Fertulity IVF
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Preimplantation Genetic Testing (PGT):  Selection of Healthy Embryos before Implantation

What Is Genetic Embryo Testing (PGT)?

Preimplantation Genetic Testing (PGT) is a modern and specialized diagnostic method applied within the context of in vitro fertilization (IVF), with the aim of evaluating the genetic material of embryos before embryo transfer.

Through this process, it is possible to select embryos that do not carry specific genetic or chromosomal abnormalities, thereby enhancing the chances of successful implantation and a healthy pregnancy.

Unlike other forms of testing performed during pregnancy, Preimplantation Genetic Testing is carried out before the embryo implants in the uterus. This means that evaluation takes place at a very early stage, offering the possibility of making decisions based on scientific data before pregnancy begins.

At FertUlity, Preimplantation Genetic Testing is integrated into a fully personalized treatment plan, designed according to the medical history, needs, and goals of each couple or individual.

Stage 1: Ovarian stimulation and egg retrieval

The process begins with medication-based ovarian stimulation, with the aim of developing multiple follicles and producing more than one egg. This is particularly important within the context of PGT, as it increases the number of embryos that can be created and, consequently, the chances of identifying genetically healthy embryos.

Egg retrieval is performed under ultrasound guidance and light anesthesia, in a controlled and safe environment. The eggs are carefully collected and immediately transferred to the embryology laboratory, where their maturity is evaluated and they are prepared for fertilization.

Stage 2: Fertilization and embryo development

The mature eggs are fertilized in the laboratory, usually through the method of intracytoplasmic sperm injection (ICSI), during which a sperm cell is inserted directly into the egg. The choice of ICSI is particularly important within the context of PGT, as it reduces the risk of contamination of the genetic material and ensures greater accuracy in the subsequent analysis.

After fertilization, the embryos are cultured under specially designed laboratory conditions for approximately 5–6 days, until they reach the blastocyst stage. At this stage, the embryo has separated into two main cell masses: the inner cell mass, which will develop into the embryo, and the trophectoderm, which will form the placenta.

Stage 3: Embryo biopsy

The biopsy is performed at the blastocyst stage and is one of the most critical steps of the procedure. During the biopsy, a few cells are removed from the trophectoderm, meaning from the outer part of the embryo, without affecting the inner cell mass that will give rise to the embryo itself.

The procedure requires a high level of technical precision and experience, as the aim is to obtain sufficient genetic material without disturbing the viability of the embryo. When performed correctly, the biopsy is considered safe and does not affect implantation ability.

Stage 4: Genetic analysis

The biopsy is performed at the blastocyst stage and is one of the most critical steps of the procedure. During the biopsy, a few cells are removed from the trophectoderm, meaning from the outer part of the embryo, without affecting the inner cell mass that will give rise to the embryo itself.

The procedure requires a high level of technical precision and experience, as the aim is to obtain sufficient genetic material without disturbing the viability of the embryo. When performed correctly, the biopsy is considered safe and does not affect implantation ability.

Stage 5: Cryopreservation and embryo selection

After the biopsy, the embryos are cryopreserved (vitrification) until the genetic analysis is completed. Modern cryopreservation technology allows the quality and viability of embryos to be maintained at very high levels.

Once the results are available, the embryo or embryos that do not carry the genetic abnormalities being tested for are selected. Embryo transfer is performed at a later stage, in a suitably prepared endometrial environment, increasing the chances of successful implantation.

How is Preimplantation Genetic Testing (PGT) performed?

Preimplantation Genetic Testing is part of the in vitro fertilization process and follows specific, strictly defined stages. Accuracy and specialization at every step are of decisive importance for the reliability of the results.
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Types of Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT) is not a single test, but a set of specialized genetic analyses applied according to the history and needs of each couple. The differentiation between the types of PGT is based on the type of genetic or chromosomal abnormalities intended to be detected, as well as the reason for which the testing has been recommended.

The correct categorization and selection of the appropriate type is critical, as each form of PGT answers a different clinical question: from the evaluation of the chromosomal integrity of embryos to the targeted testing of specific hereditary diseases.
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PGT-A (Testing for Aneuploidies)

PGT-A concerns the detection of numerical chromosomal abnormalities, meaning conditions in which embryos have more or fewer chromosomes than normal. Humans normally have 46 chromosomes (23 pairs), and any deviation from this number is characterized as aneuploidy.

Aneuploidies are one of the most common causes of implantation failure, biochemical pregnancy, or miscarriage. In some cases, they may also lead to syndromes such as trisomy 21 (Down syndrome), trisomy 18, or trisomy 13.

