What if we could find out if an embryo is genetically healthy before transfer in an assisted reproduction treatment? The answer has completely transformed our understanding of contemporary reproductive medicine.
Preimplantation genetic diagnosis, also known as PGT (or PGD), is a tool that allows for the study of embryos obtained through in vitro fertilization before they are transferred to the uterus. Its purpose is to detect chromosomal or genetic abnormalities that could jeopardize the viability of the pregnancy or the long-term well-being of the baby.
However, there is much more to this technical definition. Particularly in the case of surrogacy, which involves the intended parents, the medical team, and, often, a surrogate who trusts that everything will be carried out with the utmost scientific rigor.
In this article, we will address in detail what preimplantation genetic diagnosis (PGD) is, when it is performed, what it entails, and what its implications are. This content will be useful for understanding one of the most relevant foundations of contemporary reproductive medicine if you are considering reproductive options.
What exactly is preimplantation genetic diagnosis?
Preimplantation genetic diagnosis (PGD) is a procedure that complements in vitro fertilization (IVF) and can only be performed once the embryos have been created in the laboratory. To examine their genetic information, they need to be tested before being transferred to the uterus. In other words, it is an evaluation performed before pregnancy begins that provides a better understanding of the embryo’s viability.
Its primary objective is to analyze embryonic genetic material to detect any irregularities. These changes can include variations in the number of chromosomes, as occurs in monosomies or trisomies; modifications in chromosome structure; genetic diseases caused by the mutation of a single gene; or, in some cases, factors related to genetic compatibility. In other words, this method facilitates the selection of embryos that are most likely to implant successfully and develop healthily.
This analysis is even more crucial in surrogacy. It’s not just about increasing success rates, but also about minimizing risks for the future baby and providing greater medical security for the surrogate. Each transfer represents a significant investment, both emotionally and physically, so optimizing the odds from the outset is of paramount importance.
To truly understand the importance of preimplantation genetic diagnosis, one must consider a biological fact: not all embryos are genetically viable, even when the sperm and eggs come from healthy individuals with no significant medical history. A significant proportion of miscarriages and implantation failures in the early stages of pregnancy are caused precisely by chromosomal irregularities that occur spontaneously during cell division. In many cases, there is no inherited disease involved, but rather a random biological error.
This is where this technique makes a significant difference. By examining the embryo before transfer, it’s possible to decrease the risk of miscarriage, increase implantation rates, and avoid numerous unsuccessful attempts. It also allows for the transfer of a single embryo with a higher probability of success, thus reducing the risk of multiple pregnancies and related complications.
This means that, in a surrogacy procedure, there are fewer medical risks, less emotional strain, and a greater sense of control for everyone involved. Because every informed decision matters when it comes to assisted reproduction.
How is preimplantation genetic diagnosis performed? And what types are there?
The preimplantation genetic diagnosis process is carried out following a meticulous and highly precise sequence. Nothing is left to chance, as each phase is designed to acquire as much information as possible without jeopardizing the embryo’s viability. It all begins with in vitro fertilization. During this stage, the eggs are retrieved and fertilized with the corresponding sperm in the laboratory, either from one of the intended parents or from a donor. From then on, the embryos begin their development under very rigorous monitoring.
These embryos are cultured for about five or six days until they reach the blastocyst stage . This is a crucial phase of embryonic development, in which the embryo already has hundreds of differentiated cells and a more complex structure. This stage allows for a more precise analysis with less impact. It is at this point that the embryo biopsy is performed. A few cells are carefully taken from the trophectoderm , which is the area of the embryo responsible for developing the placenta. The inner cell mass, which will give rise to the baby in the future, remains intact. When the process is properly understood, this aspect is essential and tends to provide reassurance.
The cells obtained are sent to a specialized laboratory, where their DNA is examined using sophisticated molecular genetics methods. Depending on the type of analysis recommended in each situation, these studies allow for the identification of specific mutations or chromosomal abnormalities.
The embryos are preserved through vitrification, a very rapid freezing method that ensures their viability, while the analysis is carried out. Once the results have been obtained, the medical team can choose the most suitable embryo for transfer.
This process facilitates informed decision-making before starting a pregnancy, which is particularly relevant in surrogacy, since each attempt requires medical coordination, planning, and a significant emotional investment.
It is essential to understand that not all genetic testing is the same. Preimplantation genetic diagnosis includes several types that are tailored to the specific clinical needs of each individual or couple.
The PGT-A test, for example, is designed to identify abnormalities in the number of chromosomes, also called aneuploidies . It is generally recommended to determine embryos with normal chromosomes, especially when the mother is of advanced maternal age, has had recurrent miscarriages, or previous implantation failures.
In contrast, PGT-M is used when there is a risk of transmitting a specific monogenic disease , such as muscular dystrophy or cystic fibrosis. In these situations, the analysis is planned with the intention of finding that specific mutation.
Finally, PGT-SR is recommended when one of the parents has a structural alteration in their chromosomes, which could have a negative impact on the development of the embryo.
When is it recommended to perform a PGD?
Not all couples or individuals need to use this technique. However, it is often recommended in specific situations:
- Advanced maternal age.
- Recurrent miscarriages.
- Previous implementation failures.
- Family history of genetic diseases.
- Known carriers of specific mutations.
- Chromosomal abnormalities in one of the parents.
In surrogacy, many clinics recommend preimplantation genetic diagnosis even without a clear history, as the aim is to maximize the probability of success in each transfer.
The scope of preimplantation genetic diagnosis always depends on the type of test ordered. Not all tests analyze the same things or look for the same abnormalities; each one addresses a specific clinical need.
