Preimplantation Genetic Testing During IVF
Preimplantation genetic testing (PGT) is a test performed on embryos created through in vitro fertilization (IVF) before they are transferred into the uterus. PGT may help identify certain genetic or chromosomal abnormalities that can affect implantation and pregnancy outcomes. Experts at University Hospitals are highly trained in PGT and use it as a tool to help people achieve their fertility goals.
Schedule a Fertility Consultation
A fertility consultation can help you better understand PGT and whether it should be a part of your IVF treatment journey.
To schedule a consultation with a University Hospitals Fertility Center expert, call 216-765-3352.
Quick Facts
- PGT tests IVF embryos for genetic and chromosomal health before transfer.
- There are three types of PGT: PGT-A (chromosome count), PGT-M (inherited conditions) and PGT-SR (chromosome structure).
- PGT is recommended for known genetic risk, recurrent miscarriage, advanced maternal age or unsuccessful IVF cycles.
- A small cell sample is taken from embryo, with results in around two weeks. Embryos are frozen after testing.
- PGT guides embryo selection but doesn’t guarantee a healthy pregnancy.
- UH offers all types of PGT, supported by genetic counselors and reproductive endocrinologists.
What Is PGT?
If you’re considering IVF, your doctor may suggest you consider preimplantation genetic testing as part of your IVF cycle. PGT involves taking a small sample of cells from each embryo to examine its genetic makeup. Analyzing these cells can identify chromosomal and genetic abnormalities that might affect implantation success or pregnancy outcomes. The information from PGT helps guide which embryo(s) may be the best choice to transfer.
It’s important to understand that PGT is not a treatment. It’s a diagnostic tool that gives you information about your embryos. PGT doesn’t change the embryos; it simply provides genetic information to help you and your care team make informed decisions about which embryo(s) to transfer.
What Does PGT Test For?
PGT can test for different types of genetic variations as well as chromosomal issues. Each type of PGT serves a different purpose, and the testing type that may be recommended for you is based on your individual circumstances, family history and risk factors. Your fertility specialist and genetic counselor will discuss which type of testing, if any, is appropriate for you.
- PGT-A (Aneuploidy Screening)
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PGT-A detects missing or extra chromosomes in embryos. Chromosomes are structures in our cells that carry genetic information. PGT-A detects missing or extra chromosomes, known as aneuploidy. When an embryo has an abnormal number of chromosomes, it often results in implantation failure, miscarriage or a chromosomal disorder.
Common chromosome abnormalities detected by PGT-A include Down syndrome (an extra copy of chromosome 21) and Turner syndrome (a missing copy of the X chromosome). PGT-A is the most commonly performed type of PGT, since identifying healthy embryos to transfer can, in some cases, improve the potential of IVF to result in a healthy pregnancy.
- PGT-M (Single-Gene Disorders)
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PGT-M tests for inherited genetic conditions that run in families and are carried by one or both parents. This testing is used when there is a known risk of passing on a genetic disease from parent to baby. Examples include Duchenne muscular dystrophy, cystic fibrosis and sickle cell disease. By identifying the embryos affected by these kinds of genetic conditions and instead choosing unaffected embryos to transfer, PGT-M helps prevent parents from transmitting genetic conditions to their baby.
- PGT-SR (Chromosomal Rearrangements)
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Some people have chromosome rearrangements in their cells, or pieces of chromosomes that are in a different order than typical. While these rearrangements may not affect a parent’s health, they can increase the risk of miscarriage or genetic disorders in their babies. PGT-SR detects these structural chromosome issues and helps identify embryos with a typical chromosome structure, reducing the risk of complications and supporting your chances of a healthy pregnancy.
When Is PGT Recommended?
PGT may be considered in several situations. It may be recommended when:
- You or your partner has a known genetic condition that could affect your children.
- You have experienced recurrent pregnancy loss.
- You are of advanced maternal age (typically 35 and older), which increases chromosomal abnormality risk.
- You have had previous unsuccessful IVF cycles.
The decision about whether to pursue PGT is individualized and best made through discussion with your fertility specialist and genetic counselor, who can review your specific circumstances and help you weigh the benefits and limitations.
How Does PGT Testing Work?
Understanding the PGT process helps you know what to expect during your IVF cycle.
Step 1: IVF and Embryo Development
Your IVF cycle begins with egg retrieval and fertilization in the laboratory. The resulting embryos develop in the lab for approximately five to six days until they reach the blastocyst stage, when they are ready for biopsy and testing.
Step 2: Embryo Biopsy
When embryos reach the blastocyst stage, a small number of cells are removed from the outer layer of the embryo (called the trophectoderm). This biopsy typically does not harm the embryo or impact its ability to develop, as the cells removed are not ones that form the fetus itself.
Step 3: Genetic Testing
The cells removed during biopsy are sent to a specialized genetics laboratory, where they are analyzed for chromosomal and/or genetic abnormalities using advanced testing methods. Results are typically available within two weeks, and embryos are frozen during this time.
Step 4: Embryo Selection
Based on test results, embryos are categorized as normal, abnormal or mosaic (a mix of normal and abnormal cells). Normal embryos have no detected abnormalities and are considered suitable for transfer. Your fertility specialist will discuss the results and recommend which embryo to transfer.
