PGD is a technique used in In Vitro Fertilization (IVF) which allows genetic evaluation of an embryo before transfer and subsequent implantation (hence the term, "preimplantation" genetic diagnosis). This technique involves the removal of a single cell from a 6-8 cell embryo, usually 3 days following egg retrieval. The cell is fixed and can be analyzed for genetic abnormalities. The embryos are allowed to grow to blastocyst (more advanced stage) and "normal" embryos are then transferred on day 5-6. Common indications for PGD include carriers of single-gene disorders such a cystic fibrosis, patients with a family or personal history of inheritable disorder, and carriers of abnormal chromosomes. HLA matching is another potential use for this technology. The use of PGD for recurrent pregnancy loss (RPL), increased reproductive age of the female partner, or repeated implantation failure (i.e. multiple failed IVF cycles) has not been established.
Limitations of this technology are listed below:
 Requires adequate numbers of embryos to allow blast transfer
Often, no additional embryos for freezing
Risk of no embryos for transfer
Misdiagnosis
Low risk of damage to the embryo during biopsy
 
Embryo Biopsy Blastocyst
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