PGT-A testing allows the selection of embryos with a normal number of chromosomes (euploid embryos), which have significantly increased chances of:
Implanting successfully
Developing into a viable pregnancy
Leading to the birth of a healthy child
The value of PGT-A is particularly important in women of advanced reproductive age, where the likelihood of aneuploidies increases significantly, as well as in cases of repeated failed attempts or recurrent miscarriages.

PGT-M (Testing for Monogenic Diseases)

PGT-M is a targeted form of genetic testing applied when there is a known history of a specific hereditary disease in the family or when the parents are carriers of a specific genetic mutation.

Unlike PGT-A, which examines the number of chromosomes, PGT-M focuses on specific genes. Through this process, it is possible to identify embryos that carry or do not carry the specific mutation.

Indicatively, PGT-M may be used to avoid hereditary transmission of diseases such as:
Mediterranean anemia (β-thalassemia)
Cystic fibrosis
Duchenne muscular dystrophy
Huntington’s disease
Other rare monogenic syndromes
The procedure requires a high level of personalization, as a special genetic protocol is designed for the specific couple before PGT-M is applied. This makes the testing highly accurate, but also demanding in terms of preparation.

At FertUlity, this approach is carried out in collaboration with specialized genetic laboratories, ensuring the maximum possible reliability of the results.

PGT-SR (Testing for Structural Chromosomal Abnormalities)

PGT-SR concerns the detection of structural chromosomal abnormalities, such as balanced translocations, inversions, or other rearrangements. These abnormalities may be present in one of the two parents without causing apparent problems for them, yet they can significantly affect reproductive capacity.

Specifically, carriers of such rearrangements have an increased risk of:
Creating embryos with unbalanced genetic material
Recurrent miscarriages
Failed implantations
Birth of a child with genetic abnormalities
PGT-SR allows the identification of embryos with the correct chromosomal structure, distinguishing them from those carrying imbalances. In this way, the likelihood of a successful and ongoing pregnancy is significantly increased.

The application of this specific test requires prior diagnosis of the chromosomal rearrangement in one parent, through karyotyping.

How is the appropriate type of PGT selected?

The selection of the appropriate type of Preimplantation Genetic Testing is not a generalized procedure, but is based on personalized medical evaluation. Factors such as the history of miscarriages, the results of previous IVF cycles, the woman’s age, as well as the presence of known genetic mutations, carriers of hereditary diseases, or chromosomal abnormalities, determine the appropriate type of PGT and the strategy that will be followed.

In many cases, a combined approach or specialized testing design may be required in order to fully cover the needs of the couple.

At FertUlity, the decision regarding the application and type of PGT is made after detailed counseling and diagnostic testing, with the aim of providing a fully targeted and scientifically documented solution.

Who are suitable candidates for PGT?

Preimplantation Genetic Testing is not necessary for every case of in vitro fertilization, but is intended for specific groups of patients where its application may offer substantial clinical benefit. The correct selection of candidates is based on a combination of factors related to the medical history, reproductive course, and genetic characteristics of the couple.

One of the main categories is women of advanced reproductive age, as over time the probability of creating embryos with chromosomal abnormalities increases significantly. In these cases, PGT-A may contribute to the selection of embryos with a normal karyotype, improving the chances of success.

Equally important is the indication for couples with a history of recurrent miscarriages, where the cause is often related to genetic abnormalities of the embryos. At the same time, PGT is recommended in cases of repeated failed in vitro fertilization cycles, when there is suspicion that implantation failure is due to the genetic integrity of the embryos.

It is also particularly important for couples with a known family history of genetic diseases or for individuals who are carriers of specific gene mutations, as through PGT-M it becomes possible to avoid transmission of the disease to the next generation. Correspondingly, in cases where one of the two partners is a carrier of chromosomal rearrangements, such as balanced translocations, PGT-SR contributes to the selection of embryos with the correct chromosomal structure.

Overall, Preimplantation Genetic Testing is mainly indicated in cases such as:
Women over 38–40 years old
Recurrent miscarriages
Repeated failed IVF attempts
Known family history of genetic diseases
Carriers of monogenic mutations
Carriers of chromosomal abnormalities or rearrangements
Need for more targeted embryo selection before embryo transfer
At FertUlity, the indication for PGT is not based on general rules, but on detailed and personalized evaluation. Through a combination of medical experience and modern diagnostic tools, the appropriate strategy is designed for each patient, with the aim of maximizing the chances of success and achieving a healthy pregnancy.

What are the benefits of Preimplantation Genetic Testing?

