When Might PGT-SR Be Discussed in an IVF Pathway?

If you or your partner has a structural chromosome rearrangement—such as a balanced translocation or inversion—you may wonder when preimplantation genetic testing for structural rearrangements (PGT-SR) might come up in an IVF pathway. PGT-SR is a technique used during IVF to screen embryos for chromosomal imbalances that can result from such rearrangements. It is not a routine test for everyone; it is typically discussed when a specific genetic situation is known or suspected. This guide explains the typical timing, the steps involved, and the questions you may want to ask your clinic.

At a glance: When PGT-SR may be considered

• After a structural chromosome rearrangement is identified in either partner.
• During genetic counseling before starting IVF.
• When planning an IVF cycle with embryo biopsy and genetic testing.
• When discussing reproductive options with a fertility specialist or geneticist.

Understanding PGT-SR

PGT-SR is one of several types of preimplantation genetic testing. It is designed to detect embryos that have an unbalanced form of a structural rearrangement. Unlike PGT-A (which screens for an abnormal number of chromosomes) or PGT-M (which tests for a specific single-gene disorder), PGT-SR focuses on the structural arrangement of chromosomes. It is not a guarantee of a healthy pregnancy or a live birth, and it is not suitable for every patient. The decision to use PGT-SR should be made in consultation with a genetics specialist and your fertility team.

When might PGT-SR be discussed?

PGT-SR is usually discussed in the following situations:

• After a genetic diagnosis: If a blood test (karyotype) has shown a structural rearrangement in you or your partner, your doctor may mention PGT-SR as an option during IVF.
• During genetic counseling: A genetic counselor can explain the risks of unbalanced chromosomes and how PGT-SR might help select embryos for transfer.
• Before starting IVF: If you are already planning IVF for other reasons, your clinic may discuss PGT-SR as an add-on test.
• After previous pregnancy loss or a child with a chromosomal imbalance: These experiences may prompt testing and discussion of PGT-SR.

The exact timing can vary. Some clinics may raise the topic during your initial consultation, while others may wait until after you have completed genetic testing. It is important to ask your clinic about their specific process.

The IVF pathway with PGT-SR: A step-by-step timeline

If PGT-SR is part of your plan, the IVF process typically follows these steps:

1. Genetic counseling and testing: You and your partner may undergo blood tests to confirm the rearrangement and understand its implications.
2. IVF cycle start: You begin ovarian stimulation and egg retrieval as in a standard IVF cycle.
3. Fertilization and embryo culture: Eggs are fertilized with sperm, and embryos are cultured for several days.
4. Embryo biopsy: A few cells are removed from each embryo, usually on day 5 or 6 (blastocyst stage).
5. Genetic analysis: The biopsied cells are sent to a genetics laboratory for PGT-SR analysis.
6. Results and transfer: Once results are available, you and your doctor discuss which embryos (if any) are suitable for transfer.

The time from biopsy to results can vary, so ask your clinic for their typical timeline. Also, note that not all embryos may be suitable for transfer, and there is no guarantee of a pregnancy.

Key considerations for international patients

If you are considering PGT in Thailand as an international patient, there are several factors to keep in mind:

• Genetic counseling: Ensure you have access to a genetic counselor who can explain the implications of your specific rearrangement.
• Laboratory accreditation: Ask about the laboratory that will perform the genetic analysis and its quality standards.
• Costs: PGT-SR adds to the cost of IVF. Ask for a detailed breakdown of fees, including biopsy, genetic testing, and any additional procedures.
• Legal and regulatory aspects: Regulations around PGT can vary by country. Confirm with your clinic what is permitted and what documentation you may need.
• Travel and accommodation: If you are traveling for treatment, plan for the time required for the IVF cycle and the waiting period for genetic results.

These are general categories; specific details should be confirmed directly with your chosen clinic.

Questions to ask your clinic about PGT-SR

Before deciding on PGT-SR, consider asking your clinic the following questions:

• What is the success rate of PGT-SR at your clinic? (Ask for their own data, not general figures.)
• How many embryos typically have unbalanced chromosomes in my situation?
• What is the turnaround time for genetic results?
• Are there any additional risks to the embryos from biopsy?
• What are the costs, and what is included?
• Who will interpret the results, and will I have a follow-up consultation?

These questions can help you make an informed decision.

Alternatives and limitations

PGT-SR is not the only option. Depending on your situation, alternatives may include:

• IVF without PGT: You may choose to transfer embryos without testing and use prenatal diagnosis (such as amniocentesis) during pregnancy.
• Using donor gametes: In some cases, using donor eggs or sperm may be considered.
• Natural conception with prenatal testing: Some couples may opt to conceive naturally and undergo prenatal testing.

PGT-SR has limitations. It cannot detect all genetic conditions, and it does not guarantee a healthy baby. The biopsy process may damage some embryos, and not all embryos will be suitable for transfer. Discuss these limitations with your team.

Next steps

If you are considering PGT-SR, your next steps may include:

1. Consult with a genetic counselor to understand your specific rearrangement.
2. Research fertility clinics that offer PGT-SR and have experience with your condition.
3. Ask for a detailed treatment plan and cost estimate.
4. Clarify any legal or regulatory questions with the clinic.
5. Plan your travel and accommodation if you are coming from abroad.

Remember, the decision to use PGT-SR is personal and should be made with professional guidance.

Frequently asked questions

Is PGT-SR the same as PGT-A?

No. PGT-A screens for an abnormal number of chromosomes (aneuploidy), while PGT-SR specifically looks for unbalanced structural rearrangements, such as translocations or inversions. They are different tests and may be used together in some cases.

How long does PGT-SR take?

The genetic analysis itself may take several days to a few weeks, depending on the laboratory. Your clinic can provide a specific timeline for your cycle.

Does PGT-SR guarantee a healthy baby?

No. PGT-SR can reduce the risk of transferring embryos with unbalanced chromosomes, but it does not guarantee a pregnancy or a healthy child. Other genetic and non-genetic factors can affect outcomes.

Can PGT-SR be done with frozen embryos?

Yes, PGT-SR can be performed on embryos that are biopsied and then frozen while awaiting results. This is a common approach.

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.