Answer from: Raúl Olivares, MD
For a standard PGS or PGT-A, in both cases, the test is the same. What is usually done is that on day 5, we are taking some cells from the trophectoderm of the embryo. Those are the cells that are going to become a placenta later on. Once we do the biopsy, we freeze the embryo, we take those 3-5 cells to the lab. Then, usually, we need 2 weeks to get the results and confirm whether that embryo is genetically normal or not.
When we do PGS/ PGT-A, what we are going to do first is, stimulate the patient, get the eggs, create the embryos and do the biopsy, keep them frozen for 2 weeks. As soon as we get the results, if there is any embryo suitable for the transfer, we are going to prepare the patient for that frozen embryo transfer.
Answer from: Elisa Moya Gutiérrez
PGT-A is a genetic test performed on embryos that have been created through an IVF cycle. PGT- A detects abnormalities in the number of chromosomes in the embryos, also known as aneuploidies. Chromosomes are very important for healthy growth and development. Embryos with the incorrect number of chromosomes typically do not result in a successful pregnancy. They may also lead to the birth of a child with a genetic condition.
PGT-A identifies embryos with the correct number of chromosomes, so our team can select the best embryo with the best chance of success in an IVF cycle. To do the PGT-A, first, we need to create the embryos through an IVF cycle. When these embryos are created, we have embryonic development until day-3 or day-5 of culture, it always depends on the case. Once we decide how long we’re going to leave the embryos in culture, we have the embryo biopsy. A few cells are removed carefully from the embryo from the part of the embryo that will form the placenta. Samples are sent to a genetic laboratory while the embryos remain safe in culture, or in some cases, we can freeze them.
In the genetic laboratory, they have other technologies to analyse the genetic material present in every embryo, and we can obtain the results only in 24 hours if you want to do a fresh embryo transfer. If not, then the results can last for one week. Embryos that we are going to transfer are always the ones that have no abnormalities. These are the ones that have more chances to succeed in pregnancy. If we have more than 1 or 2 embryos that have no abnormalities or aneuploidies, we can freeze these embryos for future use.
Many people wonder if PGT-A is a trustful test. The accuracy of PGT-A is around 98%. With this data, we can confirm that the results of this test are reliable. Another doubt that is very common in our patients is if the biopsy can damage the embryos. As with any manipulation process, a possible risk of damage cannot be completely denied.
However, if the biopsy is performed by an expert and if the embryos are of good quality, there shouldn’t be any risk at all. Several studies have shown that embryo biopsy does not affect embryonic development and subsequent implantation. PGT-A will always be recommended in our clinic as long as there is a medical indication.
What is the timeframe for the PGS/ PGT-A test?
PGT-A (Preimplantation Genetic Testing for Aneuploidy), also known as PGS, is a helpful technique for many couples undergoing IVF. There is always a risk of chromosome abnormality, but the question is – what exactly does PGT-A/PGS test for in IVF? Is it always recommended by the doctor? When should it be performed? How much time does it take to do PGT-A?