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PGS (PGT-A) – Preimplantation Genetic Testing for Aneuploidies
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What is PGS (PGT-A)?
PGS, also called Preimplantation Genetic Testing for Aneuploidies (PGT-A), is a procedure that examines embryos for abnormal chromosome numbers before IVF embryo transfer.
👉 This technique is commonly used as part of a complete IVF treatment plan.
Benefits of PGS (PGT-A):
- Select Healthy Embryos for Implantation – Avoid transferring embryos with chromosomal abnormalities, improving implantation rates.
- Increase Pregnancy Success and Shorten Treatment Time – Ideal for couples with previous IVF failures or advanced maternal age.
- Reduce Miscarriage and Birth Defects – Helps identify chromosomal issues and reduces the risk of miscarriage, especially for those with recurrent pregnancy loss or a family history of chromosomal disorders.
👉 Learn more about recurrent implantation failure and how embryo selection may help improve outcomes.
Who Should Consider PGS (PGT-A)?
- Women aged 35 or older
- Individuals with more than 2 previous miscarriages
- Couples with repeated IVF failures
- Couples with a family history of chromosomal abnormalities or translocations
- Male infertility syndromes
Conditions PGS Can Detect:
- Chromosomal aneuploidies such as Down Syndrome, Turner’s Disease, Edward’s Disease, Patau Disease
- Large chromosome deletion (>10Mb) such as Prader-Willi Syndrome, Cri Du Chat Syndrome, DiGeorge Syndrome, Angelman Syndrome
Limitations of PGS (PGT-A):
- The embryo could be mosaic, and depending on the severity of the case it may be unable to develop normally after transfer
- The sample size is small (<10Mb)
- Cannot distinguish balanced and structurally normal embryos from translocation carriers
*Please receive a Chorionic Villus Sampling (CVS) or Amniocentesis after a successful pregnancy through a PGT-A test.*
👉 For detecting specific inherited genetic diseases, PGD (PGT-M) may be recommended alongside PGT-A.
FAQ – Common Questions About PGS (PGT-A):
Q: Does PGS guarantee a healthy pregnancy and child?
A: While PGS improves the chances of a successful pregnancy, it cannot detect all chromosomal or genetic abnormalities. Regular prenatal checkups are essential to monitor pregnancy health.
Q: Can PGS improve IVF success rates?
A: Yes, PGS helps select healthy embryos, reduces miscarriage risk, and is especially beneficial for older women or couples with repeated IVF failures.
Q: How is PGS performed?
A: At the blastocyst stage, 5–8 cells are taken from the outer layer (trophectoderm) of the embryo for genetic testing. This process minimizes harm to the embryo while providing a reliable chromosomal assessment.
Case Example:
A 39-year-old patient with previous miscarriages underwent PGS (PGT-A) at NUWA Fertility Center. Out of 13 eggs retrieved, 7 blastocysts were tested, with only one mosaic embryo detected. Adjusting treatment strategies, 2 chromosomally normal embryos were eventually transferred, leading to a successful pregnancy.
👉 PGT-A is especially beneficial for patients with advanced maternal age or prior IVF challenges.