Preimplantation genetic diagnosis.

Preimplantation genetic diagnosis (PGD) involves testing for specific genetic conditions prior to the implantation [5] of an embryo in the uterine wall. This form of genetic screening has been made possible by the growth of in-vitro fertilization [6] (IVF) technology, which allows for the early stages of development to occur in a laboratory dish rather than in vivo [7]. The purpose of PGD is to identify what are considered to be abnormal embryos in order to select the most desirable embryos for implantation [5]. Diagnosis is comprised of two steps: extraction of one or two cells from an IVF-produced embryo, and application of the PGD test. PGD is important to embryology [8] because it has advanced IVF results and allowed couples more opportunities to deliver a child to term; however, it has also created much controversy.