Dr. Victoria Verdú Merino explains that Preimplantational Diagnosis (PGD) is a method of Prenatal Diagnosis that aims to increase the probability that children will be born genetically healthy and, therefore, will not suffer from chromosomal syndromes or hereditary pathologies. PGD allows us to genetically examine the embryos obtained through in vitro fertilization and to detect chromosomal or genetic abnormalities before transferring the embryos to the woman.
For which patients is this treatment indicated?
Specialists recommend this treatment in the case of couples who suffer from or are carriers of genetic or chromosomal diseases that can be transmitted to their offspring. In addition, it is recommended for women of advanced age, for women who suffer repeated miscarriages and for patients who have already undergone several unsuccessful IVF cycles.
What does the procedure consist of?
The technique consists of extracting a group of cells from each embryo by means of an embryo biopsy. Once the biopsy has been performed, the embryo is put back into the laboratory incubator and kept in in vitro culture with the appropriate environmental conditions so that it can continue its normal development until the moment of transfer to the patient’s uterus. An embryonic freezing or vitrification process can also be performed until the genetic results of each embryo are obtained.
The cells obtained from the biopsy are genetically examined in order to check if the embryo suffers from any chromosomal or genetic alteration. The remaining cells of the embryo are usually genetically identical to the biopsied cell and continue their development in incubators. Once the genetic result of the embryos has been obtained, they are transferred to the mother’s uterus in the best possible conditions, normally in a subsequent cycle of the patient.
What are the benefits of this process?
There are several benefits to this process. The first is that it makes it possible to detect genetic anomalies in the embryos, so that in patients with embryo implantation failure or repeated miscarriages, by selecting genetically healthy embryos, pregnancy rates increase, reducing the possibilities of miscarriage and shortening treatment times in patients. This is especially beneficial for women of advanced maternal age, in whom the passage of time is crucial for the possibility of having a child. On the other hand, in patients who are carriers of rare diseases that can be transmitted to their children, there is hope of having healthy children.
Are there any risks?
The risks of performing a treatment with preimplantation genetic diagnosis are the same as those of performing an in vitro fertilization cycle: there may be complications in relation to ovarian stimulation, ovarian puncture for the extraction of the oocytes… but the risks are minimal and are very well controlled. The medication protocols used at this time minimize the risks of ovarian hyperstimulation, and the current trend of transferring embryos one at a time has greatly reduced the rates of multiple gestation. There are many advantages that this technique offers us, while minimizing the risks involved.