Edgar David H, Archer Janell, McBain John, Bourne Harold
Reproductive Services/Melbourne IVF, Royal Women's Hospital, 132 Grattan Street, Carlton, Victoria 3053, Australia.
Reprod Biomed Online. 2007 Jun;14(6):718-23. doi: 10.1016/s1472-6483(10)60674-8.
Multiple pregnancy minimization by single embryo transfer is becoming more prevalent, but is less common in the case of cryopreserved embryos. This study defines embryonic characteristics in single cryopreserved embryo transfers associated with success rates equivalent to those achieved when transferring two cryopreserved embryos. In a retrospective analysis of 6916 cryopreserved day-2 embryo transfer procedures, transfer of two cryopreserved embryos resulted in higher clinical pregnancy rates when compared with transfer of a single thawed embryo but was also associated with elevated multiple pregnancy rates (26.7% in women under 36). Optimal outcome (implantation rate of 30.9%) from single cryopreserved embryo transfer (SCET) in women under 36 was associated with cryopreservation at the 4-cell stage, loss of fewer than two blastomeres and subsequent cleavage of at least two surviving blastomeres. In comparison, transfer of two cryopreserved embryos in women under 36 resulted in pregnancy and implantation rates of 25.5 and 16.1% respectively. Interestingly, in cryopreserved 4-cell stage embryos, loss of a single blastomere did not reduce implantation potential and cleavage of only a single post-thaw blastomere was not indicative of increased implantation potential. Establishment of these critical thresholds provides a rational basis for SCET.
通过单胚胎移植来尽量减少多胎妊娠的情况越来越普遍，但在冷冻胚胎移植中则不太常见。本研究确定了单冷冻胚胎移植中的胚胎特征，这些特征与移植两个冷冻胚胎时所达到的成功率相当。在对6916例冷冻第2天胚胎移植程序的回顾性分析中，与移植单个解冻胚胎相比，移植两个冷冻胚胎可获得更高的临床妊娠率，但同时多胎妊娠率也会升高（36岁以下女性中为26.7%）。36岁以下女性单冷冻胚胎移植（SCET）的最佳结果（着床率为30.9%）与4细胞期冷冻保存、卵裂球损失少于两个以及至少两个存活卵裂球随后发生分裂有关。相比之下，36岁以下女性移植两个冷冻胚胎的妊娠率和着床率分别为25.5%和16.1%。有趣的是，在冷冻保存的4细胞期胚胎中，单个卵裂球的损失并未降低着床潜力，解冻后仅单个卵裂球发生分裂并不意味着着床潜力增加。确定这些关键阈值为单冷冻胚胎移植提供了合理依据。