Preimplantation Genetic Testing (PGT) is one of the most advanced tools in modern in vitro fertilization, as it focuses not only on achieving pregnancy, but also on its quality and safety. Through the genetic evaluation of embryos before implantation, it becomes possible to select those with the best conditions for normal development.

One of the most important benefits of PGT is the increased likelihood of successful implantation. When embryos with a normal chromosomal profile are selected, the likelihood of cycle failure is significantly reduced, as the transfer of embryos without the potential to develop is avoided. At the same time, PGT contributes to reducing the risk of miscarriage, particularly in cases where it is associated with chromosomal abnormalities. This is particularly important for couples who have experienced recurrent miscarriages, as the test can identify and exclude embryos with genetic abnormalities.

In addition, in cases of known family history, Preimplantation Genetic Testing offers the possibility of avoiding the transmission of serious hereditary diseases. Through PGT-M, embryos that do not carry specific pathogenic mutations can be selected, allowing couples to proceed with greater safety.

Another important advantage is the optimization of the overall time required to achieve pregnancy. With the correct selection of embryos from the beginning, the need for multiple IVF cycles is reduced, which has both medical and psychological benefits for patients.

At FertUlity, Preimplantation Genetic Testing is integrated into a comprehensive strategy that aims not only at the success of the treatment, but also at creating the best possible conditions for a healthy and smooth progression of pregnancy.
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Frequently Asked Questions About Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing (PGT)

Preimplantation Genetic Testing can detect both chromosomal and specific genetic abnormalities, depending on the type of testing applied. Through PGT-A, aneuploidies are identified, meaning abnormalities in the number of chromosomes, which are a frequent cause of miscarriages and failed implantations. With PGT-M, it is possible to detect monogenic diseases, such as Mediterranean anemia or cystic fibrosis, while PGT-SR concerns the detection of structural chromosomal abnormalities, such as translocations. It is important to emphasize that the testing is targeted and does not cover all possible genetic conditions.

Are there any limitations or disadvantages?

Although PGT is a particularly powerful diagnostic tool, it is not a panacea. It cannot detect all genetic abnormalities, while in some cases the results may be complex, as occurs with mosaicism. In addition, the procedure requires high specialization and may increase the overall cost of treatment. For this reason, PGT should be applied after proper medical guidance and personalized evaluation.

When is PGT performed?

Preimplantation Genetic Testing is performed within the context of an in vitro fertilization cycle and specifically before embryo transfer. Embryo biopsy is performed at the blastocyst stage, a few days after fertilization, and is followed by genetic analysis. The embryos are cryopreserved until the results are completed, and then the appropriate embryo is selected for transfer.

What is the cost of Preimplantation Genetic Testing?

The cost of PGT depends on various factors, such as the type of testing (PGT-A, PGT-M, or PGT-SR), the number of embryos to be tested, and the specific features of each case. It is a specialized laboratory procedure that requires advanced technology and collaboration with specialized genetics laboratories. At FertUlity, full information and transparency are provided, so that each couple knows in advance the options and the overall plan.

Is the PGT procedure safe for the embryo?

Embryo biopsy is performed at the blastocyst stage and involves taking a few cells from the trophectoderm, which does not develop into the embryo itself but into the placenta. When the procedure is carried out by specialized embryologists and with modern techniques, it is considered safe and does not affect the viability or implantation ability of the embryo.

Does PGT guarantee pregnancy success?

Preimplantation Genetic Testing significantly increases the chances of successful implantation and reduces the risk of miscarriage; however, it cannot guarantee pregnancy 100%. Success also depends on other factors, such as the quality of the endometrium, the woman’s general health, and the overall reproductive profile.

Can PGT reduce the number of IVF attempts?

Yes, in many cases PGT contributes to reducing the number of IVF cycles required to achieve pregnancy. By selecting genetically suitable embryos from the beginning, unnecessary embryo transfers are avoided and the efficiency of each treatment cycle is increased. This has both medical and psychological benefits for the couple.

How long do PGT results take?

PGT results are usually issued within 2–3 weeks from the embryo biopsy. During this period, the embryos are safely cryopreserved. Once the results are received, embryo transfer is scheduled with a selected genetically healthy embryo, maximizing the likelihood of implantation and successful pregnancy.

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In an era where fertility requires knowledge, care, and substantial guidance, FertUlity is not an impersonal clinic. It is two people who look you in the eye and accompany you step by step on the journey you dream of.

Dr. Chrysostomos (Makis) Papadopoulos Obstetrician – Gynecologist, MD, PhDc, MIC I

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Dr. Maria Oikonomou Obstetrician – Gynecologist

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