PGT Testing

PGT Testing: What It Is, How It Works, and Why It Matters

PGT testing stands for preimplantation genetic testing, a lab-based genetic screening process used during IVF (in vitro fertilization) to evaluate embryos before transfer. It helps identify certain chromosome abnormalities or specific inherited genetic conditions, depending on the type of PGT being performed. For people trying to build a family, including men being evaluated for fertility challenges, PGT testing can play an important role in embryo selection, miscarriage risk reduction in some cases, and decision-making around inherited disease.

At a glance: PGT testing does not improve sperm or egg quality, and it does not guarantee pregnancy or a healthy baby. What it can do is provide more information about embryos created during IVF, which may help a fertility specialist choose which embryo to transfer or whether additional counseling is needed.

Quick Takeaways

PGT testing is performed on embryos created through IVF before embryo transfer.
PGT-A looks for the correct number of chromosomes, PGT-M looks for a specific inherited condition, and PGT-SR looks for certain structural chromosome rearrangements.
PGT can sometimes improve embryo selection, but it does not guarantee implantation, pregnancy, or live birth.
For men, PGT may be relevant if there is a family history of a genetic disorder, known male-factor infertility, recurrent pregnancy loss, or a chromosomal rearrangement.
An embryo labeled euploid generally has the expected number of chromosomes; aneuploid means an abnormal chromosome number; mosaic means a mixed result.
PGT is a screening or targeted testing tool, not a complete health guarantee for an embryo.
Even after PGT, doctors often still recommend prenatal testing during pregnancy.
Genetic counseling is often useful before deciding whether PGT is right for you.

What Is PGT Testing?

PGT testing is a method of analyzing a small number of cells taken from an embryo, usually at the blastocyst stage, to look for specific genetic or chromosomal findings before the embryo is transferred to the uterus. The goal is to gather information that may help guide embryo selection during IVF.

In plain English, PGT asks: Does this embryo appear to have the usual chromosome makeup, or does it carry a known inherited condition we are specifically looking for?

The term “PGT testing” is often used broadly, but there are actually several different forms of preimplantation genetic testing. Each one answers a different question.

Types of PGT: PGT-A, PGT-M, and PGT-SR

The three main categories of preimplantation genetic testing are outlined below.

Type	Full Name	What It Looks For	Common Use Case
PGT-A	Preimplantation Genetic Testing for Aneuploidy	Abnormal number of chromosomes	Embryo selection in IVF, especially in some cases of advanced maternal age, recurrent implantation failure, or recurrent miscarriage
PGT-M	Preimplantation Genetic Testing for Monogenic/Single-Gene Disorders	A specific inherited genetic mutation	When one or both parents carry a known disease-causing variant, such as cystic fibrosis or sickle cell disease
PGT-SR	Preimplantation Genetic Testing for Structural Rearrangements	Chromosomal translocations or inversions	When a parent has a balanced translocation or another structural chromosome issue

PGT-A

PGT-A evaluates whether an embryo appears to have the expected number of chromosomes. Human cells usually contain 46 chromosomes, arranged in 23 pairs. If an embryo has an extra or missing chromosome, that is called aneuploidy. Many aneuploid embryos do not implant, miscarry early, or may lead to certain chromosomal conditions.

PGT-M

PGT-M is used when there is a known risk of passing on a single-gene disorder. This might include conditions inherited from the father, the mother, or both. If a male partner is known to carry a specific pathogenic variant, PGT-M may help identify embryos that are unaffected or not expected to develop that condition, depending on the inheritance pattern.

PGT-SR

PGT-SR is designed for people with certain structural chromosome rearrangements, such as balanced translocations. A person can be healthy and still carry a chromosomal rearrangement that raises the risk of creating embryos with unbalanced chromosome material, which may contribute to infertility, failed IVF cycles, or recurrent miscarriage.

Why PGT Testing Matters in Fertility Care

PGT testing matters because embryo genetics can affect whether an embryo implants, whether a pregnancy continues, and whether there is a risk of a known inherited disease. That said, PGT is a tool for better information, not perfect prediction.

Potential reasons PGT may be discussed include:

Recurrent pregnancy loss
Repeated failed IVF embryo transfers
Advanced maternal age, which is associated with higher rates of aneuploid embryos
A known family history of a genetic disorder
One partner carrying a single-gene mutation
One partner having a balanced translocation or other chromosomal rearrangement
A desire to reduce the risk of transferring an embryo affected by a specific inherited disorder

For some couples, PGT can reduce uncertainty. For others, it may add cost, complexity, and emotional weight without clearly improving outcomes. The value of PGT depends on the clinical situation.

