#386 : Warming Vitrified Oocytes in a Fraction of the Current Required Time Results in Superior Survival Rates

Abstract

Background and Aims: Oocyte vitrification and warming is very time consuming. Oocyte vitrification protocols are different from that of embryos or blastocysts, while warming protocols allow all to be warmed the same. For blastocysts, frequently only one device is warmed per patient; however, numerous devices are required in oocyte warming. We aim to evaluate whether vitrified oocytes can successfully survive a warming protocol involving only Thawing Solution (TS) with a total elapsed warming time of a mere 90 seconds. Methods: 58 vitrified donor oocytes (Treatment Group) were prospectively warmed in January 2023. 71 vitrified donor oocytes (Control Group) warmed in 2022 were retrospectively analyzed. Both groups were vitrified in Kitazato or Irvine Scientific Vit Kit with identical protocols (elapsed time approximately 17-minutes). In both groups the TS was equilibrated to 37-degrees for a minimum of 2-hours. The Control Group was warmed in Irvine Scientific Vit Kit (1-minute TS, 3-minute DS, 8-minute WS) for a total warming time of 12-minutes. Warming for the Treatment Group was in Irvine Scientific Vit Kit Warm-NX, TS only, for 90-seconds. Results: After Chi-square analysis, [Formula: see text] value < 0.05 reflected significance. The Control Group warmed with 90.1% survival. The Treatment Group resulted in 98.3% survival, ([Formula: see text] -value = 0.056). Survival at 3-hours post warm in the Control Group was 100%. At this point for the Control Group, ICSI was performed, and the oocytes placed back into the incubator for resulting embryo culture. For the Treatment Group, oocyte survival was re-assessed at 1-hour and 24-hours, and 100% survival was maintained over the course of 24-hour incubation, with little-to-no visible cryo-damage. Conclusions: Vitrified oocytes exhibit outstanding survival when warmed with a highly modified and considerably faster protocol than current practice. The extended oocyte survival of at least 24-hours shows a very favorable outcome for the accelerated warming protocol and gives credibility to the survival assessment.