How Are PGT Results Reported by Thai Labs? A Guide for Patients

Introduction

After undergoing preimplantation genetic testing (PGT) as part of your IVF cycle in Thailand, you will receive a laboratory report detailing the genetic status of each biopsied embryo. Understanding how these results are reported and what they mean is crucial for making informed decisions with your fertility team. This guide explains the typical format of PGT reports from Thai laboratories, how to interpret common terms like euploid, aneuploid, and mosaic, and what to consider when discussing your results with your doctor.

Types of PGT and What They Test

Thai laboratories offer three main types of PGT:

• PGT-A (Aneuploidy): Screens embryos for the correct number of chromosomes (23 pairs). Aneuploidy (extra or missing chromosomes) is a common cause of implantation failure and miscarriage.
• PGT-M (Monogenic): Tests for specific single-gene disorders (e.g., cystic fibrosis, thalassemia) when one or both parents carry a known mutation.
• PGT-SR (Structural Rearrangement): Detects unbalanced chromosomal rearrangements (e.g., translocations, inversions) that can lead to abnormal embryos.

Some labs offer combined testing (e.g., PGT-A + PGT-M) from a single biopsy.

Typical Report Format

While each laboratory may have its own template, most PGT reports from Thai clinics include the following sections:

• Patient and Cycle Information: Your name, date of birth, cycle number, and date of biopsy.
• Embryo Identification: Each biopsied embryo is assigned a unique ID or number, often linked to its developmental stage (e.g., day 5 or day 6 blastocyst).
• Testing Method: The technology used (e.g., next-generation sequencing, NGS; or array comparative genomic hybridization, aCGH). NGS is now the most common method in Thailand.
• Results per Embryo: A table or list showing each embryo’s genetic status. For PGT-A, this includes the chromosome copy number (e.g., 46,XX or 46,XY for normal) and any abnormalities detected. For PGT-M, the report indicates whether the embryo carries the mutation, is unaffected, or is a carrier (if applicable). For PGT-SR, it shows whether the embryo has a balanced or unbalanced rearrangement.
• Interpretation: A summary classifying each embryo as euploid, aneuploid, or mosaic (for PGT-A). For PGT-M/SR, terms like “affected,” “unaffected,” or “carrier” may be used.
• Quality Metrics: Some reports include DNA amplification success, contamination checks, and confidence scores.
• Recommendations: The lab may suggest genetic counseling or further testing (e.g., confirmatory prenatal diagnosis if pregnancy occurs).

Interpreting PGT-A Results: Euploid, Aneuploid, Mosaic

PGT-A results fall into three main categories:

• Euploid: The embryo has the expected number of chromosomes (46,XX or 46,XY). These embryos have the highest chance of implantation and developing into a healthy baby, but they are not guaranteed to result in a live birth.
• Aneuploid: The embryo has extra or missing chromosomes (e.g., trisomy 21, monosomy X). These embryos are unlikely to implant or will likely miscarry; they are generally not recommended for transfer.
• Mosaic: The embryo contains a mixture of euploid and aneuploid cells. Mosaicism is reported as a percentage (e.g., 20% mosaic). The clinical significance depends on the level and type of mosaicism. Some mosaic embryos may still result in a healthy baby, but the risk of abnormalities is higher. Discuss with your doctor whether a mosaic embryo is suitable for transfer.

Note: PGT-A cannot detect all genetic conditions (e.g., microdeletions, uniparental disomy) and has a small error rate (typically <5%).

Interpreting PGT-M and PGT-SR Results

For PGT-M, the report will indicate whether the embryo inherited the mutation(s) tested. Results may be:

• Unaffected: The embryo does not carry the mutation.
• Carrier: The embryo carries one copy of a recessive mutation but is not expected to develop the disease.
• Affected: The embryo carries the mutation(s) and is expected to develop the disorder.

For PGT-SR, the report will state whether the embryo has a balanced (normal or carrier) or unbalanced (abnormal) chromosomal rearrangement. Balanced carriers are generally healthy but may have fertility issues later.

Turnaround Time

The time from embryo biopsy to receiving results varies by laboratory and testing complexity. For PGT-A, results are typically available within 1–2 weeks. PGT-M and PGT-SR may take longer (2–4 weeks) because they require custom probe development or family studies. Your clinic will provide an estimated timeline. Note that turnaround times can be affected by sample transport, lab workload, and the need for repeat testing.

Discussing Results with Your Doctor

Once you receive your PGT report, schedule a consultation with your fertility specialist and/or genetic counselor. Key points to discuss:

• Which embryos are suitable for transfer: Euploid embryos are prioritized. For mosaic or carrier embryos, your doctor will explain the risks and success rates based on your specific situation.
• Number of embryos available: PGT can reduce the number of transferable embryos, especially for older patients or those with genetic conditions. Discuss your options if few or no euploid embryos are available.
• Limitations of testing: PGT is a screening tool, not a diagnostic test. It cannot guarantee a healthy baby or prevent all genetic disorders. Confirmatory prenatal testing (e.g., chorionic villus sampling or amniocentesis) is recommended if pregnancy occurs.
• Next steps: Your doctor will advise on whether to proceed with a frozen embryo transfer (FET) in a subsequent cycle, or if additional testing (e.g., re-biopsy for inconclusive results) is needed.

Alternatives and Limitations

PGT is not suitable for everyone. Alternatives include:

• No testing: Transferring embryos based on morphology alone.
• Prenatal diagnosis: Testing during pregnancy (e.g., NIPT, amniocentesis).
• Donor gametes: Using donor eggs or sperm to avoid genetic risks.

Limitations of PGT include:

• Not all embryos can be biopsied (e.g., poor-quality blastocysts).
• Mosaicism can lead to false-positive or false-negative results.
• PGT does not eliminate the risk of miscarriage or birth defects.

Questions to Ask Your Clinic

Before proceeding with PGT, consider asking your Thai clinic:

• Which laboratory will perform the testing? Is it accredited (e.g., ISO 15189)?
• What is the typical turnaround time for results?
• How are mosaic results reported and managed?
• What is the policy for inconclusive or failed results?
• Are genetic counseling services available?

Conclusion

PGT results from Thai laboratories are reported in a detailed, standardized format that helps you and your doctor make informed decisions about embryo transfer. Understanding terms like euploid, aneuploid, and mosaic, as well as the limitations of testing, is essential. Always discuss your results with a qualified professional who can interpret them in the context of your medical history and treatment plan.

Frequently asked questions

What does a euploid embryo mean?

A euploid embryo has the correct number of chromosomes (46,XX or 46,XY). It has the highest chance of implantation and developing into a healthy baby, but it is not a guarantee of pregnancy or live birth.

Can a mosaic embryo be transferred?

In some cases, mosaic embryos may be considered for transfer if no euploid embryos are available. The decision depends on the level and type of mosaicism, and should be made after thorough genetic counseling with your doctor.

How long does it take to get PGT results in Thailand?

Turnaround time varies by lab and test type. PGT-A results typically take 1–2 weeks, while PGT-M and PGT-SR may take 2–4 weeks. Your clinic will provide an estimated timeline.

Is PGT 100% accurate?

No, PGT has a small error rate (typically <5%) due to factors like mosaicism or technical limitations. Confirmatory prenatal testing is recommended if pregnancy occurs.

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.