Assessment of embryo morphology and developmental dynamics by time-lapse microscopy: is there a relation to implantation and ploidy?

Time-lapse microscopy (TLM) is an exciting novel technology with great potential for enhancing embryo selection in the embryology laboratory. This non-invasive objective assessment of embryos has provided a new tool for predicting embryo development and implantation potential. TLM detects several morphological phenomena that are often missed with static observations using conventional incubators, such as irregular divisions, blastocyst collapse and re-expansion, timing of blastocoel appearance, and timing of formation and internalization of fragments. Nevertheless, it should be recognized that conventional morphological assessment has been widely accepted as the gold standard by most embryologists. TLM can enhance conventional morphological assessments to improve embryo selection and subsequent reproductive outcomes. Furthermore, morphokinetic parameters can aid in differentiating between euploid and aneuploid embryos, although they are not sufficiently accurate to replace preimplantation genetic testing for aneuploidy. Morphokinetic assessment together with chromosomal screening may ultimately help identify euploid embryos with the highest developmental potential.