Preimplantation genetic diagnosis (PGD), which is carried out within the programs of IVF or IVF/ICSI, is a way of detection of genetic anomalies of an embryo before its transfer to the uterine cavity. This test allows to prevent the transmission of some hereditary diseases to a future child.
Preimplantation genetic diagnosis (which is sometimes called the embryo screening) is intended not only for the couples who have the infertility problem, but also in the cases when there is no infertility. If a woman can experience the habitual noncarrying of pregnancy or the couple has any genetic disorders, the doctors of the clinic recommend the PGD procedure, in the process of which they will select only the healthy embryos to be transferred into the uterine cavity.
On the 3rd day after the fertilization, one or two cells – blastomeres – are extracted from each 6-to-8-cell embryo with the help of special micromanipulators. These cells contain chromosomes which are analyzed for certain anomalies. The PGD procedure doesn’t harm the embryo, it continues to develop after the extraction of a cell. In order to carry out the preimplantation genetic diagnosis, the FISH analysis (fluorescent in situ hybridization), PCR analysis (polymerase chain reaction) or CGH analysis (comparative genomic hybridizations) are usually used. The geneticist doctor chooses the method for the PGD procedure in each specific case.
Preimplantation genetic diagnosis is the only way to detect chromosome diseases in the embryos. Not only it allows to prevent the birth of a child with chromosome diseases, but it also increases the efficiency of in vitro fertilization and decreases the likelihood of miscarriage. In addition, this method allows to detect the gender of a future child.