How Pre-implantation Genetic Testing (PGT) Boosts IVF Success?
29 July 2024How Pre-implantation Genetic Testing (PGT) Boosts IVF Success?
In Vitro Fertilization (IVF) is a well-known assisted reproductive technology that has brought joy to countless couples struggling with infertility. However, even with IVF, achieving a successful pregnancy can sometimes be challenging due to genetic abnormalities in embryos. This is where Pre-implantation Genetic Testing (PGT) comes into play. PGT is an advanced technique that screens embryos for genetic disorders before implantation, significantly improving the chances of a successful pregnancy. This blog will delve into the details of PGT, its benefits, the process involved, and answer some frequently asked questions.
Understanding Pre-implantation Genetic Testing (PGT)
What is PGT?
Pre-implantation Genetic Testing (PGT) is a procedure used to identify genetic defects in embryos created through IVF before pregnancy. It involves taking a biopsy from the embryo and analyzing it for chromosomal abnormalities or specific genetic conditions. This ensures that only genetically normal embryos are selected for transfer to the uterus.
Types of PGT:
- PGT-A (Pre-implantation Genetic Testing for Aneuploidies): This test screens embryos for abnormal numbers of chromosomes, which can lead to conditions like Down syndrome, Turner syndrome, and other chromosomal abnormalities.
- PGT-M (Pre-implantation Genetic Testing for Monogenic/Single Gene Defects): This test identifies specific genetic disorders caused by mutations in a single gene, such as thalassemia, cystic fibrosis, sickle cell anemia, and Huntington’s disease.
- PGT-SR (Pre-implantation Genetic Testing for Structural Rearrangements): This test detects structural rearrangements in chromosomes, such as translocations and inversions, which can cause genetic disorders or affect embryo viability.
What are Mosaic Embryos?
Mosaic embryos are embryos that contain both normal and abnormal cells. This condition, known as mosaicism, occurs when some cells within the embryo have the correct number of chromosomes while others do not. During the early stages of embryonic development, errors in cell division can lead to this mixture of chromosomally normal and abnormal cells. Mosaic embryos can present a unique challenge in IVF because their potential to develop into a healthy pregnancy is uncertain. However, advances in genetic testing have made it possible to identify and analyze mosaic embryos, providing valuable information for making informed decisions about their use in IVF treatment.
The Process of PGT in IVF
Step-by-Step Process:
- Ovarian Stimulation and Egg Retrieval: The IVF cycle begins with the woman undergoing ovarian stimulation using hormone medications. The goal is to stimulate the ovaries to produce multiple eggs.Once the eggs are mature, they are retrieved from the ovaries using a minor surgical procedure called follicular aspiration.
- Fertilization: The retrieved eggs are then fertilized with sperm in a laboratory dish. This can be done through conventional insemination (placing sperm near the egg) or through Intracytoplasmic Sperm Injection (ICSI), where a single sperm is injected directly into an egg.
- Embryo Culture: Fertilized eggs (now embryos) are cultured in a controlled laboratory environment. The embryos are monitored for their development and progression.
- Embryo Biopsy: At around day 5-6 of development, when embryos typically reach the blastocyst stage (consisting of about 100 – 300 cells), a few cells (usually 5-10) are carefully removed from each embryo. This process is known as embryo biopsy and is performed using specialized techniques to ensure minimal impact on the embryo.
- Genetic Analysis (PGT): The biopsied cells are sent to a genetic laboratory where they are analyzed to detect genetic or chromosomal abnormalities.
- Embryo Selection:Based on the results of the genetic analysis, embryos that are determined to be chromosomally normal (or free of the specific genetic disorder being screened for) are selected for transfer. This helps maximize the chances of a successful pregnancy and reduces the risk of miscarriage.
- Embryo Transfer:The selected embryo(s) are transferred into the woman’s uterus. This procedure is typically done 5-7 days after fertilization, depending on the stage of embryo development.The number of embryos transferred depends on various factors, including the woman’s age, embryo quality, and the clinic’s protocols.
Benefits of PGT in IVF
- Increased success rates: By selecting embryos free from genetic abnormalities, PGT significantly increases the chances of a successful pregnancy and reduces the risk of miscarriage.
- Reduction in miscarriages: Chromosomal abnormalities are a common cause of miscarriage. PGT helps identify and avoid transferring embryos with these abnormalities, thereby reducing the risk of miscarriage.
- Lower risk of genetic disorders: PGT allows for the detection of specific genetic conditions, ensuring that only embryos without these disorders are selected for transfer. This reduces the risk of genetic diseases in the baby.
- Enhanced pregnancy outcomes: By transferring only genetically screened embryos, PGT can lead to better pregnancy outcomes, including higher implantation rates and healthier pregnancies.
Candidates for PGT
Who should consider PGT?
- Couples with a history of genetic disorders.
- Women of advanced maternal age. (over 35 years)
- Couples with repeated IVF failures or recurrent miscarriages.
- Couples with a history of chromosomal abnormalities.
