What Is PGT testing? Facts about IVF embryonic genetic testing

December 17, 2024

Preimplantation genetic testing (PGT) is a procedure used to screen embryos for genetic conditions or chromosomal abnormalities during an in vitro fertilization (IVF) cycle. The goal is to increase the chance that an embryo selected for transfer to the uterus has the genetic building blocks in place to potentially result in a healthy live birth.

Although PGT is not a predictor of IVF success, and does not guarantee the absence of all genetic risks, it is an important part of the IVF process. PGT can help patients and their care providers reduce the probability of implantation failure, miscarriage, and congenital disorders associated with genetic mutations. Read on to learn more about this piece of the IVF process.

What Is PGT Testing?

Preimplantation genetic testing (PGT) is a broad term that refers to all of the embryonic genetic testing conducted during IVF, before a viable embryo is selected and transferred to the uterus. There are three different types of PGT that look at either the genes or chromosomes of an embryo, and evaluate them for different things.

The different types of PGT

• PGT-A (Aneuploidy testing). Aneuploidy is a genetic disorder that results in a cell with either an extra or missing chromosome. PGT-A is the most common form of PGT performed, and looks at the number of chromosomes present in an embryo to ensure it is not an aneuploid. Most people have 46 chromosomes, so embryos with more or less than that are identified through PGT-A and not considered for transfer.
• PGT-M (Monogenic or single gene testing). Monogenic disorders are genetic conditions associated with a single gene. PGT-M is focused on specific genes that one (or both) parents carry. An embryo carrying that gene could indicate a future child affected by a genetic disorder such as cystic fibrosis or sickle cell anemia. PGT-M allows for the selection of embryos that are free from specific genetic conditions.
• PGT-SR (Structural rearrangements). Structural rearrangements within a chromosome, such as inversion or translocation, are a concern when they exist in a parent because they are more at risk for producing embryos with chromosomal abnormalities. PGT-SR is an additional chromosomal screening available in these situations to ensure the embryos selected for transfer do not have genetic material that has been deleted, duplicated, inverted, or translocated to the wrong place.

Why is embryonic genetic testing important?

Embryonic genetic testing is important for many reasons, all rooted in its primary purpose: to increase the success rate of IVF. The ability to gain as much insight as possible about the health of an embryo empowers fertility providers and patients to make informed reproductive decisions and improve outcomes for both parents and children. Embryo evaluation and selection is greatly improved with additional chromosomal and genetic data behind it.

Testing embryos for chromosomal abnormalities with PGT-A or PGT-SR can increase the likelihood of a successful pregnancy. Embryos with a normal chromosomal makeup are more likely to implant in the uterus, reducing the risk of miscarriage and improving the chances of a live birth. Testing embryos for specific genetic conditions with PGT-M can reduce the risk of parents passing on hereditary disorders, which positively impacts their peace of mind and the health of their future children.

The process of PGT testing

PGT is an additional procedure that can be added into a typical IVF cycle. Some people may opt for only one type of PGT, or undergo all three types depending on the recommendation from their care provider. In all cases, there are four primary steps to the PGT process.

1. IVF cycle & embryo creation

Embryos are created using normal IVF methods. Eggs are collected and fertilized with sperm, then cultured in a controlled laboratory environment.

2. Embryo biopsy

A small sample of cells are collected from the outer layer of the embryo, the part that will eventually become the placenta. This biopsy is taken from a blastocyst, i.e. a day 5 or day 6 embryo.

3. Genetic testing of embryo cells

The embryonic cell samples are screened for the genetic conditions or chromosomal abnormalities that PGT-A, PGT-M, or PGT-SR are focused on identifying.

4. Results and embryo selection

Once the testing is complete, a report is shared from the laboratory to the fertility care provider to help determine how many embryos are appropriate to transfer and which ones are most likely to result in a viable pregnancy.

IVF genetic testing success rates

When compared to traditional IVF without genetic testing, PGT can improve the chances of a successful live birth and reduce the rate of miscarriage by selecting chromosomally-normal embryos. This is especially true for patients of advanced maternal age, or patients with a history of pregnancy loss.

In a study of patients who chose not to include PGT-A in their IVF cycle compared to those who did include PGT-A, researchers found a statistically significant increase in pregnancy rate. The difference in groups was most notable as patient age increased.

• Under 35 years old
  50.4% (without PGT-A) vs 60.4% (with PGT-A)
• 35-37 years old
  47.5% (without PGT-A) vs 61.0% (with PGT-A)
• 38-40 years old
  37.7% (without PGT-A) vs 62.3% (with PGT-A)
• Over 40 years old
  26.2% (without PGT-A) vs 55.6% (with PGT-A)

Another study looked specifically at IVF patients with a history of two or more miscarriages. Not only were pregnancy rates higher when using PGT-A, but most importantly, PGT-A reduced the risk of pregnancy loss from 32% to 15%.

