O-160 Do day of vitrification, grade of expansion and blastocyst quality affect embryo survival rate? An observational study in oocyte recipient patients

Abstract Study question Which parameters are the most predictive of embryo survival rate in oocyte recipient cryotransfer cycles? Summary answer We have identified that only day vitrification and grade expansion an impact on What is known already Embryo a well stablished technique has led to rates around ±96%. Recent studies, based vitrification, blastocyst quality, trying identify which vitrified highest potential survive implant. However, controversial results present literature, improvements laboratory quality culture could unleash into no significant differences regardless morphological parameters. Nevertheless, having acceptable does not mean good implantation rate, biomarkers best implant needed design, size, duration An unicenter-based retrospective observational clinical study was performed at IVI Madrid, approved by local institutional review board (IRB). The included all warmings stage from patients January 2019 April 2022. A total 4.196 warmed blastocysts were assessed, out 4.006 transferred Participants/materials, setting, methods All allocated groups according quality. primary outcome analysed calculated as number viable embryos divided warmed. Vitrification warming following Kitazato method (Cryotop, Kitazato, Biopharma). classification assessed previous IVIRMA criteria. Statistical analyses conducted using univariate multivariate regression model Main role chance maternal age 42.27±3.89 years old body mass index 23±3.74 kg/m2). In logistic analysis, statistically association between found. Chance significantly reduced for 6 (n = 737) compared 5 3459) (93,2 % versus 96,0% [OR 0.976 (0.960-0.993); p=0.05]). Regarding expansion, cavitated 840) 97,7% 1;p<0.001], expanded 1866) 96,2% 0.095 (0.978-1.013)], hatching 1465) 94% 0.978 (0.960-0.997); p=0.02) fully hatched 25) 60% 0.704 (0.648-0.765);p<0.001)]. found neither lower inner cell 0.964 (0.842-1.104); p=0.596) nor trophoectoderm 1.004 (0.981-1.028); p=0.746)] rate. Analysing combination these three variables will give us possibility choose warm. implantation, pregnancy, miscarriage, live birth be further studies Limitations, reasons caution weakness this it nature. single-group design employed limits researchers’ ability determine cause effect. Further Wider implications findings Based our findings, influenced mostly degree expansion. To able select warm, comparison different when we similar morphology cohort Trial registration Not applicable