Abstract
Elective single embryo transfer (eSET) is becoming increasingly popular in assisted reproductive technology (ART) in order to avoid multiple pregnancies without decreasing the overall pregnancy rate. It is required to strictly select an embryo with the highest implantation potential for the success of eSET. For selection of the best embryo, it is necessary to introduce several scoring systems in combination, such as presence of multinuclearity in blastomeres, evenness of pronuclear size, early cleavage, various oocytoplasmic anomalies, etc. This enables us to rank each embryo in higher developmental competence order. In this review, we analyze the clinical data, retrospectively, in order to inspect the significance of several morphological markers. In addition to the morphological parameters, several non-invasive molecular or genetic markers (such as levels of embryonic soluble HLA-G, platelet-activating factor or total antioxidant capacity in culture media, apoptosis or microarray analysis of follicular cells or cumulus cells, etc.) have been reported as useful indicators of embryo quality. Compared with the morphological parameters, these cellular and molecular predictors of embryo quality may prove to be more precise and objective. By means of analyzing the significance of each indicator, the precision of embryo evaluation will improve as the patient population increases.
