What is preimplantation genetic testing (PGT) and how does it work? What are the risks and benefits? How much does it cost? Can it help me have a healthier baby? Does PGT reduce the risk of miscarriage?
As a genetic counselor at Illume Fertility, my role is to help patients get answers questions like these so they can better understand genetic testing and the information it provides. Let's dive into the world of genetics together to learn more!
In this article:
- What is preimplantation genetic testing (PGT)?
- How does PGT work?
- Are there different types of genetic testing for embryos?
- What issues can PGT identify?
- How much does PGT cost?
- Who should consider preimplantation genetic testing?
- Genetic Testing vs Embryo Testing
- FAQs About Preimplantation Genetic Testing
- Want to speak with a genetic counselor?
- More Resources
What is preimplantation genetic testing (PGT)?
Preimplantation genetic testing (PGT) is the process of screening a small sample of cells from embryos for genetic abnormalities and chromosomal disorders. This is elective screening that some fertility patients choose to have performed in conjunction with in-vitro fertilization (IVF), prior to embryo transfer.
Advances in the field of reproductive medicine and technology have expanded the ways in which we can help each patient have the very best chance of success with IVF. PGT can be a helpful tool for determining which embryo to transfer, reduces the risk of miscarriage, helps parents avoid passing down genetic disorders, and provides a general assessment of each embryo's potential.
How does preimplantation genetic testing work?
The exact methodology behind PGT varies from lab to lab, but the overall process remains the same.
Once an embryo reaches Day 5 or 6 of development (called the blastocyst stage), a small portion of cells is taken from the outer edge of the embryo (the trophectoderm, which will go on to become the placenta).
The cells that were taken are then sent off for testing while the embryos are left here at Illume Fertility, under our constant supervision and care. The lab performing the embryo testing will then check the embryos for any chromosomal abnormalities or specific genetic conditions, depending on the type of test ordered.
Results are then delivered to your doctor and genetic counselor, who help interpret any findings and offer guidance about what to do next.
Learn more about embryo development:
Are there different types of genetic testing for embryos?
IVF, TTC, ICSI, TWW...there are lots of acronyms used in the world of fertility, which can get confusing. So before we begin, let's define a few different terms you may hear when we talk about the genetic testing of embryos.
Preimplantation Genetic Testing for Aneuploidies (PGT-A)
PGT-A identifies aneuploidy, the term used to describe any embryo with either too many or too few chromosomes (or large extra or missing pieces of chromosomes). One form of aneuploidy causes Down Syndrome, and other chromosomal changes may cause up to 60% of miscarriages or prevent pregnancy altogether.
Preimplantation Genetic Testing for Monogenic/Single-Gene Disorders (PGT-M)
PGT-M tests for monogenic (single gene) disorders, such as Cystic Fibrosis, Huntington’s disease, Sickle Cell Anemia, muscular dystrophy, and hemophilia – detection that is especially important for people who know their families carry the defective gene.
Preimplantation Genetic Testing for Chromosomal Structural Rearrangements (PGT-SR)
PGT-SR looks for structural rearrangements, when a parent is known to carry a chromosome change such as a translocation or inversion. These can cause extra or missing chromosomal material in embryos.
Note: You may occasionally see the terms Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS). PGS is the old term for PGT-A and PGD is the old term for PGT-M. These terms are not commonly used anymore and are considered outdated.
What issues can PGT identify?
PGT can identify an abnormal number of chromosomes in an embryo, or structural rearrangements that could prevent successful outcomes. PGT can also identify the presence of more than 4,000 single-gene disorders, including cystic fibrosis, spinal muscular atrophy, and fragile X in patients who are found to be carriers of one of these genetic mutations.
The main issues PGT-A can detect are extra or missing chromosomes in an embryo. These can cause well-known conditions like Down syndrome or more obscure things. Another benefit of PGT-A is that we can uncover common reasons for a woman to not get pregnant or lose a pregnancy early on (typically when the embryo has extra or missing chromosomes of any kind).
The other two types of PGT (-M and -SR) are used to detect other issues.
