Application of a single "Universal warming protocol" for vitrified donor oocytes: A multicenter study

The objective of the multicenter study is to demonstrate the efficacy of the "Universal Warming Protocol (UWP)" using different devitrification media in donor oocytes that were previously vitrified in a single egg bank.

A total of 2172 oocytes (metaphase II) were vitrified at Ovobank (Spain) using Kitazato vitrification media (Kitazato, Japan). The oocytes were devitrified at three different centers. Group A: 1021 oocytes devitrified with Kitazato media (Kitazato, Japan); Group B: 496 oocytes devitrified with Irvine media (Fujifilm Irvine Scientific, USA); Group C: 655 oocytes devitrified with RapidWarm Omni media (Vitrolife, Sweden). The study parameters included survival rate, fertilization rate, cleavage rate, blastulation rate, and a pregnancy rate confirmed by a biochemical test; transferring embryos at D + 3 and D + 5; and clinical pregnancy rate, transferring embryos at D + 3 and D + 5.

The survival rate was statistically higher in Group C (94%) compared to Group A (86%) and Group B (85%) (P value < 0.01). There were no statistically significant differences in the remaining parameters: fertilization rate (A: 77%, B: 74%, C: 73%); cleavage rate (A: 83%, B: 83%, C: 80%); blastulation rate (A: 52%, B: 58%, C: 57%); a pregnancy rate confirmed by a biochemical test in transferring embryos at D + 3 (A: 38%, B: 33%, C: 33%); a pregnancy rate confirmed by a biochemical test in transferring embryos at D + 5 (A: 54%, B: 76%, C: 65%); clinical pregnancy rate in transferring embryos at D + 3 (A: 27%, B: 13%, C: 18%); clinical pregnancy rate in transferring embryos at D + 5 (A: 39%, B: 57%, C: 60%).

The idea that oocyte devitrification medium should always be from the same supplier is questionable. Therefore, it is feasible to use different devitrification media for donor oocytes that were vitrified with the same vitrification medium.