ABSTRACT

THE CHALLENGES OF VITRIFICATION AND IN VITRO FERTILIZATION (IVF) AUTOMATION e cryopreservation of embryos during assisted reproduction technologies (ARTs) is an essential practice for clinics to maximize cumulative pregnancy rates. e most eective method of cryopreserving embryos is vitrication, which typically uses high concentrations of cryoprotectants and ultra-rapid cooling to preserve cells in a glass-like (vitreous) state without detrimental ice crystal formation.1 When successfully executed, vitrication produces extremely high embryo recovery rates, in excess of 90%, and pregnancy, live birth, and neonatal outcomes equivalent to (or better than) those from fresh transfers.2-4 However, vitrication is a manual, time-consuming, and high-skill procedure, and outcomes can vary greatly between operators and ART clinics.5 Multiple vitrication devices and protocols are currently in use, which vary greatly in the constitution of cryoprotectants and conditions of embryo exposure, the rate of cooling and subsequent warming, and whether or not the embryo comes into direct contact with liquid nitrogen.6,7 e numerous vitrication variables involved, including actual temperatures during the process, the exact duration of embryo exposure to solutions, and the diusion gradient of solutions at the embryo level, make it very dicult to standardize the procedure when performed manually.