Is Preimplantation Genetic Screening Required for IVF?

Preimplantation Genetic Screening (PGS) has become a widely discussed topic for couples undergoing IVF (In Vitro Fertilization). This advanced technique allows for embryo genetic testing before implantation, ensuring that only genetically healthy embryos are transferred into the uterus. But is it essential for every IVF case? Let’s explore the intricacies of preimplantation genetic screening, its advantages and limitations, and whether it is required for IVF success.

Understanding Preimplantation Genetic Screening

Preimplantation Genetic Screening (PGS) is a type of embryo genetic testing conducted before an embryo is implanted in the uterus during an IVF cycle. The goal is to identify genetically tested embryos that are free from chromosomal abnormalities, ensuring the transfer of the healthiest embryos. This method of chromosomal testing of embryos helps reduce the chances of miscarriages, failed IVF cycles, and the transmission of genetic disorders.

With advancements in IVF technology, embryo genetic screening is becoming an integral part of fertility treatments. In India, the adoption of IVF has been on the rise, with an estimated 250,000 IVF cycles conducted annually, as per a report by the Indian Society of Assisted Reproduction (ISAR). The need for preimplantation genetic screening has also increased, particularly among couples who have experienced recurrent miscarriages or have known genetic conditions.

What Is Genetic Testing of Embryos?

Genetic testing of embryos involves analyzing embryos for genetic and chromosomal abnormalities before they are implanted into the uterus. This process can detect a wide range of genetic disorders, including chromosomal abnormalities like Down syndrome and Turner syndrome, and genetic mutations such as cystic fibrosis and sickle cell anemia.

In India, the incidence of genetic disorders is relatively high, with around 1 in 20 couples at risk of passing on inherited genetic conditions. Embryo genetic screening offers a solution to couples facing such risks by identifying embryos that are chromosomally normal, which increases the likelihood of a healthy pregnancy and baby.

There are two types of genetic testing typically performed during IVF:

1. Preimplantation Genetic Diagnosis (PGD): PGD is used to detect specific genetic conditions in embryos, particularly when one or both parents are carriers of a known genetic disorder.
2. Preimplantation Genetic Screening (PGS): PGS is used to screen embryos for chromosomal abnormalities, ensuring that only embryos with the correct number of chromosomes are transferred.

Both types of testing aim to increase the chances of successful IVF by selecting genetically tested embryos that are free of significant genetic defects.

Is Genetic Testing Worth It for IVF?

The question many couples ask is whether preimplantation genetic screening is worth the added cost and complexity in an already challenging IVF process. The answer largely depends on the couple’s medical history and specific circumstances.

Benefits of Preimplantation Genetic Screening:

1. Improved Success Rates: PGS can increase IVF success rates by ensuring that only the healthiest embryos are transferred. For women over the age of 35, who have a higher risk of producing chromosomally abnormal embryos, PGS can be particularly beneficial.
2. Reduction in Miscarriages: In India, miscarriages affect a significant number of pregnancies, with around 15-20% of pregnancies resulting in a miscarriage. Chromosomal abnormalities are a major cause of miscarriage, and embryo genetic screening can help prevent this by selecting embryos that are chromosomally normal.
3. Lower Risk of Genetic Disorders: For couples with a history of genetic diseases or chromosomal issues, preimplantation genetic screening offers peace of mind by reducing the risk of passing on genetic conditions to their offspring.
4. Optimizing the Use of Embryos: By identifying chromosomally normal embryos, PGS allows for better decision-making in terms of embryo transfer, reducing the need for multiple IVF cycles and improving the chances of a successful pregnancy in the first attempt.

Given these advantages, embryo genetic testing can be highly beneficial, particularly for couples with a history of genetic disorders, advanced maternal age, or recurrent pregnancy loss. However, for couples with no known risk factors, the decision to undergo preimplantation genetic screening may not be as clear-cut.

Can You Genetically Test Fresh Embryos?

Yes, preimplantation genetic screening can be performed on fresh embryos. In many cases, however, fertility clinics prefer to freeze embryos after embryo genetic testing to allow time for a thorough analysis. The freezing of embryos (vitrification) enables the clinic to test the embryos for genetic abnormalities without the pressure of a fresh embryo transfer schedule. This approach also allows for better synchronization of the embryo transfer with the optimal condition of the uterus.

While fresh embryos can be genetically tested, frozen embryo transfer is often preferred because it gives both the embryos and the patient’s body time to recover, leading to improved IVF outcomes.

When Is Embryo Transfer After Genetic Testing?

Embryo transfer typically occurs after preimplantation genetic screening is completed and genetically tested embryos have been identified. This screening is conducted during the blastocyst stage, which usually occurs around 5 to 7 days after fertilization in the lab. If the embryos have been frozen after testing, the transfer can take place in the next IVF cycle. The timing of the transfer depends on factors like the patient’s uterine health and the results of the embryo genetic screening.

In many Indian clinics, frozen embryo transfers (FET) are becoming more popular because they allow for better planning and increased flexibility in coordinating the transfer with the woman’s natural cycle. The procedure itself is similar to a fresh embryo transfer and is performed within 3-5 days after the thawing of the embryos (meaning they are slowly warmed to restore them to their normal state for implantation).

How Accurate Is Embryo Testing?

Preimplantation genetic screening is known for its high accuracy, with a reported accuracy rate of 95-98%. This means that most chromosomal abnormalities can be detected, ensuring that only healthy embryos are transferred. However, it’s important to note that no test is completely foolproof, and there is always a slight risk that some chromosomal abnormalities may go undetected.

