At a glance
PGT-SR is a targeted embryo testing option for people who carry a balanced translocation or another structural rearrangement. This guide explains what it can and cannot tell you, how it differs from PGT-A and PGT-M, and what to confirm with a clinic in Thailand.
PGT-SR (preimplantation genetic testing for structural rearrangements) is a targeted form of embryo testing for people who carry a known structural chromosome rearrangement, such as a balanced translocation, or who have a history of recurrent pregnancy loss linked to such a rearrangement. It looks at the specific chromosomes involved in that rearrangement rather than screening the whole genome broadly. It is not a guarantee of pregnancy, and it is not the right test for everyone. Whether it is appropriate depends on your own genetic findings, your history and your clinic’s assessment.
At a glance
- What it is: embryo testing aimed at a rearrangement that has already been identified in a parent.
- Who it may be relevant for: confirmed carriers of a balanced translocation or similar structural rearrangement, sometimes alongside recurrent miscarriage.
- How it differs: PGT-A screens for chromosome number across the genome; PGT-M targets a single-gene condition; PGT-SR targets a known structural rearrangement.
- What it cannot do: it cannot guarantee a healthy pregnancy, a live birth or a healthy child, and it does not replace diagnostic testing in pregnancy.
- What to confirm: whether your specific rearrangement is testable, how the lab validates the test, costs, timelines and what happens to embryos with unclear results.
What PGT-SR actually tests for
Chromosomes normally come in pairs. In a balanced structural rearrangement, chromosome material is rearranged but no significant amount is gained or lost. The person carrying it is usually healthy, but the rearrangement can affect how chromosomes separate during egg or sperm formation. That can lead to embryos with extra or missing chromosome material, which may fail to implant, end in miscarriage, or in some cases lead to a child with health or developmental concerns.
PGT-SR is designed to examine the chromosomes involved in that known rearrangement in embryos created through IVF. The goal is to identify embryos that have not inherited an unbalanced form of the rearrangement, so that those embryos can be considered for transfer. It is a selection tool, not a treatment for the rearrangement itself.
PGT-SR compared with PGT-A and PGT-M
These three tests are often mentioned together, but they answer different questions. The right choice depends on the indication, which is why a genetic consultation usually comes before a testing decision.
| Test | Main indication | What it looks at | Typical limitation |
|---|---|---|---|
| PGT-A | Screening for chromosome number in embryos, often related to maternal age or repeated IVF failure | Chromosome number across the genome | Does not target a specific familial rearrangement or a single-gene condition |
| PGT-M | A known single-gene (monogenic) condition in the family | The specific gene and mutation | Requires a validated, condition-specific test |
| PGT-SR | A confirmed structural rearrangement such as a balanced translocation | The chromosomes involved in that rearrangement | Needs prior confirmation of the rearrangement and lab validation |
In some situations a clinic may discuss combining tests, for example PGT-SR with PGT-A, or PGT-M with PGT-A. Whether that is useful, and how the results are interpreted together, is a clinical and laboratory decision rather than a standard package.
Who might consider PGT-SR
PGT-SR is usually discussed when a structural rearrangement has already been identified, often after genetic testing prompted by recurrent miscarriage, a previous pregnancy or child with a chromosome condition, or a family history. Recurrent miscarriage can have many causes, and a chromosome rearrangement in one partner is only one possible explanation. Not everyone with a translocation needs PGT-SR, and not everyone with recurrent miscarriage has a translocation.
A genetic counsellor or clinical geneticist can help you understand your own karyotype or microarray result, the estimated chance of an unbalanced pregnancy, and whether embryo testing would meaningfully change your options. This is a personal risk assessment, not a general rule.
How the process usually works
- Confirm the diagnosis. Your rearrangement should be documented with the correct test, such as a karyotype, and reviewed by a genetics professional.
- Check test feasibility. The laboratory confirms it can design and validate a PGT-SR test for your specific rearrangement. Some rearrangements are more straightforward to test than others.
- IVF cycle. Eggs are collected and fertilised, and embryos are cultured to a suitable stage for biopsy.
- Embryo biopsy and testing. A small number of cells are removed and analysed. The exact method and timing are laboratory-specific.
