Preimplantation Genetic Testing: How It Helps in Choosing a Healthy Embryo

Understanding Preimplantation Genetic Testing

Preimplantation genetic testing is a revolutionary advancement in IVF treatment that helps select healthy embryos, reducing the risk of genetic disorders. This specialised screening process enables fertility specialists to examine embryos for potential genetic abnormalities before implantation, improving the chances of a successful pregnancy and a healthy baby.

How Preimplantation Genetic Testing Works

During in vitro fertilisation (IVF), embryos are created in a controlled laboratory environment. Before implantation, preimplantation genetic testing (PGT) is performed on the embryos to identify chromosomal abnormalities or inherited genetic conditions. The testing process involves:

1. Embryo Development – After egg fertilisation, embryos are cultured in the lab for 5-6 days to the blastocyst stage.
2. Biopsy Procedure – Around 5-6 cells are carefully extracted from the outer layer(trophectoderm) of each embryo.
3. Genetic Analysis – These cells undergo detailed genetic screening to identify any abnormalities.
4. Selection of Healthy Embryos – Only embryos free from specific genetic issues are chosen for transfer.

By selecting embryos with normal genetic makeup, preimplantation genetic screening enhances the likelihood of a successful pregnancy while reducing the risk of miscarriage or inherited diseases.

Types of Preimplantation Genetic Testing

1. Preimplantation Genetic Testing for Aneuploidy (PGT-A)

PGT-A screens embryos for the number of chromosomes (aneuploidy). Chromosomal abnormalities can lead to conditions such as Down syndrome, Edwards syndrome, or Turner syndrome. By ensuring embryos have the correct number of chromosomes, PGT-A increases the success rates of IVF cycles and decreases the likelihood of failed implantation.

2. Preimplantation Genetic Testing for Monogenic Diseases (PGT-M)

PGT-M is used when one or both parents are carriers of a known genetic disorder, such as cystic fibrosis, sickle cell anaemia, Fanconi’s anaemia or Tay-Sachs disease. This test identifies embryos with faulty genes, allowing only healthy embryos to be selected for implantation.

3. Preimplantation Genetic Testing for Structural Rearrangements (PGT-SR)

PGT-SR is recommended for individuals with structural chromosomal rearrangements, such as translocations or inversions. These conditions can increase the risk of miscarriage or result in embryos with imbalanced genetic material.

Who Can Benefit from Embryo Testing?

Embryo genetic testing can be particularly beneficial for:

• Couples with a history of genetic disorders
• Those carrying chromosomal abnormalities
• Women over the age of 35 undergoing IVF
• Individuals who have experienced recurrent miscarriages
• Couples with previous failed IVF attempts

Advantages of Genetic Embryo Selection

1. Higher IVF Success Rates – By transferring only genetically healthy embryos, the chances of successful implantation and pregnancy are significantly improved.
2. Reduced Risk of Genetic Disorders – Parents can avoid passing on heritable conditions, ensuring a healthier baby.
3. Lower Miscarriage Rates – Many miscarriages result from chromosomal abnormalities. Genetic screening helps reduce this risk.
4. Faster Path to Parenthood – PGT can save time, costs, and emotional stress by increasing the efficiency of IVF cycles.

Limitations and Ethical Considerations

While preimplantation genetic screening is a remarkable advancement, there are some limitations to consider:

• Not a Guarantee – While PGT reduces risks, it does not guarantee a successful pregnancy.
• Cost Factor – Genetic testing adds to the overall cost of IVF treatment.
• Ethical Concerns – Some may question the moral implications of embryo selection, particularly regarding non-medical traits.

Conclusion

Preimplantation genetic testing is a game-changer for couples undergoing IVF, offering a proactive approach to selecting healthy embryos and increasing the chances of a successful pregnancy. If you’re considering preimplantation genetic testing, consult with our fertility experts at Milann Fertility to understand how it can benefit your journey to parenthood.

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Reviewed by Dr. Meghana Nyapathi - Reproductive Medicine Bengaluru, JP Nagar, HSR Layout.