Embryo aneuploidy and the role of morphological and genetic screening.

Chromosome abnormalities are common among human oocytes and are usually lethal to any embryos they produce. It therefore seems logical that a reliable technique for distinguishing between normal and aneuploid embryos would be a useful tool for physicians and embryologists, assisting the choice of which embryo(s) to prioritize for uterine transfer. This concept has led to the development of a variety of methods for the detection of chromosome abnormalities in oocytes and embryos, most often referred to as preimplantation genetic screening (PGS). However, several well-controlled studies have been unable to show an advantage of chromosome screening in terms of pregnancy and birth rates. Some investigators have suggested that damage to embryos, sustained during cleavage-stage biopsy, might explain why PGS has not always provided the anticipated benefits. This paper asks whether there is evidence that a non-invasive, morphological analysis could allow chromosomally normal embryos to be accurately identified and reviews data from the most recent publication concerning IVF outcome following PGS.