Understanding PGT Results: What a Normal Result Means

Waiting for preimplantation genetic testing (PGT) results can be a time of uncertainty. You may wonder what the report will show, how to interpret the terms, and what a “normal” result really means for your embryo. This guide explains the typical structure of a PGT report, defines common terms, and offers questions to ask your clinic so you can approach the results with more confidence.

At a Glance: Key Points About PGT Results

• PGT results are reported per embryo, not per cycle.
• Terms like “euploid,” “aneuploid,” and “mosaic” describe the genetic status of an embryo.
• A “normal” result means no chromosomal abnormalities were detected by the test, but it does not guarantee pregnancy or a healthy baby.
• PGT is a screening tool, not a diagnostic test, and it has limitations.
• Your clinic will explain the results in the context of your specific situation.

What Is PGT and Why Is It Done?

PGT is a test performed on embryos created through in vitro fertilization (IVF) before transfer to the uterus. It is used to identify embryos that may have certain genetic or chromosomal issues. There are three main types:

• PGT-A (aneuploidy screening): Checks for the correct number of chromosomes. Embryos with the correct number are called “euploid,” while those with missing or extra chromosomes are “aneuploid.”
• PGT-M (monogenic disorders): Looks for specific inherited single-gene conditions, such as cystic fibrosis or sickle cell anemia.
• PGT-SR (structural rearrangements): Detects chromosomal structural changes, such as translocations, that may affect embryo development.

PGT is not for everyone. It is often recommended for certain situations, such as advanced maternal age, recurrent pregnancy loss, or a known genetic condition in the family. Your clinic will advise whether PGT is appropriate for you.

How Are PGT Results Reported?

PGT results are typically provided in a laboratory report that lists each embryo tested and its result. The report may include:

• Embryo identification number
• Type of PGT performed (e.g., PGT-A)
• Result category (e.g., euploid, aneuploid, mosaic)
• Additional notes or recommendations

Results are usually given as one of the following:

• Euploid (normal): The embryo has the expected number of chromosomes (for PGT-A) or does not carry the specific genetic variant tested (for PGT-M/SR).
• Aneuploid (abnormal): The embryo has an abnormal number of chromosomes.
• Mosaic: The embryo has a mix of normal and abnormal cells. This is a newer category, and its implications are still being studied.
• Inconclusive: The test did not yield a clear result, possibly due to technical issues or insufficient DNA.

It is important to note that PGT results are not always black and white. For example, a “normal” result in PGT-A means no chromosomal abnormalities were detected, but it does not rule out all genetic conditions or guarantee a successful pregnancy.

What Does a “Normal” Result Mean?

A normal PGT result is reassuring, but it is not a guarantee. Here’s what it does and does not mean:

• It means: The embryo appears to have the correct number of chromosomes (for PGT-A) or does not carry the specific genetic condition tested (for PGT-M/SR).
• It does not mean: The embryo is guaranteed to implant, result in a live birth, or be free of all health issues. PGT cannot detect all genetic or chromosomal abnormalities, and it does not assess the embryo’s overall viability.

In other words, a normal PGT result is a positive sign, but it is just one piece of information. Other factors, such as embryo quality, uterine environment, and overall health, also play a role.

Understanding Mosaic Results

Mosaic embryos have both normal and abnormal cells. The percentage of abnormal cells can vary, and the clinical significance is still being researched. Some clinics may consider transferring a mosaic embryo if no euploid embryos are available, but this decision is made on a case-by-case basis. It is essential to discuss the specific mosaic level and its potential implications with your clinic.

Limitations of PGT

PGT is a powerful tool, but it has limitations:

• Not diagnostic: PGT is a screening test, not a diagnostic test. It cannot detect all genetic conditions or chromosomal abnormalities.
• Technical limitations: The test may fail to amplify DNA or produce inconclusive results.
• Embryo biopsy risks: The biopsy procedure, though generally safe, may have a small risk of damaging the embryo.
• Not a guarantee: Even a normal embryo may not lead to a pregnancy due to other factors.

Understanding these limitations can help you interpret your results with realistic expectations.

Questions to Ask Your Clinic About PGT Results

When you receive your PGT report, consider asking your clinic the following questions:

• What does this result mean for my specific embryo?
• How reliable is the test for the condition we were screening for?
• If the result is mosaic, what is the percentage of abnormal cells, and what are the potential outcomes?
• Are there any additional tests or follow-up steps recommended?
• How does this result affect the decision to transfer the embryo?

These questions can help you make an informed decision about next steps.

Next Steps After Receiving PGT Results

After you receive your PGT results, your clinic will discuss the options with you. These may include:

• Transferring a euploid embryo
• Discussing the possibility of transferring a mosaic embryo (if applicable)
• Considering additional testing or consultation with a genetic counselor
• Deciding whether to freeze or discard embryos based on results

Take your time to process the information and ask for clarification if needed. Your clinic is there to support you.

Conclusion

PGT results can be complex, but understanding the basics can reduce anxiety and help you make informed decisions. Remember that a normal result is a positive sign, but it is not a guarantee. Always discuss your results with your clinic and ask questions to ensure you fully understand what they mean for your journey.

Frequently asked questions

What is the difference between PGT-A, PGT-M, and PGT-SR?

PGT-A screens for an abnormal number of chromosomes (aneuploidy). PGT-M tests for specific single-gene disorders. PGT-SR checks for structural changes in chromosomes, such as translocations.

Does a normal PGT result guarantee a healthy baby?

No. A normal PGT result means no chromosomal abnormalities were detected, but it does not guarantee pregnancy, live birth, or the absence of all health issues. PGT cannot detect all genetic conditions.

What is a mosaic embryo?

A mosaic embryo has a mix of normal and abnormal cells. The clinical significance is still being studied, and the decision to transfer a mosaic embryo is made on a case-by-case basis.

What should I do if my PGT result is inconclusive?

An inconclusive result means the test did not yield a clear answer. Your clinic may recommend repeating the test, or you may consider other options. Discuss the next steps with your clinic.

Can PGT detect all genetic disorders?

No. PGT is a screening test that can detect specific chromosomal abnormalities or single-gene disorders, but it cannot detect all genetic conditions or birth defects.

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.