Mosaic Embryo Results in Thailand: What They Mean for International Patients

A mosaic embryo result means the PGT sample showed a mixture of cells with typical chromosome patterns and cells with atypical patterns. It is not a simple positive or negative. Mosaicism exists on a spectrum, and the laboratory report usually describes the percentage of atypical cells and the type of chromosome change. Thai clinics vary in how they counsel international patients about these results. Some may discuss transfer, some may recommend further review, and some may suggest a different embryo. The right next step depends on your full clinical picture, the specific mosaic finding, and the clinic’s own laboratory and counseling protocols. This guide explains the categories and the questions that help you make an informed decision.

At a glance

• A mosaic result is a spectrum finding, not a yes-or-no diagnosis.
• Reports usually include the percentage of atypical cells and whether the change is a full chromosome gain or loss, a segment, or a mix.
• Lower-level mosaicism is often discussed differently from higher-level mosaicism, but thresholds and terminology can differ between laboratories.
• Thai clinics may have different counseling approaches, so ask how your clinic classifies and reports mosaicism.
• Transfer decisions are individual and depend on your history, the specific embryo, and what your clinic can support.
• No PGT result can guarantee a healthy pregnancy or child.

What a mosaic PGT result actually means

Preimplantation genetic testing for aneuploidy (PGT-A) examines a small sample of cells from an embryo. In a typical result, the report describes whether the tested cells showed a normal number of chromosomes (euploid) or an abnormal number (aneuploid). A mosaic result falls between these two categories: some tested cells appear euploid and some appear aneuploid.

Mosaicism can arise during early embryo development. It does not necessarily mean the whole embryo is affected, and it does not predict with certainty how the embryo will develop. The laboratory report is a snapshot from a small sample, not a complete map of every cell.

PGT-M (for monogenic conditions) and PGT-SR (for structural rearrangements) are different tests with different purposes. A mosaic finding on a PGT-A report is not the same as a PGT-M or PGT-SR result. If you are unsure which test was used, ask your clinic to clarify before interpreting the result.

How mosaic results are classified

Laboratories use different systems, but most mosaic reports include some combination of the following information. The exact terms and thresholds can vary, so always ask your clinic to explain the specific language on your report.

Report element	What it usually describes	Why it matters for counseling
Mosaic level or percentage	The estimated proportion of cells with an atypical chromosome pattern	Lower and higher levels may be discussed differently, but there is no universal cutoff that applies to every clinic or every chromosome
Chromosome involved	Which chromosome or chromosomes showed the mosaic finding	Some chromosomes are associated with different counseling considerations than others
Type of change	Full chromosome gain or loss, a segmental change, or a combination	Segmental and full-chromosome findings may be reported and interpreted differently
Number of cells analyzed	How many cells were examined in the sample	A small sample size can affect how confidently a mosaic result can be interpreted
Laboratory comments	Any notes about the finding, limitations, or recommendations	These comments often contain the most practical guidance for your clinic

Some laboratories use categories such as low-level, high-level, or a specific percentage range. Others may report a mosaic finding without a precise percentage. If your report uses a term you do not recognize, ask your clinic for a plain-language explanation.

Why Thai clinics may counsel mosaic results differently

Thailand has many IVF clinics, and each may have its own approach to mosaic embryo counseling. Differences can include:

• Which laboratory performs the PGT testing and how that laboratory defines and reports mosaicism.
• Whether the clinic has an internal policy on transferring mosaic embryos and at what mosaic level.
• How the clinic weighs the mosaic finding against other factors such as your age, embryo quality, and previous cycles.
• Whether the clinic offers additional counseling, genetic counseling, or a review of the raw data.
• How the clinic communicates uncertainty and what it recommends when evidence is limited.

Because these approaches vary, a mosaic result that one clinic describes as transferable may be described differently at another. This does not necessarily mean one clinic is right and another is wrong. It often reflects different laboratory protocols, different interpretations of the same evidence, and different clinical policies.

For international patients, it can help to ask for the clinic’s written policy on mosaic embryos before you travel or before you make a transfer decision. If the clinic does not have a written policy, ask how the decision is typically made and who is involved.

What a mosaic result does not tell you

A mosaic PGT result cannot tell you with certainty:

• Whether the embryo will implant.
• Whether a pregnancy would continue.
• Whether a child would be born healthy.
• Whether the mosaic finding is confined to the placenta or affects the fetus.
• Whether another embryo from the same cycle would have a different result.

PGT is a screening test, not a diagnostic test for every cell of the embryo. It can reduce uncertainty in some situations, but it cannot eliminate it. This is one reason why mosaic counseling focuses on probabilities, trade-offs, and your individual priorities rather than guarantees.

Questions to ask your Thai clinic about a mosaic result

These questions can help you understand your clinic’s approach and make a more informed decision. You may want to ask them in writing so you have a record of the answers.

