Preimplantation Genetic Diagnosis (PGD) is a new method of prenatal diagnosis that is developing from a union of IVF technology and molecular biology. Briefly stated, PGD involves the creation of several embryos in vitro from the eggs and sperm of an interested couple. The embryos are permitted to develop till 6 to 10 cell stage, at which point one of the embryonic cells is removed from each embryo and the cellular DNA is analysed for chromosomal abnormalities or genetic mutations either by polymerase chain reaction [PCR] or Fluorescence Insitu Hybridization [FISH].
An embryo or embryos found to be free of genetic abnormalities are subsequently transferred to the woman’s uterus.
In certain situation in which the genetic problem is only with the female, a polar body can be removed from the eggs and tested before fertilization.