What PGT Testing Means in Men’s Fertility

Although PGT is often discussed in the context of embryo and egg quality, it can be highly relevant in male fertility too. Men may encounter PGT testing during a fertility workup or IVF planning if there are concerns related to genetics, sperm quality, or family history.

When PGT may be relevant for men

Known genetic mutation: A man carries a pathogenic variant linked to an inherited condition.
Chromosomal rearrangement: Karyotype testing shows a balanced translocation or inversion.
Severe male factor infertility: In some cases, male infertility is associated with genetic findings, such as Y chromosome microdeletions or karyotype abnormalities.
History of recurrent miscarriage: If repeated miscarriages occur, genetic testing of both partners may be recommended.
Prior child or pregnancy affected by a genetic condition: This may lead to targeted testing in future IVF cycles.

Important point for men

PGT does not treat male infertility itself. It does not improve sperm count, sperm motility, morphology, DNA fragmentation, or testosterone levels. Instead, it may help clarify whether embryos made from a man’s sperm are free of a known inherited issue or appear chromosomally normal, depending on the testing type.

Genetic issues in men that may intersect with IVF and PGT

Balanced chromosomal translocations
Y chromosome microdeletions
Klinefelter syndrome and other sex chromosome differences
CFTR gene variants associated with congenital bilateral absence of the vas deferens (CBAVD)
Inherited disorders passed in autosomal dominant, autosomal recessive, or X-linked patterns

If a genetic cause of male infertility is suspected, a fertility specialist may recommend karyotype analysis, carrier screening, or consultation with a genetic counselor before IVF and PGT decisions are made.

How the PGT Testing Process Works

PGT testing happens as part of an IVF cycle. While protocols vary by clinic, the basic process generally looks like this:

Ovarian stimulation and egg retrieval: Eggs are collected from the ovaries.
Fertilization: Eggs are fertilized with sperm, often using ICSI (intracytoplasmic sperm injection) in cases where genetic testing is planned.
Embryo development: Embryos grow in the lab for several days, usually to day 5, 6, or 7 blastocyst stage.
Embryo biopsy: A small number of cells are removed from the outer layer of the embryo, called the trophectoderm, which later becomes part of the placenta.
Freezing: The embryos are typically frozen while the genetic testing is performed.
Genetic analysis: The biopsied cells are sent to a specialized lab for PGT-A, PGT-M, PGT-SR, or a combination if appropriate.
Results review: The fertility team reviews which embryos are suitable for transfer consideration based on test findings and embryo quality.
Embryo transfer: A selected embryo is thawed and transferred in a later frozen embryo transfer cycle.

How long do PGT results take?

Turnaround time varies by clinic and lab. Results often take several days to a couple of weeks, especially if a custom probe or family-specific setup is needed for PGT-M.

Who May Consider PGT Testing?

PGT is not automatically right for every IVF patient. Whether it makes sense depends on age, diagnosis, family history, prior pregnancy outcomes, and personal preferences.

PGT may be considered in situations such as:

Known carrier status for a serious inherited condition
One partner with a balanced translocation or other structural chromosomal rearrangement
Recurrent pregnancy loss
Multiple failed IVF transfers
Advanced maternal age
Need to avoid passing on a specific known disorder
Use of IVF where embryo selection information may help guide transfer planning

PGT may be less helpful or more debatable when:

Very few embryos are expected
The goal is broad reassurance rather than testing for a defined risk
The patient assumes PGT can replace prenatal testing later in pregnancy
The couple has not had genetic counseling and may not fully understand the limitations

This is one reason individualized counseling matters. The same test can be high-value in one scenario and low-yield in another.

What’s Normal vs What’s Not?

PGT results are not reported the same way as a blood test with a normal reference range. Instead, embryos are usually described using terms such as euploid, aneuploid, or mosaic.

Result Term	What It Generally Means	What It May Mean for Transfer Planning
Euploid	Embryo appears to have the expected number of chromosomes	Often considered for transfer if otherwise suitable
Aneuploid	Embryo appears to have an abnormal number of chromosomes	Usually not selected for transfer
Mosaic	Embryo shows a mixture of normal and abnormal cell lines	Interpretation is complex; some mosaic embryos can result in healthy live births, but decision-making requires expert counseling
No result / inconclusive	Testing did not yield a clear answer	May require discussion of retesting, transfer decisions, or not using that embryo

What does “normal” mean in PGT-A?

In everyday conversation, a “normal” PGT-A result usually means the embryo tested euploid. That said, euploid does not mean the embryo is guaranteed to implant or that there is zero risk of miscarriage or medical problems. It means that, based on the cells tested, the embryo appears to have the expected chromosome count.