1. Which laboratory performed the PGT, and how does that laboratory define and report mosaicism?
2. What is the exact mosaic level or percentage on my report, and what does that mean in plain language?
3. Which chromosome or chromosomes are involved, and does that change the counseling?
4. How many cells were analyzed, and how confident is the laboratory in the result?
5. Does the clinic have a policy or guideline for transferring mosaic embryos? If so, what is it?
6. What are the possible next steps if we decide not to transfer this embryo?
7. Are there additional tests or counseling options that could provide more information?
8. How does this mosaic result fit with my overall history and other embryos from this cycle?
9. What would you recommend if this were your own embryo, and why?
10. What follow-up or monitoring would you recommend if we proceed with transfer?

If you are working with a clinic in Thailand from another country, also ask how communication will be handled, who your main contact will be, and how you will receive updated reports or recommendations.

Decision points for international patients

After receiving a mosaic result, you may face several decisions. There is rarely a single correct path, and the best choice depends on your circumstances.

Transfer the mosaic embryo

Some patients and clinics decide to transfer a mosaic embryo after weighing the alternatives. This decision may be influenced by the mosaic level, the chromosome involved, the number of other available embryos, your age, your history, and your willingness to accept uncertainty. If you choose this path, ask your clinic what monitoring or follow-up they recommend.

Choose another embryo

If you have other embryos that are not mosaic, you and your clinic may discuss prioritizing those first. This is a common consideration, but it depends on how many embryos you have and their individual results.

Consider another cycle

Some patients consider another IVF cycle to try to obtain additional embryos. This is a significant decision with its own medical, emotional, and practical considerations. Ask your clinic how another cycle might be approached and what factors would be considered.

Seek a second opinion

If you are unsure about your clinic’s interpretation, you may wish to seek a second opinion from another qualified professional. A second opinion can help you understand the range of views on mosaic embryos, but it may also reflect the same uncertainties. Ask for the raw data or a detailed report if you want another professional to review the finding.

What to confirm before you travel or decide

If you are an international patient planning to travel to Thailand for a transfer or consultation, confirm the following with your clinic:

• How the clinic will communicate the mosaic result and any recommendations.
• Whether a consultation can be done remotely before travel.
• What documents or records the clinic needs from you, and how to send them securely.
• What the clinic’s policy is on mosaic embryo transfer, including any consent process.
• What follow-up care is available after transfer, and how it can be coordinated with your home clinic.
• What costs are associated with the consultation, transfer, and any additional testing, and how payment is handled.
• Whether there are any legal or regulatory considerations for your situation, and who can confirm them.

Because policies and requirements can change, always confirm current details directly with the clinic and, where relevant, with the appropriate authorities. This guide does not provide legal, financial, or medical advice for your individual situation.

Next steps

Receiving a mosaic result can feel uncertain. A practical next step is to gather clear information from your clinic and write down your questions before your next conversation. Ask for the specific details of your report, the clinic’s policy, and the reasoning behind any recommendation. If you are considering transfer, ask what follow-up would be recommended. If you are considering another option, ask what that process would involve. You do not have to decide immediately, and you can take time to review the information with people you trust.

For more general information about PGT in Thailand, see our PGT in Thailand guide. You can also browse our guides and FAQ for related topics.

Frequently asked questions

Does a mosaic embryo result mean the embryo is abnormal?

A mosaic result means the tested sample contained a mix of cells with typical and atypical chromosome patterns. It is not the same as a uniformly abnormal result, and it does not predict with certainty how the embryo will develop. The meaning depends on the specific finding, the laboratory's definitions, and your clinic's interpretation.

Can a mosaic embryo be transferred in Thailand?

Some Thai clinics may offer transfer of mosaic embryos, while others may not, and policies can vary. There is no single national rule that applies to every clinic or every mosaic finding. Ask your clinic directly about its policy, how it makes transfer decisions, and what consent or counseling it requires.

What is the difference between low-level and high-level mosaicism?

Laboratories may use different thresholds to describe mosaic levels. In general, a lower percentage of atypical cells may be discussed differently from a higher percentage, but there is no universal cutoff that applies to all chromosomes or all clinics. Ask your clinic to explain the specific level on your report and how it affects their counseling.

Should I get a second opinion on my mosaic result?

A second opinion can be helpful if you want another professional's perspective on the report or the clinic's recommendation. It may not resolve all uncertainty, because mosaic interpretation involves judgment and varies between laboratories and clinics. If you seek a second opinion, ask your clinic for the detailed report or raw data that the reviewer would need.

Does a mosaic result affect future IVF cycles?

A mosaic result in one embryo does not necessarily predict the results of a future cycle. Mosaicism can vary between embryos and between cycles. If you are considering another cycle, ask your clinic how they would approach it and what factors they would consider based on your history.

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.