1. PGT-A can determine which embryos have a normal number of chromosomes so you can transfer them in a specific order to hopefully increase your chances of a successful pregnancy and healthy baby.
2. PGT-M is used to look for specific known genetic conditions in the family or conditions that were found on your (or your partner's) genetic carrier screening.
3. PGT-SR is used to look for specific known chromosomal structural rearrangements that may lead to an embryo having partial, extra, or missing chromosome(s).
How much does PGT cost?
The cost of PGT varies from lab to lab. Typically, it costs around $350-$400 per embryo, but the total cost varies depending on the lab you choose to perform the testing. The cost also increases when including shipping.
Illume Fertility partners with both Igenomix and Genomic Prediction, whose bundled cost is $380 per embryo (includes shipping, biopsy and embryo testing). We also partner with NextGen, whose average costs (including shipping, biopsy and embryo testing) are typically around $500+ per embryo. Another cost to factor in is embryo cryopreservation (freezing), which is necessary for PGT.
Want a little good news? Some insurance companies are now covering PGT-A (for example, Progyny and Stork Club, who are the infertility benefit administrators for some insurance groups).
While we understand it can be tough to justify the cost of genetic testing and consulting with a genetic counselor, it can make all the difference for some patients. We encourage you to talk to your doctor to see if PGT is recommended for your specific situation.
Note: At Illume Fertility, we pair each patient with an Insurance & Billing Advocate who are experts in fertility costs and insurance coverage. We know how frustrating it can be to navigate the financial aspect of infertility, and we're here to help you find a way to get the care you need. We also offer a variety of self-pay plans to help you reach your goals. Explore our Opportunity Plans here.
Don't have coverage for infertility?
Genetic Testing vs Embryo Testing
When you enter the world of infertility, you'll soon discover that there are a lot of tests involved. Fertility testing, genetic testing, embryo testing...what's the difference?
- Fertility testing refers to the series of diagnostic tests your fertility doctor will order before you begin fertility medications or other treatment (if required). This helps your doctor pinpoint your individual fertility challenges and plan out the best course of action for your situation. Learn more here.
- Genetic testing can be performed on either the parent(s)-to-be or their embryos. Genetic testing for parents-to-be involves bloodwork that is often referred to as genetic carrier screening. Genetic testing for embryos is more commonly referred to as preimplantation genetic testing (PGT). Learn more here.
- Embryo testing is a general term that refers to the screening of embryos for chromosomal or structural abnormalities or specific genetic conditions (the focus of this article).
Who should consider preimplantation genetic testing?
PGT-A is offered to most patients who do IVF. With that said, it is not necessarily imperative for all patients doing IVF to complete this testing.
The main reason to do PGT-A is to find out which embryos have extra or missing chromosomes. This can then help prioritize which embryos should be transferred in order to maximize your chances of getting pregnant.
The reason this is important is that embryos with extra or missing chromosomes often result in no implantation or an early miscarriage (often before 10 weeks). It can also result in Down syndrome or more severe conditions like Edward’s syndrome (also referred to as Trisomy 18) and Patau syndrome (also referred to as Trisomy 13) which can cause severe medical or developmental issues and be fatal.
PGT-SR is only offered in very specific circumstances where there is a known translocation or inversion, and PGT-M is only offered on a case by case basis, when indicated by family or medical history.
Over 35? The chance for extra or missing chromosomes increases as a woman gets older. Preimplantation genetic testing is more strongly recommended for women over the age of 35, as they have significantly higher chances of having embryos with extra or missing chromosomes. However, younger individuals can always opt to do this testing as well.
In short, if you:
- have a family history of a genetic disorder or medical condition
- have a known translocation or inversion
- are over 35 and want to increase your odds of success
- want to try and avoid miscarriages or unsuccessful embryo transfers
- want to screen for chromosomal abnormalities
...PGT may be worth looking into!
Always speak to your doctor or genetic counselor about what's best for your personal situation.
FAQs About Preimplantation Genetic Testing
Wondering about something we haven't covered above? Here are some of the most common questions we hear about PGT and what we tell our patients:
Does PGT reduce the risk of miscarriage?
