Authors: Lodovico Parmegiani | C. Lynch | A. Arnone | Walter Ciampaglia
Source: Human Reproduction (article, 2025-06-01)
Field: Chemistry — Physical and Theoretical Chemistry

P-128 Universal warming remains efficient with single-step elution warming protocols Abstract Study question Are single-step warming protocols efficient with the practice of universal warming? Summary answer Universal warming remains efficient with single-step warming protocols, in term of embryology and clinical outcomes. What is known already Clinics receive reproductive cells that have been cryopreserved at other facilities using various vitrification protocols/media/cryo-device. Oocytes and embryos are routinely cryopreserved using different commercial brands of ready-to-use vitrification solutions which differ only slightly in their composition. It has previously been demonstrated that the combined use of different vitrification/warming kits is feasible. However, this concept has not been tested in conjunction with single-step warming protocols using only the first elution step with 1M non-permeating solutes (NPS). Study design, size, duration This retrospective observational study was performed on 329 blastocysts vitrified and warmed between 01/01/2024 and 31/12/2024. Blastocysts were vitrified in Kitazato, SAGE, or Irvine media and warmed with warming media from one of the three manufacturers using a single-step protocol. Blastocyst survival (SR), clinical pregnancy (CPR), implantation (IR) and clinical loss (CLR) rates were calculated for all nine combinations of vitrification and warming media. Statistical analysis: Chi Square/Yates and Fisher exact tests. Participants/materials, setting, methods Vitrification and warming were performed using the 9 possible combinations of kits by Irvine-Fujifilm [I], Kitazato [K], and SAGE CooperSurgical [S]. Blastocysts were vitrified using a “universal” protocol performed at room temperature: 12-15min in ES, 50sec in VS, then transferring the embryo to a second drop of VS, loading and plunging within 70sec. Warming was performed using 4 ml of 1M non permeating solute (NPS) at 37 °C. Transfer was performed after 1-2hrs incubation. Main results and the role of chance Group first initials indicate the vitrification media and the second the warming. Survival rate was 100% in all groups. Overall, 329 blastocysts were warmed and transferred in 303 cycles, resulting in a CPR of 45.2%, IR of 42.3% and CLR of 12.4%; to date, 10 babies are already born. There were no significant difference in CPR, IR or CLR between groups KK (CPR=50.0%, IR = 50.0%, CLR=33.3%), KI (CP = 48.R5%, IR = 45.4%, CLR=10.2%) and KS (CPR=51.3%, IR = 50.0%, CLR=20.0%) or between groups II (CPR=40.0%, IR = 34.8%, CLR=31.3%) and IS (CPR=31.6%, IR = 36.8%, CLR=16.7%). Group IK was excluded due to very low numbers (3 blastocysts). Where embryos were vitrified with SAGE, there was no significant difference in CPR, IR, or CLR rate between group SK (CPR=50.0%, IR = 50.0%, CLR=0.0%) and group SS (CPR=62.5%, IR = 60.0%, CLR=6.7%) or between SK and group SI (CP = 38.8%, IR = 34.6%, CLR=0.0%). However, there was a significantly lower implantation rate in group SI compared to group SS (p = 0.044) although the difference in CP was not quite significant (p = 0.0779), and no significant difference was observed in CLR. Limitations, reasons for caution While maternal age was comparable across all groups, the study was not controlled in terms of patient history or embryo quality. CLR was calculated on the basis of combining livebirth and ongoing pregnancy rates. Wider implications of the findings The introduction of a universal single-step warming (USSW) will reduce costs, facilitate embryo exchange between centres and to streamline the lab workflow Trial registration number No Warming up ; Global warming ; Environmental science ; Climate change ; Medicine ; Biology ; Ecology thermodynamics and calorimetric analyses ; Medical Imaging Techniques and Applications