What does an abnormal result mean?

An abnormal result may mean the embryo likely has too many or too few chromosomes, carries the targeted mutation being tested for, or has an unbalanced structural rearrangement. The exact meaning depends on the type of PGT performed.

Accuracy, Limitations, and Risks of PGT Testing

PGT testing can be highly informative, but it is not perfect. Understanding the limitations is essential.

Key limitations

Sampling limits: Only a small number of cells are tested, and those cells may not perfectly represent the entire embryo.
Mosaicism: Some embryos contain a mix of normal and abnormal cells, making interpretation more difficult.
Not a full genetic screen: PGT-A does not check for every disease, developmental disorder, or birth defect.
False positives or false negatives can occur: While uncommon, no genetic test is flawless.
Embryo biopsy and freezing add complexity: Modern techniques are generally considered safe in experienced labs, but these steps are still part of an invasive IVF process.
Success still depends on many factors: Uterine health, embryo quality beyond chromosomal status, maternal factors, lab quality, and timing all matter.

Does PGT harm embryos?

Embryo biopsy is widely used in modern IVF, and many clinics consider it acceptably safe when done by experienced embryologists. Still, no procedure is entirely risk-free. The effect of biopsy may depend on embryo quality, lab skill, and the specific clinical context.

Can PGT miss a problem?

Yes. PGT can miss some problems because it only tests for what it is designed to analyze. For example:

PGT-A does not diagnose all genetic diseases.
PGT-M usually targets a specific mutation or condition, not every possible disorder.
Biopsied cells may differ from other cells in the embryo.

This is why prenatal testing during pregnancy is still commonly recommended.

Benefits and Drawbacks of PGT Testing

Potential Benefits	Potential Drawbacks
May help identify embryos unaffected by a known inherited condition	Adds cost to IVF
May improve embryo selection in some clinical situations	Does not guarantee pregnancy or live birth
May reduce transfer of embryos with clear chromosomal abnormalities	May reduce the number of embryos considered transferable
May be useful for families with recurrent miscarriage or known genetic risk	Results can be complex, especially with mosaic embryos
Can support informed reproductive decision-making	Requires IVF, embryo biopsy, and usually embryo freezing

Does PGT increase IVF success rates?

The answer is nuanced. In some groups, PGT may improve efficiency by helping prioritize embryos more likely to implant or less likely to miscarry. In other groups, especially younger patients with fewer embryos, the benefit may be less clear. The best evidence depends on patient age, diagnosis, embryo number, and the type of PGT used.

PGT Testing vs Prenatal Genetic Testing

A common misconception is that PGT replaces prenatal testing. It does not.

Feature	PGT Testing	Prenatal Genetic Testing
When it happens	Before embryo transfer during IVF	During pregnancy
What is tested	Embryo cells in the lab	Fetal DNA screening or fetal cells/tissue depending on the test
Main purpose	Embryo selection and risk assessment	Screening or diagnosing genetic conditions in an ongoing pregnancy
Examples	PGT-A, PGT-M, PGT-SR	NIPT, chorionic villus sampling, amniocentesis
Can it guarantee a healthy baby?	No	No single test can provide a complete guarantee

If pregnancy occurs after PGT, your OB-GYN or maternal-fetal medicine specialist may still discuss options such as NIPT, chorionic villus sampling (CVS), or amniocentesis, depending on your situation and preferences.

How PGT Results Are Used in Real Life

PGT results are one piece of the embryo selection puzzle, not the only one. Fertility specialists usually consider:

PGT result category
Embryo developmental stage and grading
Patient age and ovarian response
History of miscarriage or implantation failure
Whether the test was screening for chromosomes or a specific inherited disease
Whether any embryos are mosaic and how that mosaicism is classified

An embryo that tests euploid may be prioritized for transfer, but medical decisions still depend on the full clinical picture.

Cost and Practical Considerations

PGT testing can significantly increase the total cost of an IVF cycle. Charges may include:

Embryo biopsy fees
Genetic laboratory testing
Embryo freezing and storage
Additional counseling or custom assay setup for PGT-M

Insurance coverage varies widely. In some cases, partial coverage may apply when there is a documented inherited disease risk. In many cases, PGT remains an out-of-pocket expense.

It is worth asking the clinic for a detailed estimate before starting treatment.

Common Misconceptions About PGT Testing

“PGT guarantees a healthy baby.”

No. PGT can reduce certain known risks, but it cannot rule out every medical issue, developmental condition, or pregnancy complication.

