Obstetrics and Gynecology, Staten Island University Hospital, 475 Seaview Avenue, Staten Island, NY, 10305, USA.
Island Reproductive Services, 237 Richmond Valley Road, Staten Island, NY, 10309, USA.
J Assist Reprod Genet. 2019 Apr;36(4):621-628. doi: 10.1007/s10815-019-01400-5. Epub 2019 Jan 15.
In vitro fertilization with trophectoderm embryo biopsy and pre-implantation genetic screening with comprehensive chromosomal screening (PGS-CCS) for aneuploidy is becoming increasingly more popular. Embryos are cryopreserved and implanted in a subsequent frozen thawed embryo transfer cycle (FET). No studies have investigated differences in pregnancy outcomes by timing of trophectoderm biopsy relative to stages of blastocyst development.
Retrospective study of all patients (n = 363) at a single IVF center between January 1, 2013 and December 31, 2016 undergoing single embryo transfer with PGS-CCS where embryos were cryopreserved with subsequent FET. Embryo expansion and grading was assessed both at the time of biopsy and transfer. Pregnancy rates were analyzed by embryo expansion and embryo grading.
Implantation, clinical pregnancy, and live birth rates improved significantly with increased embryo expansion at the time of embryo biopsy (P < 0.001). Pregnancy loss decreased with increases in embryo expansion prior to biopsy (P < 0.001). Superior live birth rates with PGS-CCS were seen when embryos were hatching at the time of biopsy (p < 0.001). For fresh and frozen embryo transfers without PGS-CCS, embryo expansion did not affect pregnancy outcomes.
PGS-CCS significantly increases implantation and live birth rates only if embryos are hatching at the time of biopsy. The embryo biopsy itself on a non-hatching embryo significantly damages the embryo in ways which are not reflected in future embryo expansion. IVF labs should wait until embryos hatch before performing trophectoderm biopsy.
体外受精联合滋养层胚胎活检和植入前遗传学筛查（PGS-CCS）用于非整倍体检测正变得越来越流行。胚胎被冷冻并在随后的冷冻解冻胚胎移植周期（FET）中进行移植。目前还没有研究探讨相对于囊胚发育阶段，滋养层活检的时机对妊娠结局的影响。
回顾性分析 2013 年 1 月 1 日至 2016 年 12 月 31 日在一家体外受精中心接受 PGS-CCS 单胚胎移植且胚胎被冷冻并随后进行 FET 的所有患者（n=363）的资料。胚胎活检时和移植时评估胚胎扩张和分级情况。通过胚胎扩张和胚胎分级分析妊娠率。
胚胎活检时胚胎扩张增加，着床率、临床妊娠率和活产率显著提高（P<0.001）。胚胎活检前胚胎扩张增加，妊娠丢失率降低（P<0.001）。在活检时胚胎孵化时，PGS-CCS 具有更高的活产率（p<0.001）。对于未进行 PGS-CCS 的新鲜胚胎和冷冻胚胎移植，胚胎扩张并不影响妊娠结局。
只有当胚胎在活检时处于孵化状态时，PGS-CCS 才能显著提高着床率和活产率。对未孵化的胚胎进行胚胎活检本身会对胚胎造成损害，而这种损害在未来的胚胎扩张中并未得到体现。体外受精实验室应等待胚胎孵化后再进行滋养层活检。
