Answer from: Raúl Olivares, MD
When we do a PGS, what we are going to do is we are going to take some cells from the embryo. We usually make a hole in the external wall of the embryo, we take 3 to 5 cells from the trophectoderm, which is the structure that is going to become the placenta. Once we do that, we send the cells to the lab, they analyse and check whether these cells have normal or abnormal chromosomes.
In normal circumstances, it takes two weeks to get the results. Once we know if these embryos are genetically normal, then the only thing that we must do is prepare the patient for receiving the embryos. This is done, as any other frozen embryo transfer. It can be done using hormone replacement therapy or using a natural cycle if the patient has a natural cycle. Once the patient is prepared for that embryo transfer, we add the progesterone, and on day 5 of progesterone, we thaw the embryo, and it is transferred.
Basically, it works as a frozen embryo transfer. The only difference is that we first do the biopsy and confirm that those embryos are genetically normal.
Answer from: Maria José Mendiola, MD, MSc in Human Genetics, MSc in Science Communication, ObGyn
Answer from: Dimitra Christopikou, Clinical Laboratory Geneticist
After you get your results you need to speak with a genetic counsellor as they will tell you what the report really says. These counsellors are important specialists that clarify the results. According to the results you may either have a euploid, chromosomally normal embryo or a mosaic embryo to transfer. The counsellor will help you understand what the report says and to help you make a decision if you want to transfer an embryo. Once you have this clarified with the genetic counsellor you have to speak with your doctor in order to arrange the preparation of the endometrium in another cycle to get the transfer. The transfer cannot be carried out anytime during the month; it has to be done on a specific time based on your period.
Answer from: Luca Gianaroli
It depends. If you have normal embryos to be transferred, you proceed to a single embryo transfer. If pregnancy occurs, you can confirm chromosomally normal embryos using non-invasive prenatal testing or other tests during pregnancy.
If pregnancy is not achieved after the transfer of two or three normal embryos, we need to look further at the receptivity of the patient’s uterus, into the capability of the uterus to keep a pregnancy, excluding endometriosis; an inflammatory disease of the endometrium. Also, you have to have a different test that can remove chromosomally normal embryos that have problems from the ones to be transferred.
