Vitrification versus slow freezing gives excellent survival,post warming embryo morphology and pregnancy outcomes for human cleaved embryos

Purpose  The objective of this retrospective study was to evaluate the efficacy of vitrification and slow freezing for the cryopreservation of human cleavage stage embryos in terms of post-warming survival rate, post-warming embryo morphology and clinical outcomes. Methods  The embryos of 305 patients at cleavage stages were cryopreserved either with vitrification (153 patients) or slow-freezing (152 patients) methods. After warming; the survival rate, post-warmed embryo morphology, clinical pregnancy and implantation rates were evaluated and compared between the two groups. Result(s)  In the vitrification group versus slow freezing group, the survival rate (96.9% vs. 82.8%) and the post-warmed excellent morphology with all blastomeres intact (91.8% vs. 56.2%) were higher with an odds ratio of 6.607 (95% confidence interval; 4.184–10.434) and 8.769 (95% confidence interval; 6.460–11.904), respectively. In this group, the clinical pregnancy rate (40.5% vs. 21.4%) and the implantation rate (16.6% vs. 6.8%) were also higher with an odds ratio of 2.427 (95%confidence interval; 1.461–4.033) and 2.726 (95% confidence interval; 1.837–4.046), respectively. Conclusion(s)  Vitrification in contrast to slow freezing is an efficient method for cryopreservation of human cleavage stage embryos. Vitrification provides a higher survival rate, minimal deleterious effects on post-warming embryo morphology and it can improve clinical outcomes. Capsule Cryopreservation of human cleavage stage embryos with vitrification versus slow freezing provides better laboratory and clinical outcomes.     

慢速程序化冷冻与玻璃化冷冻对第3天分裂期胚胎发育潜能的影响

目的比较慢速程序化冷冻法（慢速法）和玻璃化冷冻法（玻璃化法）对第3天分裂期胚胎发育潜能的影响。方法选择因输卵管阻塞或男性少弱精因素行体外受精（IVF）或卵母细胞胞质内单精子注射（ICSI）治疗的患者,挑选在行IVF或ICSI后第3天剩余优质胚胎数目超过4个者80例进入本研究。随机将每例患者的2个胚胎用玻璃化法冷冻,另外2个用慢速法冷冻;冷冻复苏后随机抽取40例患者移植慢速法冷冻的胚胎,另40例患者移植玻璃化法冷冻的胚胎,比较2种冷冻方法对胚胎发育潜能的影响。结果冷冻复苏后待移植的胚胎共160个,其中慢速法冷冻80个,复苏后存活73个（91％,73／80）,移植后40例患者中15例（38％,15／40）获得临床妊娠,其中3例（20％,3／15）为双胎妊娠,余为单胎妊娠,胚胎着床率为25％（18／73）;玻璃化法冷冻胚胎80个,复苏后存活71个（89％,71／80）。移植后40例患者中19例（48％,19／40）获得临床妊娠,其中9例（47％,9／19）为双胎妊娠,余为单胎妊娠,胚胎着床率为39％（28／71）,与慢速法相比,玻璃化法的临床妊娠率和双胎妊娠率均有提高,但差异无统计学意义（P〉0．05）,而胚胎着床率则显著提高,差异有统计学意义（P〈0．05）。结论玻璃化法能够更好地保存胚胎复苏后的发育潜能,更适合第3天分裂期胚胎的冷冻保存。