In India, clinics that offer chromosomal testing of embryos use advanced techniques like Next-Generation Sequencing (NGS), which provides a high level of precision in detecting chromosomal abnormalities. NGS is now the most commonly used method for preimplantation genetic screening in Indian fertility clinics.

What Is the Success Rate of IVF with Genetic Testing?

The success rate of IVF increases significantly with preimplantation genetic screening. In India, where IVF success rates generally range from 35-45%, incorporating embryo genetic screening can boost these rates by 10-20%. The use of genetically tested embryos is particularly beneficial for older women and those with a history of failed IVF cycles or recurrent miscarriages.

According to studies, women over 35 who undergo IVF with preimplantation genetic screening have a higher chance of success compared to those who do not opt for genetic testing. The screening helps eliminate chromosomally abnormal embryos, which are more common in older women, improving the overall IVF outcome.

What Are the Disadvantages of Embryo Screening?

Despite the many benefits, embryo genetic screening is not without its drawbacks. The main disadvantages include:

1. High Cost: The cost of preimplantation genetic screening can add significantly to the overall expense of an IVF cycle. In India, PGS costs range between INR 1.5 lakh to INR 2.5 lakh per cycle, in addition to standard IVF costs. For many couples, the high cost of embryo genetic testing can be a major barrier.
2. Invasiveness: While the technology for genetic testing has advanced, there is still a small risk of damaging the embryos during the biopsy process. This risk is low but should be considered when opting for preimplantation genetic screening.
3. Emotional Stress: For couples hoping to use all their embryos, discovering that many embryos are not genetically viable can be emotionally difficult. Embryo genetic screening can result in fewer embryos being eligible for transfer, which can be disheartening for those already facing fertility challenges.
4. Fallible: As with any medical test, preimplantation genetic screening is not 100% accurate, and some chromosomal abnormalities may still go undetected. While the accuracy rate is high, couples should be aware of this limitation.

How Much Does Genetic Testing Cost for Embryos?

The cost of embryo genetic testing in India varies depending on the clinic and the specific tests conducted. On average, preimplantation genetic screening costs between INR 1.5 lakh to INR 2.5 lakh per cycle. This is in addition to the standard cost of IVF, which ranges from INR 1.5 lakh to INR 3 lakh per cycle, making the total cost of IVF with genetic testing quite high.

For many couples, the cost of embryo genetic screening is a major factor in deciding whether to pursue it. However, considering the potential for improved success rates and reduced risk of miscarriage, many find the additional expense to be worthwhile, especially in high-risk cases.

Is Genetic Testing on Embryos Safe?

Yes, embryo genetic screening is generally considered safe. The biopsy procedure used to extract cells from the embryo for testing has been refined over the years, reducing the risk of harm to the embryos. In India, most fertility clinics follow strict protocols to ensure the safety and viability of the embryos during the testing process.

While there is a minimal risk associated with the biopsy, the benefits of identifying genetically tested embryos often outweigh the risks. However, couples should be aware of the risks and benefits and also discuss it with their fertility specialist to make an informed decision.

Conclusion

The decision to undergo preimplantation genetic screening ultimately depends on the individual circumstances of the couple undergoing IVF. For couples with a history of genetic disorders, recurrent miscarriages, or advanced maternal age, embryo genetic testing can significantly improve IVF outcomes and increase the chances of a successful pregnancy.

In India, where fertility treatments are becoming more accessible and the demand for IVF is growing, preimplantation genetic screening offers a promising way to optimize the IVF process. While the cost of embryo genetic screening can be high, the potential benefits in terms of increased success rates, reduced miscarriages, and healthier pregnancies make it a valuable option for many couples.

For those considering IVF, discussing the option of preimplantation genetic screening with a fertility specialist can provide a clearer understanding of whether it’s the right choice for their unique situation.

FAQ:

1. Does Genetic Testing of Embryos Rule Out Down Syndrome?

Yes, genetic testing of embryos, specifically Preimplantation Genetic Testing for Aneuploidy (PGT-A), can detect chromosomal abnormalities, including Down syndrome, which is caused by an extra copy of chromosome 21. By screening embryos for chromosomal abnormalities before implantation, PGT-A can help reduce the risk of transferring embryos with Down syndrome.

2. What To Do If All Embryos Are Abnormal?

If all embryos are found to be abnormal after preimplantation genetic screening (PGS), the next steps should be discussed with your fertility specialist. Options may include:

• Another IVF cycle to create new embryos.
• Donor eggs or sperm if the abnormality is suspected to be linked to the reproductive cells.
• Adoption or reconsidering other family-building options.

3. Does PGT Testing Tell You Gender?

Yes, PGT testing can reveal the gender of the embryos. Since preimplantation genetic testing (PGT) analyzes the chromosomes of the embryo, it can determine whether the embryo has XX (female) or XY (male) sex chromosomes. However, in some countries, selecting embryos based on gender is regulated or restricted.

4. Does Preimplantation Genetic Screening Reduce Miscarriage?

Yes, preimplantation genetic screening (PGS) can help reduce the risk of miscarriage by identifying embryos with chromosomal abnormalities that are more likely to result in miscarriage. By transferring only genetically tested embryos that are chromosomally normal, the chances of a successful pregnancy are increased, and the risk of miscarriage is lowered.