VALIDATION OF A NEW, ULTRA-FAST BLASTOCYST WARMING TECHNIQUE REDUCES WARMING TIMES TO 1 MIN AND YIELDS SIMILAR SURVIVAL AND RE-EXPANSION COMPARED TO BLASTOCYSTS WARMED USING A STANDARD METHOD.

Embryo warming is an essential practice in IVF. During warming, a blastocyst is moved through a series of solutions to remove the cryopreservation agent. This technique has demonstrated high survival and implantation rates, but also requires approximately 10-15 minutes of bench time for the embryologist. This study introduces a new approach to embryo warming, deemed ultra-fast warming, which only involves warming blastocysts in thawing solution (TS) at 37°C for 1 minute before placing them in culture media. This method would eliminate the need for a dilution and warming solution while also decreasing the number of steps and time to complete the warming process. It is the objective of this study to compare initial survival and re-expansion of blastocysts after 24 hours that undergo ultra-fast versus standard warming methods. DESIGN: Prospective Randomized. All blastocysts were warmed using thawing media from Fujifilm. Blastocysts that were frozen on day 5 and donated to research were randomly warmed utilizing either the ultra-fast (1 minute in TS) or standard warming method (1 minute in TS, 4 minutes in dilute solution, and 8 minutes in washing solution). The embryos were evaluated for survival directly after warming and re-expansion after 24 hours. A total of 71 blastocysts were randomized between ultra-fast warming (n=39) and standard warming (n=32). There was no difference in initial survival between ultra-fast and standard warming procedures: 39/39 (100%) and 32/32 (100%; P=NS). After 24 hours in culture, 39 of 39 (100%) of the blastocysts that were warmed using the ultra-fast method were re-expanded, while 31 of 32 (96.9%) of the blastocysts that were warmed using the standard method were re-expanded (P=NS). Our data suggest that there are no significant differences in the initial survival and re-expansion (after 24 hours) of embryos that were warmed utilizing the ultra-fast compared to the standard warming methods.