Preimplantation Genetic Testing (PGT)
A preventive step before embryo transfer
What is preimplantation genetic testing (PGT)
Preimplantation Genetic Testing (PGT) is an advanced laboratory technique performed during in vitro fertilization (IVF) cycles. Its goal is to analyze the genetic material of embryos before they are transferred into the uterus. In this way, only embryos without genetic abnormalities or chromosomal imbalances are selected for transfer, increasing the likelihood of a successful pregnancy and reducing the risk of miscarriage.
PGT combines reproductive medicine with molecular genetics and offers new possibilities for couples with increased genetic or reproductive risk.
When PGT is recommended
Woman’s age over 35
The risk of chromosomal abnormalities in the eggs increases, mainly trisomies such as Down syndrome.
Repeated miscarriages or failed IVF attempts
PGT can identify embryo-related issues that may be causing the losses.
Family history of genetic disease
When both partners are carriers of inherited disorders such as thalassemia or cystic fibrosis.
Male factor infertility with increased DNA fragmentation
Careful embryo selection reduces the risk of poor development or implantation failure.
How PGT is performed
The procedure requires specialized laboratory equipment and close collaboration between geneticists and embryologists, always within an IVF cycle. Embryos are cultured up to the blastocyst stage (5–6 days), after which a biopsy is performed to remove a few cells from the outer layer of each embryo with precision. These cells undergo genetic analysis using techniques such as PCR, FISH, or NGS.
Embryos are cryopreserved until results are available and the healthy ones are selected for transfer.
Types of PGT
PGT-A (Aneuploidy)
Detects numerical chromosomal abnormalities such as trisomies or monosomies.
PGT-M (Monogenic disorders)
For couples carrying specific single-gene conditions like thalassemia or muscular dystrophy.
PGT-SR (Structural rearrangements)
Used when one of the partners has balanced or unbalanced chromosomal rearrangements.
Combined testing
Applied in specific cases depending on medical history and previous findings.
Benefits and limitations of the method
PGT is a powerful tool for embryo selection and prevention, though it does not eliminate all risks. Transferring chromosomally normal embryos increases IVF success rates. It also reduces the likelihood of miscarriages or failed implantations due to genetic abnormalities and enables the prevention of inherited diseases.
However, PGT is not necessary for all IVF cases and should be applied only with proper medical justification.
Emotional and ethical considerations
Deciding to proceed with PGT requires thorough information, emotional readiness, and an understanding of the medical and ethical implications. Couples often feel reassured, knowing they are doing everything possible for their child’s health. It is also important to understand that genetic screening cannot detect all potential issues and does not guarantee a perfect outcome.
Embryo selection must be based on scientific and ethical criteria, and supported by a multidisciplinary team that provides expert care with empathy and respect.
Preimplantation Genetic Testing (PGT) is a significant advancement in reproductive medicine, offering safety, prevention, and informed decision-making to the couples who need it. When applied with proper indication and expertise, it can enhance the effectiveness of IVF and bring couples one step closer to their goal of healthy parenthood.