Pre-implantation genetic testing (PGT) – pre-implantation diagnosis

Statistics show that in almost 80% cases, a healthy pregnancy depends on a healthy embryo; this is why pre-implantation genetic testing (PGT) represents a real breakthrough for couples undergoing IVF treatment. Thanks to this, we can analyse embryos precisely even before they are transferred to the uterus. This allows us to select those with the greatest developmental potential and which are free from serious genetic defects. In this way, we significantly increase the chances of success for IVF treatment, reduce the risk of miscarriage and of a child being born with a serious genetic condition, and, as a result, shorten the path to the parenthood you long for.

What is pre-implantation genetic testing?

Pre-implantation genetic testing (PGT) is carried out as part of the in vitro fertilisation procedure and enables the genetic material of the embryo to be assessed before it is transferred to the uterus. Its aim is to detect genetic abnormalities that may lead to abnormal embryo development, failure to implant, miscarriage or the occurrence of severe genetic defects in the child. 

Pre-implantation diagnosis checks: 

• abnormalities in the number of chromosomes in the embryo (PGT-A, Embrace), 
• chromosomal structural abnormalities (PGT-SR), 
• the risk of a child developing a specific genetic condition that runs in the family (PGT-M).

Any of these abnormalities may lead to a failure of implantation, an early miscarriage following implantation, or cause severe birth defects in the baby. 

Genetic testing of embryos increases the chances of a healthy pregnancy, particularly in difficult cases of infertility and in cases of recurrent miscarriages. It also improves the parents’ peace of mind. 

„The journey to pregnancy isn’t always straightforward. Sometimes it’s like a journey with many stops, twists and turns, and dead ends. Pre-implantation diagnosis is like a map that allows us to see the route in advance – before we set off.” – he says Dr Marta Bogucka, DVM – Head of the embryology laboratory.

„Thanks to this study:

• we avoid paths that lead nowhere, thereby reducing the risk of failure,
• we choose the shortest route, minimising the number of attempts and procedures,
• We can see which routes are safe by assessing the genetic risk before we set off.

”Pre-implantation diagnosis is not a shortcut. It is simply a more sensible way of achieving the goal of a healthy pregnancy." – adds Dr Bogucka.

When is genetic testing carried out on an embryo?

Couples planning a pregnancy – particularly Invimed patients who have been trying for a baby for some time – often undergo a series of laboratory tests to confirm or rule out, amongst other things, the presence of congenital disorders and genetic abnormalities. The diagnostic process involves, amongst other things, genetic tests such as karyotyping, Adventia and others. 

It should be borne in mind, however, that in some cases, genetic defects only become apparent in the offspring. Changes in genetic material can lead to the development of birth defects, most of which can result in foetal death (so-called lethal defects). In such cases, pre-implantation diagnosis is of particular importance. 

Pre-implantation diagnosis can help pave the way to a healthy, dream pregnancy.  

Genetic testing of embryos versus antenatal testing

The key difference lies in when the tests are carried out. Genetic testing of embryos is carried out before pregnancy, during the in vitro fertilisation process. Prenatal testing, on the other hand, is carried out once pregnancy has been achieved. Pre-implantation testing helps to select the embryo with the best chance of a healthy pregnancy, whilst prenatal testing is used to assess the developing baby. Both types of testing serve different purposes and are not mutually exclusive. On the contrary, it is recommended that prenatal testing be carried out even after receiving a normal result from the embryo’s genetic testing.  

How is genetic testing of an embryo carried out?

Genetic testing is carried out during the in vitro procedure: on days 5 and 6, and in justified cases even on day 7 after fertilisation. Once the embryo reaches the blastocyst stage, an experienced embryologist removes a sample of the trophectoderm using a biopsy pipette. The sample, once properly preserved, is then sent to the genetics laboratory, where the genetic material is analysed.

Following the biopsy procedure, the embryos are safely stored (vitrified) until the results of the genetic testing are received. Once the results are received, the healthy embryos are thawed and can be transferred to the patient’s uterus.