Yes, PGT can reduce the risk of pregnancy loss by screening for chromosomal abnormalities, which are a common cause of miscarriage. Studies have shown dramatic decreases in miscarriage rates after IVF when PGT-A is performed as part of the process.
Want to dig deeper? Check out this video that breaks down PGT-A statistics and study findings.
Get miscarriage support & resources:
Will PGT harm my embryos?
It's very unlikely, but there's around a 1% chance of disruption to the embryo when PGT is performed. It is important to note that children born from embryos that have undergone PGT are typically not expect to have significant issues. However, the process of removing some cells from the embryo can, in rare cases, cause damage that can result in an embryo failing to implant.
Your doctor or genetic counselor should always review all risks and answer any questions you may have about PGT prior to performing any tests.
What if all my embryos come back abnormal?
One unintended side effect of PGT is that you may end up finding out you have no viable embryos and need to do a second IVF cycle. This can be very frustrating, even knowing it is likely none of your embryos would have resulted in a healthy pregnancy.
If this happens, your genetic counselor and the rest of your Care Team will always discuss next steps and offer any resources they have to offer to ensure you get the best chance at a successful next cycle.
Remember: Our fertility counselors are a great resource for patients navigating challenging test results, setbacks or losses, and we encourage you to reach out if you'd like that additional support.
Can previously frozen embryos undergo PGT?
While PGT can be performed on previously frozen embryos, it is not ideal. The process of thawing, refreezing, and re-thawing is incredibly stressful for embryos and can cause a significant decrease in success rates.
How long do PGT results typically take to come back?
PGT results typically take around two weeks to come back. However, this typically does not add time to your journey as the majority of IVF patients choose to do a frozen embryo transfer, which means there is already a waiting period as the woman’s hormone levels return to normal (prior to transfer).
What is a mosaic embryo?
The term "mosaic" means mixed. Mosaic embryos are embryos that have a mix of chromosomally normal and chromosomally abnormal cells. There are a number of ways in which an embryo can become mosaic. While mosaic embryos have limited potential compared with euploid embryos, they still can result in a healthy baby. It is important to discuss the possibility of transferring a mosaic embryo with your doctor or genetic counselor.
How can PGT help reduce the chance of multiples?
By knowing which embryos are chromosomally normal and most likely to result in a successful pregnancy, you can more confidently transfer a single embryo, instead of transferring two (or more) embryos.
At Illume Fertility, our goal is to help you have one healthy baby at a time. While twins or higher order multiples are sometimes a welcome surprise (as a result of a natural embryo split), our team almost always recommends elective single embryo transfer (ESET), which significantly reduces the chance of multiples and lessens risks for both mother and baby.
How accurate is PGT?
While PGT is as a hugely important tool in fertility treatment, it is not a perfect process. There are a small number (fewer than 1-2%) of misdiagnoses from PGT (meaning either false positives or false negatives). Overall, it is typically very accurate and can be a helpful tool for many patients.
Ready to speak with a genetic counselor?
Illume Fertility has two certified genetic counselors on staff: Jamie Speer, and myself, Anthony Porto. You can learn more about our full team of care providers here. We work with patients every day to identify genetic concerns and find the best solutions for each family.
We're here to help! To schedule a consultation and start your journey, reach out to us today.
Want more information?
If you're curious to learn more about genetic testing (for either parents-to-be or embryos), fertility testing or other topics related to fertility, check out the following articles and videos:
- PGT: Embryo Screening for Improved IVF Success
- How IVF and Genetic Testing Can Help Prevent Sickle Cell Anemia
- Fertility Testing FAQs | The First Steps of Family Building
- Explore our Integrated Fertility & Wellness Program
- Meet our Fertility Care Team
- Read Patient Stories
- Watch Ask Monica Q&A Video Series
Anthony Porto, M.S., LCGC is a genetic counselor at Illume Fertility. Porto earned his Masters in Genetic Counseling from Northwestern University and is a member of the National Society of Genetic Counselors (NSGC) and NSGC’s Assisted Reproductive Technologies/Infertility SIG.