Non-Invasive Assessment of Viability in Human Embryos Fertilized in Vitro.

Human reproduction is a relatively inefficient process and therefore the number of infertile couples is high. Assisted reproductive technologies (ART) have facilitated the birth of over five million children worldwide. ART, however, superimposes its own relative inefficiency on the preexisting inefficiency of normal reproduction. The efficiency (expressed as pregnancy rate) is generally not more than 30%. Modern reproductive medicine is gradually moving from multiple embryo transfer to the transfer of a single embryo, mainly because of obvious and unwanted side effects of multiple embryo transfer (e.g. "epidemic" multiple pregnancies). This concept, however, requires a fast, professional selection of the most viable embryo during the first few days of ART. Thus the aim of a modern ART is the safe transfer of a healthy, viable, single embryo. Accurate and rapid methods of quantifying embryo viability are needed to reach this goal. Methodological advances have the potential to make an important contribution, and there has been a drive to develop alternative non-invasive methods to better meet clinical needs. Metabolic and genetic profiling of spent embryo culture (SEC) media should offer an exceptional opportunity for the assessment of embryo viability. The current review focuses on the latest non-invasive diagnostic approaches for pre-implantation viability assessment of in vitro fertilized embryos.