryos with chromosomal abnormalities
2. PGT-SR (Preimplantation Genetic Testing for Structural Rearrangements)
What It Is
PGT-SR is used when one or both partners carry a chromosomal structural rearrangement, such as:
- Translocations (reciprocal or Robertsonian)
- Inversions
These rearrangements may not cause health problems for the carrier, but they can result in embryos with unbalanced chromosomes, leading to:
- Failed implantation
- Miscarriage
- Genetic disorders in offspring
Who Might Benefit
- Couples with a known chromosomal rearrangement
- Individuals with a history of miscarriage or infertility
- Those with a family history of genetic abnormalities
Benefits
- Helps identify balanced embryos suitable for transfer
- Reduces chance of passing on genetic issues
- Increases chance of a viable pregnancy
How the Testing Works
- Embryo Biopsy
- Performed at the blastocyst stage (Day 5 or 6)
- A few cells are removed from the embryo’s outer layer (trophectoderm)
- Genetic Analysis
- DNA is analyzed using advanced technology to check chromosome number and structure
- Embryo Freezing
- Embryos are frozen while results are processed
- Embryo Transfer
- A chromosomally normal or balanced embryo is selected for transfer in a future cycle
