What are the benefits of Preimplantation Genetic Screening for IVF?
Friday March 16th, 2018
One of the benefits of opting for In Vitro Fertilisation (IVF) is that patients may be tested for potential genetic problems before attempting a cycle. Preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD) are extra stages of the procedure that patients are able to opt for if they are worried that there may be factors that might prevent them from conceiving without complications. This is especially useful for determining whether a couple is liable to pass a genetically inherited abnormality on to their child. It may be recommended for older patients, for those who have suffered multiple unexplained pregnancy losses or for those who have been through multiple failed rounds of IVF. PGS and PGD are additional services which can offer peace of mind to those wanting to rule out problems. Both processes are carried out on fertilised eggs, or “pre-embryos”.
PGS and PGD
There is a slight difference between PGS and PGD: PGS screens for any chromosomal abnormalities that may be present, while PGD looks out for something specific. If one or both of the parents are at risk of a particular chromosomal abnormality, PGD may be the right choice. In 2006, IVI were able to help a couple with a high risk of lymphohistiocytosis to conceive without complications. This was a world first, and since then the procedure has gone from strength to strength. Couples, or even single patients, who have a high risk of chromosomal abnormalities will be identified during their initial consultations, where their medical history will be discussed at length.
PGS on the other hand is a more suitable option for patients who have suffered unexplained miscarriages, or who are over 40 and want to start their cycle of IVF with all the facts at hand. Opting to carry out PGS will mean that the patient or patients are aware of any issues that may prevent them from conceiving without genetic complications, and may even be offered the opportunity to avert them. Only healthy embryos are selected for transfer into the uterus, allowing IVI to perform SET, or single embryo transfer. This also has the advantage of reducing the possibility of multiple pregnancy, which can place unnecessary strain on the female patient’s body.
Which abnormalities can be checked for?
Among the best known chromosomal abnormalities that may be identified by combining PGS and IVF are Down’s syndrome, muscular dystrophy and Huntington’s disease, though this is not a definitive list. Down’s syndrome occurs when the embryo receives three copies of chromosome 21 from the male partner and one copy from the female partner. In much of the developed world it is common to test for Down’s, Edwards’ and Patau’s syndromes in early pregnancy, but PGS gives patients the option of identifying these genetic anomalies much earlier in the process. It is possible to avoid conceiving a child with potentially debilitating genetic diseases by opting for preimplantation genetic screening (PGS) before the embryo is implanted.
Edwards’, Patau’s and other syndromes
Unfortunately, children born with Edwards’ and Patau’s Syndromes often have a short lifespan. Other chromosomal abnormalities such as muscular dystrophy and Huntington’s disease may mean that the child is able to have a mostly normal life until the disease starts to take hold. This does mean that the child will face some sort of medical dependency for most of their life, and can mean that they are limited in what they are able to do as they get older. They may also have to face becoming disabled or even dying very young. While nobody would choose this for their child, PGS and PGD mean that the parents can be informed of any potential issues at a very early stage. As only healthy embryos are transferred, the chances of degenerative disease following conception after PGS are extremely low.
What does PGS entail?
In both PGS and PGD procedures, eggs are harvested from the female patient and fertilised. Otherwise, the IVF procedure is exactly the same as usual. As the testing is carried out on the fertilised egg, neither PGS nor PGD are painful. These “pre-embryos” undergo a biopsy to investigate each chromosomal pair. Over the previous decade preimplantation genetic screening has become increasingly comprehensive, from being able to inspect just 9 chromosomal pairs in 2006 to being able to investigate all 23 pairs in 2018. This means that the procedure is more likely than ever before to yield a result that allows the patients and their medical professionals to make the best possible choices for their situation.
Once PGS has been performed and the results have been disclosed, IVF continues in the usual way. Only the embryo given the all-clear will be placed in the uterus of the female patient and allowed to develop as normal. PGS success rates are higher than when IVF is used alone, with pregnancy rates reaching around 70% as opposed to 50% without PGS. The process allows IVI’s medical professionals to identify and circumvent issues which may otherwise have prevented pregnancy, and greatly improves the odds of a cycle working. This means that the patient will likely only have to go through one cycle of IVF.
Who can opt for PGS?
The first port of call with any fertility treatment through IVI is always a discussion about the medical history and needs of the patient or patients. Whether the patient has been through IVF before with another practitioner or not, IVI’s clinics attach great importance to getting to know the patient’s unique situation and working out what is the best way to move forward. While we do not have a firm upper age limit, the medical community in Spain generally agrees that 50 is a reasonable age to stop providing fertility treatments. Apart from this, the biggest factors in determining whether to go ahead with IVF will be genetic factors, any previous miscarriages and any other particular circumstances. The age of the male patient (if there is one) may also be a concern, as Down’s syndrome and other chromosomal abnormalities are more common in embryos having developed from the sperm of older men.
The likelihood is that if PGS is a suitable choice for the patient or patients, IVI will identify this very quickly. Unlike clinics in other European countries, at IVI the waiting time between opting for IVF and starting treatment is very short to non-existent. PGS is carried out following the egg fertilisation stage of IVF, so it does not add a significant amount of time onto the process at all. Opting to carry out IVF with PGS or PGD at IVI is a great way to save time, which makes it ideal for those who are nervous about long waiting times at other clinics.
Combining donors with PGS
In some cases, PGS and PGD will determine that the best course of action is to opt for donor eggs and/or donor sperm and transfer any resulting screened embryos into the female patient. This may be the best way to conceive without complications. In IVI’s clinics in Spain, access to donated oocytes (eggs) and spermatozoa (sperm) is straightforward and waiting times are short to non-existent. Patients will always be paired with donated material that best matches their own genetic profile, and the donated egg or sperm will also go through PGS. This ensures that conception takes place on a sound basis, and that the female patient has the greatest possible chance of falling pregnant.
IVI will determine the best course of action for each patient individually, from choosing the most appropriate type of fertility treatment to deciding whether PGS or PGD is advisable in conjunction with IVF, to deciding whether to use a donor. Our expertise in the field of fertility means that we are able to confidently guide our patients through the most suitable procedures, something which is reflected in our success rates. By pairing knowledge with ground-breaking new procedures and technology, we continue to improve our pregnancy rates.
Whether this is your first round of IVF or your fifth, IVI’s medical experts are on hand to help you make the right decisions. Opting for IVF Plus, which combines a standard IVF cycle with preimplantation genetic screening or preimplantation genetic diagnosis, will give you the best possible chance of falling pregnant on a sound genetic basis.