Understanding PGT-A: Genetic Testing Before Embryo Transfer

Understanding PGT-A: How Genetic Testing Improves IVF Outcomes

Preimplantation Genetic Testing for Aneuploidies, commonly known as PGT-A, is one of the most significant advances in modern IVF treatment. This sophisticated screening technique allows embryologists to examine embryos for chromosomal abnormalities before they are transferred to the uterus, dramatically improving the chances of a successful pregnancy and reducing the risk of miscarriage. For patients undergoing IVF treatment at GynoLife IVF Center in Cyprus, PGT-A represents a powerful tool for optimizing outcomes and providing greater peace of mind during the fertility journey.

In this comprehensive guide, we explain what PGT-A is, how it works, who should consider it, and how it fits into the broader IVF treatment process. Whether you are just beginning to explore IVF or are considering PGT-A as an addition to an upcoming cycle, this article will help you understand the benefits and limitations of this important technology.

What Is PGT-A?

PGT-A is a laboratory procedure that screens embryos for aneuploidy, which is the presence of an abnormal number of chromosomes. A normal human cell contains 46 chromosomes arranged in 23 pairs. An embryo with the correct number of chromosomes is called euploid, while an embryo with too many or too few chromosomes is called aneuploid. Aneuploid embryos are the most common cause of implantation failure, miscarriage, and certain genetic conditions such as Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13).

By identifying euploid embryos before transfer, PGT-A allows fertility specialists to select the embryo with the highest likelihood of implanting successfully and developing into a healthy pregnancy. This targeted approach represents a major improvement over traditional embryo selection methods, which rely primarily on visual assessment of embryo morphology under the microscope.

How Does PGT-A Work?

The PGT-A process involves several carefully coordinated steps that take place during a standard IVF cycle. Here is a detailed overview of how it works:

Step 1: IVF and Embryo Culture

PGT-A begins with a standard IVF cycle. The patient undergoes ovarian stimulation, egg retrieval, and fertilization (typically using ICSI to ensure the highest fertilization rates). The resulting embryos are then cultured in the laboratory for five to six days until they reach the blastocyst stage. The blastocyst is a more developed embryo consisting of approximately 100 to 200 cells, making it possible to safely remove a small sample for genetic analysis without harming the embryo’s development.

Step 2: Trophectoderm Biopsy

At the blastocyst stage, the embryologist performs a trophectoderm biopsy, which involves carefully removing a small number of cells (typically 5 to 10) from the outer layer of the embryo called the trophectoderm. This layer will eventually develop into the placenta, not the baby itself. The biopsy is performed using a highly precise laser and micromanipulation tools under the microscope. The procedure is well-established and, when performed by experienced embryologists, does not negatively affect the embryo’s ability to implant and develop normally.

Step 3: Genetic Analysis

The biopsied cells are sent to a specialized genetics laboratory for analysis. In 2026, the most common technology used for PGT-A is Next-Generation Sequencing (NGS), which provides a comprehensive and highly accurate assessment of all 23 pairs of chromosomes. NGS can detect whole-chromosome aneuploidies as well as segmental abnormalities (gains or losses of chromosome segments). Results are typically available within 7 to 14 days, depending on the laboratory.

Step 4: Embryo Vitrification

While waiting for PGT-A results, the biopsied embryos are vitrified (frozen) using ultra-rapid freezing technology. Modern vitrification techniques achieve survival rates exceeding 99%, meaning there is virtually no loss of embryo quality during the freezing process. Once the genetic results are available, euploid embryos are identified and prepared for a frozen embryo transfer (FET) in a subsequent cycle.

Step 5: Frozen Embryo Transfer

In the transfer cycle, the patient’s endometrium is prepared using hormone medications to create an optimal environment for implantation. The selected euploid embryo is thawed and transferred to the uterus in a simple, painless procedure. Because the embryo has already been screened for chromosomal normality, the chances of successful implantation are significantly higher compared to transferring an untested embryo.

Who Should Consider PGT-A?

While PGT-A can benefit a wide range of IVF patients, it is particularly recommended for certain groups:

Women Over 35

The incidence of chromosomal abnormalities in embryos increases significantly with maternal age. At age 30, approximately 30% of embryos are aneuploid. By age 38, this figure rises to about 60%, and by age 42, it can exceed 80%. PGT-A is especially valuable for older patients because it identifies which embryos are chromosomally normal, preventing the transfer of embryos that would likely result in failed implantation or miscarriage.

Patients with Recurrent Pregnancy Loss

Couples who have experienced two or more miscarriages may benefit from PGT-A, as chromosomal abnormalities are the most common cause of early pregnancy loss. By selecting euploid embryos, PGT-A can significantly reduce the risk of further miscarriages.