“If an embryo is euploid, pregnancy is guaranteed.”

No. Implantation still depends on many factors, including uterine environment, embryo viability beyond chromosome count, and general reproductive health.

“PGT can fix male infertility.”

No. PGT does not improve sperm production or sperm function. It may help with embryo selection, but it does not treat the underlying male-factor issue.

“PGT and prenatal testing are the same thing.”

No. PGT happens before pregnancy is established. Prenatal testing happens during pregnancy and may be recommended even after PGT.

“All abnormal embryos are the same.”

No. Results vary by type and severity of abnormality. Mosaic findings are especially nuanced and should be reviewed with a specialist.

When to Talk to a Fertility Specialist or Genetic Counselor

You should consider professional evaluation if any of the following apply:

You or your partner have a known genetic condition or carrier status
There is a family history of a serious inherited disease
You have experienced recurrent miscarriage
You have had multiple unsuccessful IVF cycles or failed embryo transfers
A semen analysis or male infertility workup suggests a possible genetic component
You have been told you have a karyotype abnormality, balanced translocation, or Y chromosome deletion

For men especially, genetics can be an under-recognized part of fertility care. If severe male factor infertility is present, asking whether further genetic testing is appropriate can be an important next step.

Questions to Ask Your Doctor About PGT Testing

Which type of PGT are you recommending for us, and why?
How likely is PGT to change our treatment strategy?
Do we need carrier screening, karyotype testing, or genetic counseling first?
What are the clinic’s biopsy methods and lab standards?
How are mosaic embryos handled at this clinic?
What are the risks of no-result or inconclusive embryos?
How many embryos do you expect we may have available for testing?
What are the total costs, including freezing and storage?
Will prenatal testing still be recommended if we become pregnant?
How does male-factor infertility affect our options and expected outcomes?

Frequently Asked Questions About PGT Testing

Is PGT testing the same as genetic screening?

Not exactly. PGT is a broad term that includes both screening and targeted testing. PGT-A is generally considered a chromosome screening approach, while PGT-M targets a specific known inherited disorder.

What does PGT-A stand for?

PGT-A stands for preimplantation genetic testing for aneuploidy. It checks whether an embryo appears to have the usual number of chromosomes.

Can PGT testing tell if an embryo is healthy?

It can provide useful genetic information, but it cannot fully determine whether an embryo is “healthy” in every sense. It does not rule out all birth defects, developmental conditions, or pregnancy complications.

Does PGT testing improve live birth rates?

It may improve embryo selection efficiency in some patient groups, but the benefit is not identical for everyone. Outcomes depend on age, diagnosis, number of embryos, and the type of PGT used.

Can male infertility cause abnormal embryos?

Some forms of male infertility are associated with genetic or chromosomal issues that may affect embryo development or reproductive outcomes. This does not mean every man with abnormal semen parameters will have abnormal embryos, but genetics can be relevant in selected cases.

Should men with severe male factor infertility get genetic testing before IVF?

Often, yes, especially when sperm counts are very low, azoospermia is present, or there is a suspected chromosomal or inherited cause. Common evaluations may include karyotype testing, Y chromosome microdeletion testing, and carrier screening.

What is a mosaic embryo?

A mosaic embryo has a mix of cells with different chromosome results. Some may be normal and others abnormal. Mosaic findings are complex, and some mosaic embryos can still lead to successful pregnancies.

Is PGT testing 100% accurate?

No. PGT is highly advanced but not perfect. Results can be affected by sampling limitations, mosaicism, and the fact that only certain conditions are being assessed.

Do you still need prenatal testing after PGT?

Usually, yes. Many professional societies and clinicians still recommend discussing prenatal screening or diagnostic testing after conception, even if PGT was used.

Who should avoid PGT testing?

There is no single rule, but PGT may be less useful in some situations, such as when very few embryos are available or when the expected benefit is low. This is a personalized decision best made with a fertility specialist and, when appropriate, a genetic counselor.

References

American Society for Reproductive Medicine (ASRM). Committee opinions and practice guidance on preimplantation genetic testing and fertility care.
European Society of Human Reproduction and Embryology (ESHRE). Good practice recommendations for preimplantation genetic testing.
American College of Obstetricians and Gynecologists (ACOG). Guidance on preimplantation genetic testing and prenatal genetic screening/diagnosis.
Society for Assisted Reproductive Technology (SART). Patient resources on IVF, embryo testing, and fertility treatment.
National Institutes of Health (NIH) / MedlinePlus. Genetics and reproductive health educational resources.
Practice literature in peer-reviewed reproductive medicine journals, including Fertility and Sterility and Human Reproduction.