When an analysis is performed to detect chromosomal abnormalities, it is possible to identify conditions such as trisomy 21, associated with Down syndrome, as well as trisomy 18 or trisomy 13. It can also detect conditions such as Turner syndrome, which involves an alteration in one of the sex chromosomes. These abnormalities are usually related to problems with the number of chromosomes and, in many cases, directly affect the viability of the pregnancy.
In studies targeting monogenic diseases , the approach is different. Here, a specific mutation in a particular gene is sought when there is a known risk of transmission. This group includes pathologies such as cystic fibrosis, Huntington’s disease, sickle cell anemia, various forms of thalassemia, and some muscular dystrophies, among others. The analysis is specifically designed to detect that particular genetic alteration.
This method increases the chances, but does not completely eliminate the uncertainty inherent in any biological process.
Among its main advantages is the increased probability of achieving a successful pregnancy in fewer attempts. Selecting embryos with better genetic viability reduces unsuccessful transfers and, in many cases, also the risk of miscarriage related to chromosomal abnormalities. This not only improves medical care but also reduces the time involved and lessens the physical and emotional strain. Each transplant requires significant coordination, medical preparation, and emotional commitment from both the intended parents and the surrogate.
Having a tool that reduces risks and increases the chances of success provides greater peace of mind and security for everyone involved. However, there are also limitations that are best understood clearly. Preimplantation genetic diagnosis does not identify all diseases that could be genetic, but only those included in the specific analysis performed. Furthermore, it can only be performed during an in vitro fertilization cycle, meaning that this process must be undergone even when, under other circumstances, it might not be necessary.
On the other hand, it represents an additional cost to the overall treatment, and sometimes the embryos examined may not be genetically viable for transfer. While informative from a medical standpoint, this situation can be emotionally challenging.
Understanding both the advantages and limitations facilitates more informed and realistic decision-making. Assisted reproduction is not about seeking absolute guarantees, but about minimizing risks, maximizing opportunities, and progressing with the best possible information.
How much does preimplantation genetic diagnosis cost?
The cost of preimplantation genetic diagnosis can vary considerably depending on the country where the treatment is performed, the chosen clinic, and the type of test indicated. In most cases, it is an additional cost to the in vitro fertilization cycle, as it involves specialized procedures and analyses that require advanced technology and specific laboratories.
The final price usually depends on several factors. One of these is the number of embryos to be analyzed, as each sample requires individualized study. The type of test performed also influences the price: a PGT-A test, used to analyze numerical chromosomal abnormalities, is not the same as a PGT-M test, designed to detect a specific genetic mutation in a particular family, or a PGT-SR test in cases of structural chromosomal abnormalities. The complexity of the clinical case and the country where the treatment is performed can also significantly affect the cost.
You can read other articles of interest at:
- A groundbreaking question about the PGTA test.
- The PGTA test in surrogacy reveals the embryo’s genetics and improves embryo transfer.
- Is it possible to select the baby’s sex in surrogacy using the PGTA test?
In international surrogacy programs, preimplantation genetic diagnosis is usually included in the overall budget, especially when it’s part of the recommended medical protocol. This allows the cost to be integrated into the overall planning and avoids unexpected costs later on.
In any case, beyond the price, the truly important question is not how much it costs, but whether it is medically indicated and whether it can provide a real benefit in that specific case. The decision should be based on clinical criteria and a personalized assessment, not solely on an economic calculation.
An informed decision is a more peaceful decision.
Preimplantation genetic testing (PGT) is not a required or mandatory test in all assisted reproduction procedures. Each case is unique and must be analyzed individually. However, when there is a specific medical indication, it can be very important in terms of the safety and effectiveness of the procedure, and especially for peace of mind.
It is essential to understand that it is not about “perfecting” embryos or seeking unrealistic standards. The goal is to reduce known risks, prevent problems related to genetic disorders, and increase the chances of a successful pregnancy from the start.
Having access to accurate, evidence-based information is essential in the context of surrogacy, where each phase requires meticulous planning, coordination among professionals, and a strong emotional commitment from everyone involved. While data-driven decisions don’t completely eliminate uncertainty, they do allow you to face it with greater confidence.
Now that you know what preimplantation genetic testing (PGT) is, how it works, and in what circumstances it’s typically recommended, the most relevant question isn’t whether this technology is available. The real question is whether, in your specific situation, it can provide genuine value and help you move forward with greater confidence in your reproductive journey.
FAQs about preimplantation genetic diagnosis
- What does a PGD detect?
It detects alterations in the number or structure of chromosomes and specific genetic mutations previously identified in the parents. - Preimplantation genetic diagnosis performed?
Blastocyst — stage embryo during an in vitro fertilization cycle. A few cells are extracted and genetically analyzed in the laboratory, while the embryo remains frozen until the results are obtained. - When is PGD recommended?
It is recommended in cases of advanced maternal age, recurrent miscarriages, implantation failures, family history of genetic diseases, or when one of the parents is a carrier of a genetic alteration. - When is a PGD necessary?
It is necessary when there is a known risk of transmitting a genetic disease, when there is a history of repeated pregnancy losses, or when the aim is to optimize the chances of success in complex treatments such as surrogacy. - What is preimplantation genetic diagnosis?
It is a genetic analysis technique of embryos obtained by IVF before their transfer to the uterus, in order to detect chromosomal abnormalities or hereditary diseases. - What diseases are detected with preimplantation genetic testing?
It can detect chromosomal abnormalities such as trisomies and specific monogenic diseases such as cystic fibrosis, Huntington’s disease, thalassemias or muscular dystrophies, depending on the type of study performed. - How much does preimplantation genetic diagnosis cost?
The price varies depending on the country and the type of test, but it is usually an additional cost to the IVF treatment. In surrogacy programs, it is typically included in the overall cost of the process.
