Shortened vitrification and warming improve survival and accelerate meiotic resumption in human germinal vesicle oocytes compared with standard protocols.

purposeDo shortened vitrification and warming (S-V/W) protocols achieve similar survival rates and meiotic resumption compared with standard protocols in human germinal vesicle (GV) oocytes?

methodsA prospective sibling study was conducted with 230 vitrified human GV-oocytes obtained from 43 patients. Oocytes were divided into three groups: standard vitrification and warming protocols (STD-V/W), S-V/W protocols, and fresh control. Survival rates were assessed at 2 and 24 h post-warming. GV breakdown (GVBD, GV to MI) and maturation rates were assessed at 2, 4, 6, 24, and 48 h post-warming. An analytical model was developed to estimate laboratory workload associated with oocyte vitrification and warming under routine clinical conditions.

resultsThe S-V/W group showed higher survival rates compared with the STD-V/W group at 2 h [STD-V/W: 76/95 (80.0%) vs S-V/W: 90/98 (91.83%), p-value = 0.02] and 24 h [STD-V/W: 74/95 (77.89%) vs S-V/W: 88/98 (89.79%), p-value = 0.03]. The S-V/W group showed faster meiotic resumption, with a significantly higher GVBD rate at 2, and 6 h (p-value = 0.001 and p-value = 0.003, respectively), as well as earlier (6 h, p-value = 0.005) and increased MII appearance at 24 h (p-value = 0.010). The shortened protocol achieved an adjusted workload reduction of ~ 60-75% for vitrification and ~ 75-85% for warming.

conclusionsThis study highlights the advantages of the S-V/W protocols in improving survival rate, laboratory workflow, and accelerating meiotic resumption and MII appearance. In conclusion, these findings are promising and primarily support the need for further investigations in human mature oocytes.