A critical appraisal of cryopreservation (slow cooling versus vitrification) of human oocytes and embryos

Abstract

Background: Vitrification is now a commonly applied technique for cryopreservation in assisted reproductive technology (ART) replacing, in many cases, conventional slow cooling methodology. This review examines evidence relevant to comparison of the two approaches applied to human oocytes and embryos at different developmental stages. Methods: Critical review of the published literature using PubMed with particular emphasis on studies which include data on survival and implantation rates, data from fresh control groups and evaluation of the two approaches in a single setting. Results: Slow cooling is associated with lower survival rates and compromised development relative to vitrification w..