Yes, PGT is a valuable tool in selecting the best embryos for implantation and improving the success of IVF. However, it is not a guarantee of a successful pregnancy. There are many other factors involved when assessing the overall outcome of an IVF cycle, and it’s important to approach the process with realistic expectations.

Embryonic genetic testing costs

For many people, an important consideration when deciding whether or not to include PGT in an IVF cycle is the cost. The direct cost of PGT testing itself can range from $3000 to $14000, and typically includes the price of the embryo biopsy and genetic testing. There are also indirect costs to keep in mind, such as the cost of the IVF cycle as a whole, embryo freezing and storage fees (required for genetic testing and transfer), and even shipping fees for the laboratory conducting the testing.

The exact cost of PGT depends on a number of factors including:

• Type of PGT needed. PGT-A is the most common form of PGT, and tends to cost less than PGT-M or PGT-SR which require more complex testing procedures.
• Number of embryos tested. Although testing more embryos adds to the total cost, sometimes the cost per embryo can go down if multiple embryos are tested at once.
• Location of IVF treatment. As a general guideline, the higher the cost of living is in the area of your fertility clinic, the more expensive PGT will be.
• Clinic reputation and technology. Some clinics may simply be more expensive due to their reputation, demonstrated expertise, state-of-the-art facilities, or advanced techniques.
• Insurance and fertility benefits. Some insurance plans or employer-sponsored fertility benefits like Carrot may cover a portion of the costs of IVF and genetic testing, however coverage varies widely by provider, location, and specific plans.

While the upfront costs of PGT may seem high, many patients find that the financial investment is worth it when weighed against the potential long-term benefits. A key advantage of PGT is that it reduces the risk of genetic disorders and chromosomal abnormalities. This increases the chances of a successful pregnancy and a healthy child, and can help patients avoid the expense of multiple rounds of IVF in the long run.

Who should consider PGT testing?

The decision to include PGT in an IVF cycle should be made in conversation with your fertility care provider. They will have the best recommendation based on today’s fertility science and the specific factors involved in your journey to conceive. Typically, PGT is recommended for IVF patients that meet one of the following criteria:

• One or both parents have a history of genetic disorders in themselves or in their family background.
• Parents who have experienced previously failed embryo implantation, or two or more miscarriages.
• Parents with advanced maternal age (usually 35 or older).
• Parents experiencing unexplained infertility, numerous unsuccessful fertility treatments, or other non-genetic fertility challenges.

Pros and cons of embryonic genetic testing

There’s a lot to consider when it comes to PGT testing, and each person will weigh these benefits and concerns differently. Here are some of the potential pros and cons of these tests.

Pros

• Higher success rates for IVF cycles. An IVF cycle is a massive investment in time, money, and energy, so for many people PGT is an obvious choice to improve the chances of a successful pregnancy and avoid additional cycles.
• Reduced risk of miscarriages and genetic disorders. Genetically testing embryos before they are transferred to the uterus ensures the embryos are free of chromosomal abnormalities that commonly contribute to miscarriage, especially in early pregnancy.
• Improved decision-making in embryo selection. The embryo grading completed in a typical IVF cycle uses a microscope to examine visual factors such as cell number, structure, and fragmentation. Genetic testing evaluates embryos at the DNA level, and provides a more comprehensive picture of an embryo’s viability than visual cues alone.
• Avoids hereditary genetic conditions. There are over 1,700 inherited genetic conditions in which the exact gene mutation can be identified through PGT-M. Couples who carry genetic conditions can avoid passing them to their children thanks to embryonic testing.

Cons

• Additional cost on top of IVF expenses. PGT is an optional procedure that can be added to IVF, which means it adds additional costs and is not always covered by insurance.
• Ethical and moral concerns. The advancement of the embryo selection process could eventually lead to people being able to select for specific traits. The potential for this raises ethical and moral concerns about selective reproduction and puts PGT in the same conversation as eugenics.
• Potential for false positives or negatives, though rare. No genetic tests are 100% accurate, so there is always the possibility for an embryo to be either rejected unnecessarily or transferred with a genetic abnormality.
• Not all genetic conditions can be detected. At its core, PGT is confirming the absence of a genetic mutation in an embryo selected for transfer. However, not all congenital disorders are related to an identifiable gene or chromosome.
• Biopsy, freezing, and thawing risks. As embryos go through the biopsy and cryogenic processes required for PGT, there is a small risk of physical damage to the cells that could result in an implantation failure.

PGT testing: The choice is yours

For people who are undergoing IVF, PGT can be a valuable add-on that increases the probability of a successful cycle and healthy pregnancy. If you’re considering PGT, be sure to consult with your fertility specialist to explore if PGT is right for you and your unique fertility situation.