Pre-Implantation Genetic Diagnosis (PGD) is a medical procedure performed before the implantation of a fertilized egg during in vitro fertilization (IVF) to diagnose genetic or chromosomal abnormalities in the early stages of embryonic development.
PGD involves the extraction of a single cell from a developing embryo and analyzing it for any genetic or chromosomal anomalies. This process is performed 3-5 days after fertilization when the embryo has reached 8-10 cells. If the results of the test indicate the presence of any abnormalities, the affected embryos are not transferred to the uterus, allowing only healthy embryos to be implanted.