P-302 Correlation of blastocyst shrinkage-pattern during vitrification and post-warming embryo performance

Abstract Study question Can blastocyst shrinkage-pattern during vitrification be predictive of post-warming survival and reproductive potential? Summary answer Blastocysts assuming a specific are liable to lower morphology and, potentially, degeneration. What is known already Blastocyst highly standardized technique. However, there still possible factors than can compromise the outcome technique which should minimized. For example, degree blastocoel expansion before may negatively influence embryo post-warming. There studies demonstrate that expanded blastocysts exhibit rate because their higher volume amount water, more prone detrimental ice crystal formation vitrification. Moreover, shrinkage differs as some them shrink in uniform, spherical way while others non-canonical design, size, duration A retrospective study was conducted at IAKENTRO fertility clinic, Thessaloniki. total 2167 vitrified between November 2018-December 2022, out 532 warmed same period, were included present study. No biopsied or PGT-a tested embryos included. Embryo performed following protocol whole period clinical outcomes, 178 single-embryo transfers 123 double-embryo analyzed Participants/materials, setting, methods During exposure solution two patterns detected, allocating into Group-1 for presenting without any detachment trophectoderm cells from zona pellucida, leading ZP reforming eventually resembled “deflated” ball Group-2 collapsed uniform way, having TE fully detached ZP, remained throughout Main results role chance In cohort assessed blastocysts, 437 allocated 1730 Group-2, translated 20,2% event occurrence. The mostly 4 (76,7%) 3 (23,3%), according Gardner system, no smaller assigned this group. As primary examined with significantly degeneration (22/187, 11,7%) respect (7/345, 2%) (χ2 test, p < 0.0001, OR = 5,798, 95%CI 2,511 14,55). order assess potential decline post-warming, we corresponded Gardner’s system evaluation numerical score calculated integrity after Before vitrification, embryos’ similar both groups (74,8% 73,1% respectively) while, warming, exhibited (86,52% score) (93,82% (t-test, 0,0001). when analyzing PR CPR significant differences observed Limitations, reasons caution aspect per se general limitation. given analysis data not limited freeze-all cases, chosen fresh embryo-transfers, means those highest implantation potential, excluded study’s Wider implications findings Our show resembling have compromised survival. Given phenomenon exclusively whose thin stretched, identifying grade over happening could beneficial practice Trial registration number Not applicable