What is PGT and why is it used with IVF?
Preimplantation genetic testing (PGT) is a set of techniques used to examine embryos created through in vitro fertilization (IVF) for specific genetic conditions before a pregnancy is established. The goal is to provide information that may help you and your doctor decide which embryos to consider for transfer. PGT is not a guarantee of a healthy baby or a successful pregnancy, and it is not necessary for every patient. It is an optional step that may be recommended based on your medical history, age, or family genetic risks.
In Thailand, many IVF clinics offer PGT as part of their services. If you are considering IVF with genetic testing, understanding the types of PGT, the process, and the limitations can help you make an informed decision.
At a glance: key points about PGT
- PGT is performed on embryos before transfer to screen for chromosomal abnormalities or specific genetic disorders.
- There are three main types: PGT-A (aneuploidy), PGT-M (monogenic disorders), and PGT-SR (structural rearrangements).
- PGT requires IVF, embryo biopsy, and often a genetic laboratory with specialized expertise.
- Results are not always conclusive, and not all embryos may be suitable for transfer.
- Costs, legal considerations, and availability vary by clinic and country.
Types of PGT: PGT-A, PGT-M, and PGT-SR
PGT-A (aneuploidy screening)
PGT-A checks embryos for the correct number of chromosomes. Aneuploidy—having too many or too few chromosomes—is a common cause of implantation failure and miscarriage. PGT-A is often considered for women of advanced maternal age, couples with recurrent pregnancy loss, or those who have had multiple failed IVF cycles. However, it does not detect all genetic abnormalities, and some embryos with abnormal cells may still lead to a healthy birth.
PGT-M (monogenic disorders)
PGT-M is used when one or both partners carry a specific single-gene disorder, such as cystic fibrosis, sickle cell anemia, or Huntington’s disease. This test looks for the presence of that specific genetic mutation in embryos. PGT-M requires a prior genetic workup of the parents to design a personalized test. It is not available for all genetic conditions, and the accuracy depends on the quality of the family genetic information.
PGT-SR (structural rearrangements)
PGT-SR is for individuals who have structural changes in their chromosomes, such as translocations or inversions. These rearrangements can lead to unbalanced chromosomes in embryos, increasing the risk of miscarriage or birth defects. PGT-SR helps identify embryos with a normal or balanced chromosomal arrangement. As with other types, it does not guarantee a successful pregnancy.
How PGT is performed in Thailand: the process
The PGT process is integrated into an IVF cycle. Here is a general step-by-step overview, though exact protocols may vary by clinic:
- Ovarian stimulation: You take fertility medications to stimulate your ovaries to produce multiple eggs.
- Egg retrieval: Eggs are collected through a minor surgical procedure.
- Fertilization: Eggs are fertilized with sperm in the laboratory to create embryos.
- Embryo culture: Embryos are grown in the lab for several days, typically until the blastocyst stage (day 5 or 6).
- Biopsy: A few cells are removed from each embryo. The biopsy is performed by an embryologist using specialized equipment.
- Genetic analysis: The biopsied cells are sent to a genetic laboratory for testing. The type of test depends on your situation.
- Embryo transfer: After results are available, a suitable embryo may be selected for transfer. Unused embryos may be frozen for future use.
The entire process from stimulation to transfer can take several weeks, but the exact timeline depends on your individual treatment plan and the clinic’s schedule.
What do PGT results mean?
PGT results are reported as normal (euploid), abnormal (aneuploid), or inconclusive. A normal result means that the tested cells had the expected number of chromosomes or did not show the specific genetic mutation. An abnormal result indicates a potential issue, but it does not always mean the embryo cannot develop into a healthy baby. Inconclusive results may occur if the biopsy sample was insufficient or the analysis failed.
It is important to understand that PGT examines only a few cells from the embryo, which may not represent the entire embryo. Also, PGT cannot detect all genetic conditions, and it does not eliminate the risk of birth defects or developmental disorders. Your doctor will interpret the results in the context of your medical history and discuss the options.
Who might consider PGT?
PGT may be considered in the following situations, but it is not a one-size-fits-all recommendation:
- Women over a certain age (often 35 or older, but this varies by clinic and country).
- Couples with a known genetic disorder in the family.
- Individuals with a history of recurrent pregnancy loss or implantation failure.
- Couples with a chromosomal rearrangement.
- Those who want to reduce the risk of passing on a specific genetic condition.
However, PGT is not recommended for everyone. For some patients, the added cost and time may not provide significant benefit. Your fertility specialist can help you weigh the pros and cons based on your specific situation.
Alternatives to PGT
If you are considering genetic testing, there are alternatives to PGT that you may discuss with your doctor:
- Prenatal testing: Tests such as chorionic villus sampling (CVS) or amniocentesis can be done during pregnancy to check for genetic conditions. These tests carry a small risk of miscarriage.
- Carrier screening: Before IVF, you and your partner can undergo carrier screening to identify if you carry genes for certain disorders. This can help you decide whether PGT is needed.
- Donor eggs or sperm: Using donor gametes may reduce the risk of passing on a genetic condition, but this is a personal decision with its own considerations.
Each option has benefits and limitations, and the right choice depends on your medical history, values, and goals.
Questions to ask your clinic about PGT in Thailand
When considering PGT in Thailand, it is essential to ask specific questions to understand what is offered and what to expect. Here are some questions to consider:
- What types of PGT do you offer (PGT-A, PGT-M, PGT-SR)?
- How many embryos typically reach the biopsy stage?
- What is the laboratory’s experience with genetic testing?
- How long does it take to receive results?
- What are the costs for PGT, and what is included?
- Are there any legal or regulatory considerations for PGT in Thailand?
- How are inconclusive results handled?
- What is the policy on embryo freezing and storage?
Asking these questions can help you make an informed decision and set realistic expectations.
Next steps: making your decision
If you are considering PGT with IVF in Thailand, here is a simple checklist to guide you:
- Consult with a fertility specialist to review your medical history and discuss whether PGT is appropriate.
- If PGT is recommended, ask for a detailed explanation of the process, risks, and costs.
- Consider genetic counseling to understand the implications of testing and results.
- Verify the clinic’s laboratory credentials and experience with PGT.
- Clarify all costs, including biopsy, genetic analysis, and embryo storage.
- Plan for the timeline, including any travel arrangements if you are coming from abroad.
Remember, PGT is a personal choice. Take the time to gather information and ask questions until you feel comfortable with your decision.
Frequently asked questions
Is PGT mandatory for IVF in Thailand?
No, PGT is not mandatory for IVF in Thailand. It is an optional test that may be recommended based on your medical history, age, or genetic risks. Your doctor will discuss whether PGT is appropriate for you.
What is the difference between PGT-A and PGT-M?
PGT-A screens embryos for chromosomal abnormalities (aneuploidy), while PGT-M tests for specific single-gene disorders when parents are known carriers. PGT-M requires a prior genetic workup to design a personalized test.
Can PGT guarantee a healthy baby?
No, PGT cannot guarantee a healthy baby. It reduces the risk of transferring embryos with certain genetic issues, but it does not detect all conditions, and there is still a chance of birth defects or developmental problems.
How long does PGT take in Thailand?
The PGT process adds time to an IVF cycle, typically a few weeks for embryo culture and genetic analysis. The exact timeline varies by clinic and the type of test, so it is best to ask your clinic for a specific schedule.
Are there any risks associated with PGT?
The embryo biopsy is a delicate procedure, but it is generally considered safe. There is a small risk of embryo damage, and some embryos may not survive the biopsy or freezing process. Your doctor will explain the risks in detail.
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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.