PGT-A: aneuploidy

Pre-implantation genetic testing of aneuploidies (PGT-A), previously pre-implantation genetic screening (PGS), is performed during IVF treatment and makes it possible to select a prospective embryo with a normal number of chromosomes for insertion into the uterus. Such an embryo has the highest chance of nesting, without miscarriage, leading to the birth of a healthy child.

Why are chromosomes so important?

Many IVF cycles end up in disappointment due to the failure of embryonic nesting in the mother’s uterus. An incorrect number of embryonic chromosomes transferred to the mother’s uterus may be one of the many causes of an IVF cycle failure. The condition in which the embryo has extra chromosomes, or when some chromosomes are missing, is called aneuploidy.

• Most pregnancies with aneuploid embryos end in a spontaneous miscarriage during the first trimester.
• Certain types of aneuploidy in embryos may result in the birth of a child affected by, e.g. Down syndrome (extra chromosome 21), Edwards syndrome (extra chromosome 18), or Patau syndrome (extra chromosome 13)
• The risk of aneuploidy rises with the increasing age of women. Physicians believe that this is the main reason women experience a steep decline in fertility during the third and early fourth decade of their lives.

Examination of chromosome aneuploidy in embryos prior to their transfer to the mother’s body during IVF allows for the selection of embryos without identifiable genetic abnormalities. The purpose of this test is to increase the chance of giving birth to a healthy child and the success of the IVF cycle.

What is the purpose of chromosome testing?

The purpose of chromosome testing is to facilitate the birth of a healthy child in the shortest possible time horizon and thus, it is the safest treatment.

• Reduce the number of spontaneous miscarriages.
• Reduce the risk of complications during pregnancy.
• Reduce the treatment time and reduce the financial costs associated with the birth of a healthy child by reducing the number of repeated cycles.
• Reduce the number of multiple pregnancies by transferring examined embryos with the highest probability of the birth of a healthy child.
• Provide important diagnostic information to the patient to decide about the next IVF cycle or to request the donation of eggs.

What is the benefit of PGT-A for IVF outcomes?

In a conventional IVF cycle without pre-implantation, the embryos are selected for transfer based on morphological criteria or the dynamics of development. Unfortunately, these criteria are not sufficient to reliably exclude an embryo with a genetic abnormality.

Pre-implantation testing, where we can check the embryo’s genetic make-up and subsequently select a suitable embryo for transfer, will increase the probability of pregnancy, while reducing the risk of miscarriage. Couples with a worse prognosis for the success of the IVF cycle can therefore significantly increase their prognosis using PGT-A to achieve the same good results as those from the group with good prognosis, which represents a success rate of over 40% of pregnancies per transfer, even in the case of the transfer of one embryo.

For whom is pre-implantation testing suitable?

Pre-implantation testing is highly suitable for couples that meet the following indications:

• higher age of the woman
• repeated miscarriages
• repeated unsuccessful embryo transfers in previous IVF cycles
• miscarriage or a foetus with developmental defect (chromosomal abnormality)
• bad parameters of partner’s spermiogram (presence of pathological forms of sperm)
• chromosomal abnormalities detected in the couple
• use of sperm after TESE, MESA
• conditions after treatment of oncological diseases using chemotherapy or irradiation and more …

Pre-implantation testing of aneuploidies significantly increases the success rate of IVF cycles. Hence, all couples can use it, and it’s not limited exclusively to couples with genetic risks.