Pre-implantation Genetic Diagnosis (PGD)

Pre-implantation Genetic Diagnosis (PGD) is recommended in patients with multiple IVF failure, advanced maternal age, or if there a family history of chromosomal abnormalities.

To prepare a specimen for analysis of genetic diseases, an opening is made in the covering of an embryo during its third day of development when the embryo has 8-10 cells. A blastomere, a cell from an embryo, is removed via aspiration with a pipette and placed on a microscope glass slide for transport to the laboratory for analysis.  This process is called embryo biopsy and fixation.  The embryo is placed in an incubator while the biopsied cell(s) are sent for analysis.

PGD is the testing of a cell from an embryo prior to transfer of the embryo to the uterus.  The biopsied cells are analyzed using a technique called fluorescence in-situ hybridization or FISH. This technique uses probes, small pieces of DNA that are a match for the chromosomes we want to analyze, to count the chromosomes present. Each probe is labeled with a different fluorescent dye. These fluorescent probes are applied to the biopsied cell and attach to the chromosomes. Under a fluorescent microscope, we then count the number of chromosomes of each type (color) there are in that cell. The geneticist therefore can distinguish normal cells from cells with abnormalities.