Patients with Previous Failed IVF Cycles

If you have undergone multiple IVF transfers without success, PGT-A can help determine whether chromosomal abnormalities in your embryos may be contributing to implantation failure. This information can guide your treatment team in adjusting your protocol and selecting the best possible embryo for your next transfer.

Patients with Known Chromosomal Issues

If either partner carries a balanced chromosomal translocation or other structural rearrangement, there is an increased risk of producing aneuploid embryos. PGT-A (and its related form, PGT-SR) can screen embryos to identify those with a normal or balanced chromosomal complement.

Patients Who Want to Reduce the Risk of Multiple Pregnancies

PGT-A supports the practice of elective single embryo transfer (eSET). When you know that the embryo being transferred is chromosomally normal, you can be confident in transferring just one embryo, significantly reducing the risk of twins or higher-order multiples while maintaining excellent success rates.

Benefits of PGT-A

The clinical evidence supporting PGT-A has grown substantially in recent years. Here are the primary benefits:

• Higher implantation rates: Euploid embryos have implantation rates of 60% to 70%, compared to 30% to 40% for untested embryos in the general IVF population.
• Reduced miscarriage risk: PGT-A can reduce the miscarriage rate to approximately 10% to 15%, compared to 20% to 30% without testing.
• Faster time to pregnancy: By selecting the best embryo from the start, PGT-A can reduce the number of transfer cycles needed to achieve a successful pregnancy.
• Lower risk of chromosomal conditions: PGT-A virtually eliminates the risk of conditions such as Down syndrome, Edwards syndrome, and Patau syndrome.
• Support for single embryo transfer: PGT-A enables confident single embryo transfer, reducing the health risks associated with multiple pregnancies.
• Emotional benefits: Knowing that the embryo transferred has been screened and found to be chromosomally normal can provide significant emotional reassurance during the two-week wait following transfer.

Limitations and Considerations

While PGT-A offers significant advantages, it is important to understand its limitations:

PGT-A Does Not Guarantee Pregnancy

Transferring a euploid embryo does not guarantee implantation or a live birth. Other factors, such as endometrial receptivity, immune factors, and embryo quality beyond chromosomal status, also play important roles. However, PGT-A significantly improves the odds compared to transferring an untested embryo.

Mosaicism

Mosaicism occurs when an embryo contains a mixture of chromosomally normal and abnormal cells. PGT-A may detect mosaic embryos, which present a clinical dilemma. Some mosaic embryos can self-correct and lead to healthy pregnancies, while others may not. Your fertility team will discuss the implications of mosaic results and help you make an informed decision about whether to transfer a mosaic embryo.

Not All Embryos Reach Blastocyst Stage

PGT-A requires embryos to be cultured to the blastocyst stage for biopsy, and not all embryos will reach this point. Patients with a low number of embryos may find that they have few or no embryos available for testing. This is an important consideration when planning your treatment.

Additional Cost

PGT-A adds to the overall cost of an IVF cycle. However, when considering the potential savings from avoiding unsuccessful transfers and the emotional toll of failed cycles or miscarriages, many patients and clinicians agree that the investment in PGT-A is worthwhile, particularly for patients in higher-risk categories.

PGT-A vs. Other Forms of Genetic Testing

It is helpful to understand how PGT-A compares to other forms of preimplantation genetic testing:

• PGT-A (Aneuploidy Screening): Screens for abnormal chromosome numbers across all 23 pairs. Recommended for general IVF patients, especially those over 35 or with recurrent loss.
• PGT-M (Monogenic/Single Gene Disorders): Tests for specific inherited genetic conditions such as cystic fibrosis, sickle cell disease, or BRCA mutations. Recommended when one or both parents are known carriers of a genetic disorder.
• PGT-SR (Structural Rearrangements): Screens for chromosomal structural abnormalities in patients who carry balanced translocations or inversions.

At GynoLife IVF Center, we offer all forms of preimplantation genetic testing and will recommend the most appropriate option based on your individual circumstances.

PGT-A at GynoLife IVF Center

Our laboratory is equipped with the latest technology for performing trophectoderm biopsies with the highest level of precision and care. We partner with leading accredited genetics laboratories that utilize Next-Generation Sequencing for accurate and reliable results. Our team of experienced embryologists and fertility specialists will guide you through every step of the process, from deciding whether PGT-A is right for you to interpreting your results and planning your embryo transfer.

Take the Next Step

If you are considering IVF treatment and want to learn more about how PGT-A can improve your chances of success, we invite you to speak with our team. Understanding your options is the first step toward making the best decisions for your family.

Book a free consultation with GynoLife IVF Center today and discover how preimplantation genetic testing can help you achieve a healthy pregnancy.