Understanding the Risks of PGT for Embryos in Thailand

Preimplantation genetic testing (PGT) is a procedure used during IVF to screen embryos for genetic abnormalities before transfer. While PGT can provide valuable information, it is not without risks. Understanding these risks helps you make an informed decision. This article explains the main risks associated with PGT for embryos in Thailand, including embryo damage, mosaicism, and false results.

At a Glance: Key Risks of PGT

• Embryo damage: Biopsy may harm the embryo, though the risk is low.
• Mosaicism: Results may not reflect all cells in the embryo.
• False positives/negatives: Testing errors can lead to discarding healthy embryos or transferring affected ones.
• Inconclusive results: Some embryos yield no clear diagnosis.
• No guarantee of pregnancy or live birth: PGT does not ensure a successful outcome.

What Is PGT and Why Is It Used?

PGT involves taking a few cells from an embryo (biopsy) to test for specific genetic conditions. There are three main types:

• PGT-A (aneuploidy): Screens for abnormal chromosome numbers, which can cause miscarriage or conditions like Down syndrome.
• PGT-M (monogenic): Tests for single-gene disorders such as cystic fibrosis or sickle cell disease.
• PGT-SR (structural rearrangement): Detects chromosomal rearrangements like translocations that may affect embryo development.

PGT is typically recommended for couples with known genetic risks, advanced maternal age, recurrent miscarriage, or previous IVF failures. However, it is not a routine procedure for all IVF patients.

Potential Risks of Embryo Biopsy

Embryo Damage

During biopsy, a laser or mechanical method is used to remove cells from the embryo. While embryologists are highly skilled, there is a small risk of damaging the embryo. Studies suggest that the risk of embryo loss due to biopsy is low (around 1-2%), but it is not zero. The embryo’s survival depends on its quality and the expertise of the laboratory.

Impact on Embryo Development

Some research indicates that biopsy may slightly reduce the embryo’s implantation potential, though evidence is mixed. The removal of cells could affect the embryo’s ability to hatch or implant in the uterus. However, many clinics report similar pregnancy rates after PGT compared to IVF without testing.

Mosaicism: When Results Are Not Clear-Cut

Mosaicism occurs when an embryo has both normal and abnormal cells. A biopsy samples only a few cells, which may not represent the entire embryo. For example, if the biopsied cells are normal but other cells are abnormal, the test may incorrectly report the embryo as normal (false negative). Conversely, if biopsied cells are abnormal but most cells are normal, the embryo may be discarded unnecessarily (false positive).

Mosaic embryos can sometimes develop into healthy babies, but the risk of genetic disorders is higher. Clinics may offer additional testing or counseling for mosaic results.

False Positives and False Negatives

No genetic test is 100% accurate. PGT can produce:

• False positive: The test indicates an abnormality when the embryo is actually normal. This can lead to discarding a healthy embryo.
• False negative: The test indicates normal when the embryo has an abnormality. This could result in transferring an affected embryo.

The accuracy of PGT depends on the laboratory’s techniques, the number of cells tested, and the specific condition being screened. For PGT-A, false positive rates are estimated at 2-5%, while false negatives are rarer but possible. Confirmatory testing (e.g., prenatal diagnosis) is recommended after pregnancy.

Inconclusive Results and Embryo Wastage

Sometimes, the biopsy sample does not yield enough DNA for analysis, or the results are ambiguous. In such cases, the embryo may be considered untestable, and you may need to decide whether to transfer it without genetic information or discard it. This can reduce the number of viable embryos available for transfer.

Limitations of PGT: What It Cannot Do

PGT is a screening tool, not a guarantee. It cannot:

• Ensure pregnancy or live birth.
• Prevent all genetic disorders (only those tested).
• Predict the child’s future health, intelligence, or physical traits.
• Replace prenatal testing during pregnancy.

Additionally, PGT does not eliminate the risk of miscarriage or birth defects unrelated to the tested condition.

Questions to Ask Your Clinic About PGT Risks

Before proceeding with PGT in Thailand, consider asking your clinic:

• What is your experience with embryo biopsy? How many procedures have you performed?
• What is your rate of embryo damage or loss after biopsy?
• How do you handle mosaic results? Do you offer additional testing?
• What is the accuracy of your PGT for the specific condition we are testing?
• What are the costs involved, and what happens if results are inconclusive?

Next Steps: Making an Informed Decision

• Consult with a genetic counselor to understand your specific risks.
• Discuss the benefits and limitations of PGT with your fertility specialist.
• Confirm the laboratory’s accreditation and quality standards.
• Consider the emotional and financial costs of PGT versus the potential benefits.

For more information, see our PGT in Thailand guide, patient guides, and frequently asked questions.

Frequently asked questions

Can PGT damage the embryo?

Yes, there is a small risk of embryo damage during biopsy, but it is low (around 1-2% in experienced labs). The embryo may also have slightly reduced implantation potential, though many clinics report similar pregnancy rates.

What is mosaicism in PGT?

Mosaicism means an embryo has both normal and abnormal cells. Since biopsy samples only a few cells, the test may not reflect the whole embryo. Mosaic embryos can sometimes develop normally, but there is a higher risk of genetic disorders.

How accurate is PGT?

PGT is highly accurate but not 100%. False positives (abnormal result in a normal embryo) and false negatives (normal result in an abnormal embryo) can occur. Confirmatory prenatal testing is recommended after pregnancy.

Does PGT guarantee a healthy baby?

No. PGT only screens for specific genetic conditions and does not prevent all birth defects or guarantee pregnancy, live birth, or the child's future health.

What happens if PGT results are inconclusive?

If the biopsy sample does not provide enough DNA or results are ambiguous, the embryo may be considered untestable. You may choose to transfer it without genetic information or discard it, depending on clinic policy and your preferences.

Continue your research

• PGT in Thailand overview
• PGT and IVF guides
• Frequently asked questions

Medical information notice: This article is educational and does not replace individual assessment, diagnosis, genetic counselling or treatment advice from a licensed clinician. Provider services, availability, fees and policies should be verified directly before booking.