What next for preimplantation genetic screening? Randomized clinical trial in assessing PGS: necessary but not sufficient.

The randomized clinical trial (RCT) is a powerful experimental design that when properly executed produces generalizable results. Conducting a RCT becomes complex when technical skills are required. Without requisite skills, a RCT may yield misleading results, an elegant RCT unwittingly generating spurious results due to technical inexperience. This pitfall is applicable to procedures used to evaluate assisted reproductive technologies. RCTs assessing the value of preimplantation genetic screening, also called preimplantation genetic diagnosis for aneuploidy testing--require three general prerequisites--proper study design, skilled operators (embryo biopsy), and skilled laboratory cytogeneticists (diagnosis). Lacking either of the latter two, even an elegantly designed RCT is not necessarily valid.