- Results and counselling. Results are discussed with you, including any embryos with unclear or inconclusive findings.
- Transfer and follow-up. If you proceed, an embryo is transferred, and pregnancy follow-up may include diagnostic testing such as chorionic villus sampling or amniocentesis, because PGT is a screening step rather than a diagnosis.
What results can and cannot tell you
A PGT-SR result is a laboratory estimate about the chromosomes tested in the biopsied cells. It can indicate whether an embryo appears to carry an unbalanced form of the rearrangement. It cannot tell you that an embryo is completely free of all genetic issues, that implantation will occur, or that a pregnancy will result in a healthy child. Mosaic results, where cells differ, and inconclusive results can occur, and clinics handle these differently.
Because of these limits, many clinics recommend confirmatory prenatal testing during any pregnancy achieved after PGT. This is a discussion to have with your obstetric team.
Alternatives and complementary options
- Expectant management or natural conception with prenatal diagnosis, depending on your personal risk and preferences.
- Donor gametes (eggs or sperm), which may remove the rearrangement from the equation but raise separate considerations.
- PGT-A if the main concern is chromosome number rather than a specific rearrangement.
- Preimplantation genetic testing for a single-gene condition (PGT-M) if there is also a monogenic condition in the family.
- Genetic counselling alone, which can help you weigh risks and options without embryo testing.
None of these is universally better. The right path depends on your genetics, your history, your values and what a clinic can offer.
Questions to ask a clinic in Thailand
- Has your laboratory validated a PGT-SR test for my specific rearrangement, and what is the validation process?
- What proportion of embryos typically give a conclusive result, and how are inconclusive or mosaic results handled?
- Do you recommend combining PGT-SR with PGT-A, and why or why not in my case?
- What are the total costs, including genetic counselling, IVF, biopsy, testing, storage and transfer, and what is not included?
- What are the timelines from consultation to transfer, and what could change them?
- What prenatal follow-up do you recommend if a pregnancy occurs?
- What are your arrangements for shipping or storing samples, and how do you communicate results internationally?
- What legal or consent requirements apply to me as an international patient, and who can confirm them?
Practical next steps
- Gather your genetic test reports and any relevant medical history.
- Speak with a genetic counsellor or clinical geneticist about your specific rearrangement and your options.
- Shortlist clinics and ask the questions above, ideally in writing.
- Confirm costs, timelines, travel requirements and legal or consent steps directly with the clinic and, where relevant, official authorities.
- Decide with your clinical team whether PGT-SR is appropriate for you, and what you would do with different results.
For more background, see our PGT in Thailand overview and the related guides. If you have a specific question, the FAQ may help.
Frequently asked questions
Is PGT-SR the same as PGT-A?
No. PGT-A screens for chromosome number across the genome, often in relation to maternal age or repeated IVF failure. PGT-SR targets a specific structural rearrangement that has already been identified in a parent, such as a balanced translocation. They answer different questions and may sometimes be used together, depending on the clinical situation.
Does PGT-SR guarantee a healthy baby?
No. PGT-SR is a screening test on a small number of embryo cells. It can reduce the chance of transferring an embryo with an unbalanced form of a known rearrangement, but it cannot guarantee implantation, pregnancy, live birth or a child without health concerns. Confirmatory prenatal testing is often recommended during pregnancy.
Can I have PGT-SR if I have recurrent miscarriages but no known translocation?
PGT-SR is designed for a known structural rearrangement. If you have recurrent miscarriage without a confirmed rearrangement, your clinic would first investigate possible causes. Depending on the findings, other options such as PGT-A or further genetic assessment may be discussed. This is an individual clinical decision.
What should I confirm before travelling to Thailand for PGT-SR?
Confirm that the laboratory can validate a test for your specific rearrangement, the total cost and what it includes, the expected timeline, how results are communicated, consent and legal requirements for international patients, and what prenatal follow-up is advised. Ask for these details in writing and verify any legal or entry requirements with official sources.
What happens if my embryos have inconclusive PGT-SR results?
Inconclusive or mosaic results can occur. How they are handled varies by clinic and laboratory. Some may recommend re-biopsy, additional testing or a different transfer strategy. Ask your clinic in advance how they manage unclear results so you can decide what you would prefer.
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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.
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