In the case of PGT-M testing, a case study is required before stimulation begins. Find out more >>>

As we do not carry out biopsies as part of the Embrace test, the procedure for collecting the sample for testing is carried out in a different way. Find out more >>>

Types of genetic testing on embryos

PGT-A

PGT-A+ is a state-of-the-art genetic test carried out on embryos prior to transfer as part of an in vitro fertilisation procedure. The test detects chromosomal abnormalities (aneuploidies) which may be the cause of implantation failure, miscarriages and genetic disorders such as Down’s syndrome, Edwards’ syndrome, Patau’s syndrome or Turner’s syndrome.

Thanks to the use of advanced technologies, it is possible to select embryos with normal developmental potential and increase the chances of a successful treatment. The combination of advanced genetic diagnostics and rigorous quality control enables the selection of the embryo with the greatest developmental potential, thereby increasing the chances of a successful treatment and shortening the path to a healthy pregnancy for patients.

Find out more >>>

PGT-M

PGT-M is a specialised genetic test carried out on embryos prior to transfer during in vitro fertilisation, which enables the detection of specific monogenic disorders inherited from the parents. The test analyses the embryo’s DNA for mutations responsible for conditions such as cystic fibrosis, Huntington’s disease, phenylketonuria, haemophilia and fragile X syndrome. Thanks to PGT-M, it is possible to select embryos free from a detected genetic condition present in the family, which helps to reduce the risk of passing it on to a child and supports informed family planning.

Find out more >>>.

PGT-SR

Diagnostic testing intended for patients who are carriers of structural chromosomal abnormalities, such as translocations and inversions. Although people who carry such abnormalities often have no health symptoms, they may have difficulty conceiving or maintaining a pregnancy and face a higher risk of passing on genetic abnormalities to their offspring.

PGT-SR makes it possible to identify embryos with a normal chromosome set and select those most likely to develop normally.

Embrace

Invimed was the first infertility clinic in Poland to introduce the non-invasive, preimplantation genetic embryo test Embrace, which makes it possible to check for numerical chromosome abnormalities (aneuploidy). This test promotes safer and more effective IVF treatments and avoids embryo biopsies. This method classifies embryos according to their chance of implantation. Normal embryos of the best quality receive the highest priority for transfer.

Find out more >>>.

Who is genetic testing of embryos intended for?

Genetic testing of embryos is carried out as part of the in vitro procedure.

It is worth having this test done when:

• the patient is over 35 years of age,

• there are recurrent miscarriages or implantation failures,

• the couple have a child with a genetic condition,

• genetic abnormalities have been detected in one or both parents, or possibly among other family members,

• there is a strong male factor,

• Other indications emerged during the medical interview.

PGT-A, PGT-M and PGT-SR tests comply with the Act on the Treatment of Infertility and the recommendations of the Polish Society for Reproductive Medicine and Endocrinology (PTMRiE), and are approved by the Ministry of Health.

Is the test safe?

It should be emphasised that the collection of a sample from the embryo – the trophectoderm – is one of the most difficult procedures in an in vitro laboratory; however, with today’s advanced embryological techniques, the risk of damaging the blastocyst during the biopsy is minimal.

An alternative to PGT-A is the Embrace test. In this test, we do not perform an embryo biopsy; instead, we analyse the embryo’s cell-free DNA from the fluid in which it developed.

How long does it take to get the result?

The waiting time depends on the type of test and can range from 2 to 6 weeks. Exact dates are confirmed with patients on a case-by-case basis before the test is carried out.

Genetic testing of embryos at Invimed

The first genetic testing of embryos at Invimed was carried out in 2003. Since then, we have been constantly expanding our range of services, training our embryologists and collaborating with one of the world’s largest genetic laboratories.

Invimed offers a full range of pre-implantation tests: PGT-A, PGT-M, PGT-SR and Embrace. Diagnostics are carried out in collaboration with doctors, geneticists and embryologists, ensuring comprehensive care at every stage of treatment.

Frequently asked questions

Bibliography

1. Good practice recommendations from the European Society of Human Reproduction and Embryology for pre-implantation genetic testing (PGT)
2. R. Kurzawa, R. Spaczyński, „Diagnosis and treatment of infertility. Standards of the Polish Society for Reproductive Medicine and Embryology and the Polish Society of Gynaecologists and Obstetricians.”