Preimplantation Genetic Test (PGT)
Hope Healing Happiness
in Fertility Care
Intrauterine Insemination (IUI) is a type of fertility treatment where specially prepared sperm is placed directly into a woman’s uterus using a thin catheter.
Preimplantation Genetic Test (PGT)
What is Preimplantation Genetic Test ?
Preimplantation Genetic Diagnosis—now often referred to within the broader category of Preimplantation Genetic Testing (PGT)—involves the genetic screening of embryos created via IVF (In Vitro Fertilization) before implantation. It helps identify genetic disorders early, reducing the chance of miscarriage or a child born with a serious condition, and avoids the need for selective abortion later in pregnancy.
Because the procedure samples just a small group of cells (from the embryo’s trophectoderm—the part that becomes the placenta), the process requires extreme precision to avoid affecting the embryo, plus confirmatory tests like CVS or amniocentesis later.
When is PGT Considered ?
Embryo genetic testing may be recommended in the following situations:
- If a parent or the couple carries a known monogenic disorder (e.g., Huntington’s disease, cystic fibrosis, BRCA mutations).
- When structural chromosomal abnormalities (e.g., inversions, translocations) are present in a parent.
- After repeated IVF failures, recurrent pregnancy loss, advanced maternal age, or unexplained infertility.
- Many embryos naturally have chromosomal abnormalities—PGT helps identify the healthiest ones for transfer.
In short: IVF is considered when natural conception isn’t possible or other fertility treatments fail.
Types of PGT
PGT has three main categories, each tailored to specific genetic conditions:
- PGT-A (Aneuploidy screening) — formerly PGS — screens for missing or extra chromosomes. It helps reduce miscarriage and implantation failure.
- PGT-M (Monogenic disorders diagnosis) — formerly PGD — checks for specific inherited single-gene mutations like cystic fibrosis, muscular dystrophy, BRCA1/2.
- PGT-SR (Structural rearrangements) — screens for chromosomal translocations, inversions, or other abnormalities that increase miscarriage risk.
These modern terms (PGT-A, -M, -SR) have replaced older nomenclature (PGS and PGD) but retain similar functions.
Process of PGT
Results, Benefits and Limitations
Benefits
- Higher chance of successful pregnancy and live birth by selecting genetically healthy embryos.
- Reduces miscarriage risk, particularly in older women or those with recurrent reproductive losses.
- Avoids selective termination by ensuring embryos implanted are disease-free.
Limitations
- False positives/negatives: Some embryos may be misclassified due to mosaicism or testing limits. Confirmatory testing (like CVS or amniocentesis) is still recommended during pregnancy.
- Mosaicism: Genetic differences between biopsied cells and the embryo’s inner cell mass can lead to uncertain results.
- Ethical and emotional considerations: Includes concerns about embryo selection and what screenings should be offered.
- Cost and accessibility: PGT can be expensive and may not be covered by insurance.
- Controversies over utility: Some studies suggest that PGT-A may not significantly improve live birth rates in all groups.