PGT — Preimplantation Genetic Test

What this investigation entails

PGT, or preimplantation genetic testing, is a set of genetic tests performed on embryos obtained by in vitro fertilization, prior to embryo transfer. The investigation involves the biopsy of some embryonic cells and their genetic analysis, with the aim of identifying certain genetic or chromosomal abnormalities, depending on the medical indication. Current terminology includes PGT-M for monogenic diseases, PGT-SR for structural chromosomal rearrangements, and PGT-A for aneuploids.

When is it recommended to schedule

PGT may be considered when there is a known risk of transmission of a genetic disease, when one partner is a carrier of a mutation or structural chromosomal abnormality, or when the doctor recommends further genetic evaluation as part of IVF treatment. Clinical evaluation and genetic counseling are essential prior to testing to clarify the indication, benefits, limits and implications of the result.

Services offered in the CMIB

Advice on Preimplantation Genetic Testing Options
Evaluation of medical indication in the context of IVF treatment
Coordination of the steps required for embryo testing
Interpretation of the result in clinical and genetic context
Medical guidance for the next steps of the procedure

PGT is used in reproductive medicine to provide genetic information about embryos before transfer. The choice of the type of PGT depends on the goal pursued and the history of the couple or patient. Thus, PGT-M is used for the detection of known monogenic diseases, PGT-SR for structural chromosomal rearrangements, and PGT-A for the evaluation of aneuploidy.

It is important to understand that PGT does not completely replace the subsequent prenatal evaluation and does not guarantee the achievement of a pregnancy or the birth of a healthy baby. ACOG emphasizes that preimplantation genetic testing has limits, including the risk of false positive or false negative results and the fact that a normal result does not rule out all possible genetic conditions.

For an informed decision, it is important to follow a few essential steps:

Let's understand the type of recommended PGT and its purpose.
Let's evaluate, together with the specialist doctor and the geneticist, the reproductive and family history.
Let's know the limits of testing and what the result may or may not show.
Let's interpret the result in the context of the entire IVF process.
Let's determine the further conduct according to the medical recommendation.

1.PGT is performed only in conjunction with in vitro fertilization, since genetic analysis is done on embryos obtained in the laboratory, before transfer. This means that the test is not a separate analysis, independent of IVF, but part of a larger assisted reproductive process.

2.Depending on the indication, the doctor may recommend:
PGT-M, for the risk of transmission of a monogenic disease,
PGT-SR, for structural chromosomal rearrangements,
PGT-A, for the evaluation of embryonic aneuploidies.
This classification is recognized in the ESHRE and ACOG recommendations.

3.The result of PGT should be interpreted carefully. ACOG shows that although PGT-M and PGT-SR can be useful in well-selected situations, an unaffected or euploid outcome does not guarantee the success of implantation nor does it completely rule out all possible causes of unfavorable course of pregnancy. For PGT-A, clinical utility can depend a lot on context, and the test also has methodological limits.

4.General recommendations for patients interested in PGT include:

conducting a specialist consultation before the start of the procedure,
genetic counseling when there is a known hereditary risk,
understanding the difference between embryonic selection and prenatal diagnosis,
correlation of the result with clinical and reproductive history,
continued monitoring of pregnancy even after a favorable outcome.

Pre-implantation screening or genetic testing may reduce the risk of transferring affected embryos for certain indications, but it does not replace standard prenatal care or prenatal testing when recommended later.

5. When do we ask ourselves the question of performing PGT?
When there is a genetic disease in the family, when one of the partners is a carrier of a mutation or chromosomal abnormality, when there is a recommendation for genetic evaluation within IVF or when the couple wants to better understand the options available to reduce a known genetic risk. The exact indication must be established individually, after specialist consultation and often after genetic counseling.

Schedule a consultation at the CMIB

At CMIB, we help you understand your preimplantation genetic testing options correctly and choose, together with your specialist doctor, the right approach for your case. Make an appointment for counseling and find out if PGT is recommended in your treatment plan.

‍