Step 5: Embryo Transfer
Once results are available and you and your care team have identified an embryo to transfer, your uterus will be prepared for transfer with hormone medications that support implantation. When your uterus is ready, the selected embryo is thawed and transferred into your uterus during a brief outpatient procedure.
What Results Are Expected for Each Test?
PGT test results can be normal, meaning that no chromosomal or genetic abnormalities were detected in the tested cells, or abnormal, meaning a chromosomal or genetic abnormality was detected. Depending on the type and severity of the abnormality, the embryo may not be recommended for transfer. Your fertility specialist and genetic counselor will discuss what the specific abnormality means and your options.
PGT results help guide embryo selection but do not guarantee a pregnancy will result or that a baby born from a tested embryo will be completely healthy. Genetic testing can detect many conditions but not all. Additionally, some embryos may have mosaicism, where some cells are normal and others are not. These require individual interpretation by your care team.
PGT and IVF Treatment Planning
PGT is performed only during IVF cycles. Because testing takes several weeks to complete, embryos are frozen while awaiting results. Once results are available, you and your fertility specialist will discuss which embryo to transfer in a future cycle.
PGT is one part of a comprehensive IVF treatment strategy and is not required or recommended for all IVF patients. Your specialist will explain both potential benefits and limitations of PGT, and whether it may be right for your situation.
Potential benefits of PGT include:
- May reduce the risk of miscarriage by identifying chromosomally abnormal embryos.
- May improve embryo selection by providing genetic information to guide transfer decisions.
- May prevent transmission of inherited genetic diseases to your children.
- May improve pregnancy outcomes in specific situations, such as advanced maternal age or recurrent pregnancy loss.
Limitations of PGT include:
- PGT cannot detect all genetic conditions or disorders.
- Results may not be 100 percent accurate; rare cases of false positives or false negatives can occur.
- The process adds cost and time to IVF treatment.
- PGT does not guarantee a healthy baby or successful pregnancy.
- Some embryos may be mosaic, making interpretation of results more complex.
Specialized Care for the LGBTQ+ Community
University Hospitals offers compassionate, collaborative care for the LGBTQ+ community, including fertility and reproductive health services for LGBTQ+ individuals and same-sex couples.
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Frequently Asked Questions About PGT
- What is PGT testing in IVF?
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PGT is a laboratory test performed on embryos created during IVF to evaluate their genetic and chromosomal health before transfer. A small sample of cells is taken from each embryo and analyzed to identify genetic or chromosomal abnormalities, helping to guide embryo selection for transfer.
- What does PGT test for?
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PGT can test for different types of genetic and chromosomal issues. PGT-A detects missing or extra chromosomes. PGT-M tests for inherited genetic conditions like cystic fibrosis or sickle cell disease. PGT-SR detects structural chromosome rearrangements. Your fertility specialist will recommend which type of testing, if any, is appropriate for your situation.
- Is PGT testing necessary for IVF?
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No. PGT is not required or recommended for all IVF patients. PGT may be recommended if you have a known genetic condition, a history of recurrent pregnancy loss, advanced maternal age, or previous unsuccessful IVF cycles. Your fertility specialist will discuss whether PGT is appropriate based on your individual circumstances.
- How accurate is PGT testing?
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PGT is generally accurate, but results are not 100% certain. Most results are reliable, but rare cases of false positives or false negatives can occur. Additionally, some embryos may have mosaicism, where some cells are normal and others are not, which can make interpretation more complex. Your care team will discuss what your specific results mean.
- Does PGT testing guarantee a healthy baby?
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No. PGT provides genetic information about embryos and can reduce the risk of certain conditions, but it does not guarantee a healthy baby or a successful pregnancy. PGT cannot detect all genetic conditions, and a baby born from a tested embryo could still have health issues or birth defects. PGT is one tool to help guide decision-making, not a guarantee of a healthy outcome.
- How long does PGT testing take?
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PGT results are typically available within two weeks after embryo biopsy. During this time, your embryos are frozen while awaiting results. Once results are available and you’ve had time to review them with your care team, a selected embryo can be thawed and transferred in a future cycle.
- What is the difference between PGT-A and PGT-M?
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PGT-A detects missing or extra chromosomes (aneuploidy), which are common causes of implantation failure and miscarriage. PGT-M tests for specific inherited genetic conditions carried by one or both parents, such as cystic fibrosis or sickle cell disease. PGT-A is used for general chromosome screening, while PGT-M is used when there is a known genetic risk in the family. Your fertility specialist will recommend which type of testing is appropriate for you.
What to Know About Fertility at Every Age
Family Planning for LGBTQIA+ People
The Path to Parenthood: Support for Your Fertility Journey
Related Resources and Next Steps
Your fertility care may involve additional treatments and services. Explore these resources to understand your full range of care options.
- In Vitro Fertilization (IVF): If PGT is recommended, it will be performed as part of an IVF cycle. Learn about IVF and how it works.
- Fertility Center Hub: Access all fertility services and resources at UH.
Schedule a Fertility Consultation
Understanding PGT and exploring whether it’s the right treatment for you is an important step in your fertility journey. University Hospitals provides comprehensive fertility care with experienced reproductive endocrinologists and personalized support throughout your treatment.
Ready to discuss PGT and your fertility goals?
To schedule a consultation with a University Hospitals Fertility Center expert, call call 216-765-3352.