Preimplantation Genetic Testing

Preimplantation genetic testing (PGT) is a series of diagnostic tests performed on embryos created through IVF (in vitro fertilization). Its main goal is to assess whether these embryos are suitable for transfer to the uterus.

Thanks to PGT, it is possible to select only those embryos that have the greatest potential for healthy development, minimizing the risk of genetic disorders or other complications. This method thus increases the success rate of IVF and improves the overall outcomes of infertility treatment.

Preimplantation genetic testing can be considered for any of the following issues:

• Recurrent miscarriage in the first trimester.
• Repeated IVF failure.
• Advanced maternal age (e.g., to test for Down syndrome if the mother is over 38 years old).
• One or both partners are carriers of single gene mutations, to avoid its transmission to their children.
• Either partner has a chromosome rearrangement (e.g. translocation) that can result in chromosomal variations in the eggs or sperm, potentially leading to miscarriage or health problems in the child.
• A previous pregnancy has been affected by a chromosomal variation.
• In the case of teratospermia or severe oligospermia and the ICSI method is being used.
• If one or both partners have undergone cancer treatment (such as chemotherapy or radiotherapy) in the past year.

This testing helps in identifying and selecting embryos free from specific genetic disorders, enhancing the chances of a healthy pregnancy.

For PGT testing, it is necessary to remove 5-10 cells from the embryo. This process is called a biopsy and is always performed by an experienced embryologist. The removed cells are then tested, and the embryo is frozen until the results are available. This usually takes 2-4 weeks.

PGT-A: Preimplantation Genetic Testing of Aneuploidy

PGT-A, or preimplantation genetic testing for aneuploidy, is a method used to check embryos for chromosomal abnormalities before they are transferred into the uterus.

Chromosomes are tiny structures inside our cells that hold our genes, which contain all the instructions needed for our development. Each of us has 23 pairs of chromosomes.

Sometimes, during reproduction, embryos can end up with too many or too few chromosomes. This is called aneuploidy.

PGT-A helps to identify these common chromosomal issues in embryos. This test can be especially helpful for couples facing infertility, particularly if the woman is older, has had several unsuccessful IVF attempts, or has experienced multiple miscarriages.

The primary aim of PGT-A is to ensure that only embryos with the correct number of chromosomes are transferred to the uterus, increasing the chances of a successful pregnancy and reducing the risk of early miscarriage. This way, it helps in achieving a healthy pregnancy and a healthy baby.

PGT-M: Preimplantation Genetic Testing for Monogenic / Single Gene Defects and PGT-SR: Preimplantation Genetic Testing for Structural Rearrangements

PGT-M (preimplantation genetic testing for monogenic disorders) and PGT-SR (preimplantation genetic testing for structural rearrangements) are important options for couples when either partner has a known serious genetic disease or is at risk of having a baby with such a condition or chromosomal changes.
The main goal of PGT-M and PGT-SR is to diagnose genetic conditions before transferring the embryo, thus reducing the risk of the baby having a serious genetic disease or chromosomal abnormalities.

We recommend considering PGT-M/PGT-SR if:

• The partner is a carrier of or has a serious genetic disease or chromosomal changes.
• A previous abortion was undertaken due to serious genetic disease or chromosomal changes in the fetus.
• A child was born with a serious genetic disease or chromosomal changes.

By using PGT-M and PGT-SR, we aim to help our patients to achieve a healthy pregnancy and a healthy baby, providing peace of mind and reducing the risk of passing on serious genetic conditions.

Preimplantation genetic testing (PGT) is a process used in conjunction with in vitro fertilization (IVF) to test embryos for genetic and chromosomal abnormalities before they are transferred to the uterus. Here is an overview of what PGT involves:

IVF and Embryo Development:

• Eggs are retrieved from the ovaries and fertilized with sperm in the laboratory to create embryos.
• The embryos are cultured for several days until they reach the blastocyst stage (typically days 5 or 6).

Embryo Biopsy:

• A few cells are carefully removed from each embryo. This procedure is minimally invasive and is usually done at the blastocyst stage to minimize any potential impact on the embryo.

Genetic Analysis:

• The biopsied cells are analyzed in a laboratory to check for genetic and chromosomal abnormalities.
• Different types of PGT include:

1. PGT-A (Aneuploidy): Checks for abnormal numbers of chromosomes.
2. PGT-M (Monogenic): Tests for specific genetic disorders known to be present in the parents.
3. PGT-SR (Structural Rearrangements): Detects structural changes in chromosomes.

Embryo Selection:

• Based on the genetic analysis, embryos without detected abnormalities are selected for transfer.
• The selected embryos are those with the correct number of chromosomes or without the specific genetic disorder being tested.

Embryo Transfer:

• One or two selected embryos are transferred to the uterus with the aim of achieving a successful pregnancy.

Cryopreservation:

• Additional embryos that are genetically normal can be frozen (cryopreserved) for future use.

PGT helps increase the chances of a successful pregnancy and reduces the risk of miscarriage and genetic disorders by ensuring that only healthy embryos are transferred. 

PGT-A eliminates embryos with chromosomal defects, significantly shortening our patients‘ path to their future child. Embryo transfers of embryos with defects tend to be unsuccessful, or result in spontaneous miscarriages. These events can prolong the journey to parenthood by several months, especially when a uterine cavity revision is necessary.

How Does PGT-A Increase Treatment Success?

• Reduction in the Number of Unsuccessful Embryo Transfers and Associated Psychological Burden: PGT-A helps identify and select embryos without chromosomal defects, reducing the likelihood of transferring embryos that would not result in a successful pregnancy. It also significantly lowers the emotional toll from unsuccessful pregnancies.
• Reduction in the Number of Spontaneous Miscarriages: By screening for chromosomal abnormalities, PGT-A lowers the risk of miscarriage due to aneuploidy, leading to a more stable and successful pregnancy outcome.
• Lower Risk of Pregnancy with a Fetus Carrying a Chromosomal Defect: PGT-A ensures that only embryos with the correct number of chromosomes are transferred, thereby minimizing the risk of chromosomal abnormalities in the fetus.
• Providing Valuable Information to Patients: The insights gained from PGT-A can guide patients in making informed decisions about further treatment options, such as using donated eggs, sperm, or embryos, if necessary.