Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Iowa Hospitals and Clinics, Iowa City, IA, 52242, USA.
Department of Obstetrics and Gynecology, University of Washington, Seattle, WA, 98195, USA.
J Assist Reprod Genet. 2021 Aug;38(8):2193-2198. doi: 10.1007/s10815-021-02156-7. Epub 2021 Mar 22.
This study aims to know what proportion of culture day 5 pre-blastocyst-stage embryos develop into blastocysts by culture day 6 and what patient and cycle characteristics are associated with delayed blastocyst formation.
A retrospective observational cohort analysis was performed including a total of 9886 embryos from 1008 IVF cycles in 835 patients, who underwent treatment between January 1, 2016, and December 31, 2018. Autologous fresh in vitro fertilization (IVF) cycles at a single academic center were included in the analysis. Embryos were group-cultured using single-step culture media. Blastulation was defined as the presence of a new blastocyst. Usable blastulation was defined as the presence of a new good or excellent quality, expanded, hatching, or hatched blastocysts.
The mean blastulation rate between days 5 and 6 of extended embryo culture was 30.9%. The mean percentage of embryos developing into usable blastocyst-stage embryos was 19.8%. The factors associated with blastulation on day 6 included the total number of embryos and the number of pre-blastocysts on day 5, as well as the use of ICSI. Age, the number of total embryos, those remained in culture and pre-blastocysts, as well as the blastulation rate on day 5 were associated with usable blastulation.
It is important to know the usable blastocyst development rate between culture days 5 and 6 in order to adequately counsel patients debating whether to proceed with fresh ET on day 5 or forego ET with the expectation that embryos will be biopsied for PGT and/or cryopreserved on culture day 6. Our findings provide evidence to help guide patients in this difficult decision.
本研究旨在了解第 5 天原核期前胚胎中，有多少比例能在第 6 天培养成囊胚，以及哪些患者和周期特征与囊胚形成延迟有关。
本研究进行了一项回顾性观察性队列分析，共纳入了 835 名患者的 1008 个 IVF 周期中的 9886 个胚胎，这些患者于 2016 年 1 月 1 日至 2018 年 12 月 31 日在单家学术中心接受治疗。纳入分析的是自体新鲜体外受精（IVF）周期。胚胎采用一步法培养培养基进行分组培养。囊胚形成定义为有新囊胚出现。可利用囊胚形成定义为有新的优质、扩张、孵化或已孵化囊胚出现。
延长胚胎培养第 5 天至第 6 天的囊胚形成率平均为 30.9%。平均有 19.8%的胚胎能发育成可利用的囊胚阶段胚胎。第 6 天囊胚形成的相关因素包括胚胎总数和第 5 天的原核胚胎数，以及 ICSI 的使用。年龄、胚胎总数、培养中剩余胚胎和原核胚胎数以及第 5 天的囊胚形成率与可利用囊胚形成有关。
了解第 5 天至第 6 天培养过程中可利用囊胚的发育率非常重要，这有助于充分告知正在考虑是否在第 5 天进行新鲜胚胎移植（ET）或放弃 ET，期待第 6 天进行胚胎活检进行 PGT 和/或冷冻的患者。我们的研究结果为帮助患者做出这一艰难决策提供了证据。
