Preimplantation genetic diagnosis presents a highly specialized technique designed to identify chromosomal aberrations (deviations, changes) or monogenic hereditary diseases before the embryo transfer into the uterus. The studies of chromosomal structures in embryos revealed that the incidence of aneuploidies (deviations in chromosome number) is one of the most common causes for infertility. The examination of embryonal chromosomes may therefore increase the success of IVF. The aim of preimplantation genetic diagnosis is to select only those embryos for the embryo transfer, where PGD found no monitored abnormality.
The indications for the preimplantation genetic diagnosis are especially:
Preimplantation genetic diagnosis is carried out in early stages of embryonic development. After mechanical opening of the zona pellucida, a single cell (blastomere) is collected from the embryo, which is further examined using the methods below. Embryo biopsy – a single cell collection – is usually performed on the 3rd day after the fertilization, when the embryo has 6-8 cells. Only those embryos that are healthy according to the preimplantation genetic diagnosis are then selected for the embryo transfer into the uterus.