- When either partner has chromosomal translocation
Criteria for PGT Eligibility: Your fertility specialist will assess your medical history, genetic background, and specific circumstances to determine if PGT is appropriate for you.
Risks and Limitations of PGT
Potential Risks:
- Embryo biopsy is a delicate procedure and carries a small risk of damaging the embryo.
- Genetic testing is highly accurate but not infallible. There is a small chance of approx (2%) of false positives or negatives.
- PGT may not detect all genetic abnormalities.
- There is a possibility that embryo may self correct any abnormalities, although not definitely proven
Limitations and Considerations:
- PGT is an additional step in the IVF process and adds to the overall cost.
- Not all embryos will be suitable for biopsy and testing.
- Ethical and emotional considerations regarding the fate of non-selected embryos.
- PGT is a method of screening & selection of available embryos, if there are very less suitable embryos for transfer PGT may not improve success chances.
Conclusion
This comprehensive guide should help you understand how Pre-implantation Genetic Testing can improve IVF success rates. If you have more questions or need personalized advice, consult with your fertility specialist. For more information or to schedule a consultation, please contact Bavishi Fertility Institute today.
Author Bio
Dr. Parth Bavishi
Dr. Parth Bavishi, MD in Obstetrics and Gynecology, brings over 12 years of invaluable work experience to his role as Director of Bavishi Fertility Institute, leading a group of IVF clinics committed to helping couples realise their dreams of parenthood.
Bavishi Fertility Institute is dedicated to provide customised and personalised treatments which are simple, safe , smart and successful. Bavishi Fertility Institute works with success and satisfaction for all at heart. Providing an ideal blend of professional treatment and personalised care.
Dr. Parth had special training in infertility at Bavishi fertility Institute, the Diamond Institute, USA, and the HART Institute, Japan.
Dr. Bavishi is a distinguished expert in his field. In addition to his clinical practice, Dr.Bavishi is the author of the acclaimed book, ‘Your Miracle in Making: A Couple’s Guide to Pregnancy,’ offering invaluable insights to couples navigating the complexities of fertility. He loves to empower patients to make the correct choice by education both online and offline .
His exceptional contributions have earned him the prestigious Rose of Paracelsus award from the European Medical Association. Dr.Parth has been an invited faculty at many national and international conferences.
Beyond his professional endeavors, Dr.Bavishi is an avid traveler who finds solace in exploring new destinations. He also enjoys engaging his mind with brainy puzzles, always seeking new challenges and solutions outside of the medical realm.
FAQs
PGT is highly accurate, with a success rate of over 95% in detecting genetic abnormalities. However, it is not 100% accurate , and some genetic conditions may still go undetected.
While PGT significantly reduces the risk of genetic disorders and increases the chances of a successful pregnancy, it does not guarantee a healthy baby. Other factors such as maternal health and pregnancy complications also play a role. PGT is unable to diagnose single gene diseases for which prior information is not available.
PGT adds to the overall cost of IVF due to the additional testing and laboratory procedures required. However, it can potentially save costs in the long run by increasing the chances of a successful pregnancy and reducing the need for multiple IVF cycles.
The PGT process typically takes about 1-2 weeks from the time of embryo biopsy to receiving the genetic analysis results. This timeframe may vary depending on the clinic and the specific testing being performed.
At Bavishi Fertility Institute it is possible to expedite the results and have the result in 24 hrs.
PGT can detect many, but not all, genetic disorders. It is most effective for known genetic conditions and chromosomal abnormalities. Rare genetic disorders or mutations that are not specifically tested for may go undetected. Doctors can tell when diagnosis is possible and when it is not depending on the type of genetic problem
Embryos that are not selected due to genetic abnormalities or other reasons can be discarded, donated to research, or, in some cases, frozen for future use if deemed healthy for other potential transfers.
Ethical concerns with PGT include the potential for selecting embryos based on desired traits (designer babies), the fate of non-selected embryos, and the accessibility of this technology. It’s important to discuss these concerns with your fertility specialist.
PGT is not necessary for all IVF patients. It is recommended for those with specific risk factors or medical histories that indicate a higher likelihood of genetic abnormalities.
Consulting with a fertility specialist can help determine if PGT is right for you based on your medical history, genetic background, and specific fertility challenges.
PGT can be performed on most embryos, but not all embryos may reach the necessary stage for biopsy. Some embryos may not develop to the blastocyst stage required for testing.
By selecting the healthiest embryos for transfer, PGT can increase the chances of a successful pregnancy in the first embryo transfer, potentially reducing the need for multiple IVF transfers.
The decision to use or transfer mosaic embryos depends on several factors, including the degree of mosaicism and the specific chromosomes involved. Some studies suggest that certain mosaic embryos can still result in healthy pregnancies, although the success rates may be lower compared to fully normal embryos. It is crucial to consult with a fertility specialist to evaluate the specific genetic findings and discuss the potential risks and benefits. In some cases, transferring mosaic embryos may be considered when no fully normal embryos are available, but this decision should be made with careful consideration and thorough genetic counseling.
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