Abstract:

Objective　To explore the differences in euploidy and aneuploidy abnormalities and mosaic abnormalities between day 5 and day 6 embryos submitted for preimplantation genetic testing-structural rearrangements (PGT-SR) in patients with chromosomal structural abnormalities, and to further analyze the pregnancy outcomes after the transfer of euploid embryos in the two groups. Methods　A retrospective cohort study method was used. One hundred and five couples who underwent PGT-SR assisted reproduction treatment at Reproductive Medicine Center, Tianjin Medical University General Hospital from March 2023 to October 2024 were selected for the study. A total of 127 oocyte retrieval cycles were performed, and a total of 633 blastocysts underwent trophectoderm cell biopsy. The women were (32.09±3.48) years old; the men were (32.89±3.63) years old. The number of gonadotropin (Gn) days ranged from 6 to 17 days. The number of retrieved oocytes ranged from 2 to 71. According to the embryo development stage, there were 316 day 5 blastocysts, 298 day 6 blastocysts, and 19 day 7 blastocysts. Due to the small number of day 7 blastocysts and the low euploidy rate, they were not included in the subsequent statistical analysis. The data on the sources and types of chromosomal abnormalities, as well as the baseline data for the formation of blastocysts from D5 and D6, were collected. The formation rates of euploid embryos, aneuploid abnormal embryos, and chimeric abnormal embryos from D5 and D6. Statistical analysis was conducted using t test and χ² test. Results　Among the 633 embryos, there were 220 pieces of female chromosomal balanced translocation, 25 pieces of chromosomal Robertsonian translocation, and 18 pieces of chromosomal inversion and other structural abnormalities; there were 268 pieces of male chromosomal balanced translocation, 59 pieces of chromosomal Robertsonian translocation, and 43 pieces of chromosomal inversion and other structural abnormalities. There were no statistical differences in the baseline data between the patients with day 5 and day 6 blastocysts (all P>0.05). The euploidy rate of the day 5 blastocysts was higher than that of the day 6 blastocysts [37.03% (117/316) vs. 26.17% (78/298)], with a statistical difference (P=0.004). A total of 61 euploid day 5 embryos and 29 euploid day 6 embryos were transplanted in our center. The human chorionic gonadotropin (HCG) positive rate after the transfer of the euploid day 5 blastocysts was 73.8% (45/61), and the clinical pregnant rate was 65.6% (40/61); the HCG positive rate after the transfer of the euploid day 6 blastocysts was 41.4% (12/29), and the clinical pregnancy rate was 27.6% (8/29); there was a statistical difference between the two groups (P<0.05). Conclusion　The euploidy rate after the detection of Day 5 blastocysts is higher, and so is the pregnancy rate after the transfer.

Key words:

Preimplantation genetic testing-structural rearrangements, Day 5 blastocysts, Day 6 blastocysts, Euploidy rate, Pregnancy outcomes

摘要：

目的　探讨染色体结构异常患者送检第5日（D5）、第6日（D6）囊胚行植入前染色体结构重排检测（preimplantation genetic testing-structural rearrangements，PGT-SR）的整倍体、非整倍体异常及嵌合异常差异，并进一步分析两组整倍体胚胎移植后的妊娠情况。方法　采用回顾性队列研究，选取2023年3月至2024年10月于天津医科大学总医院生殖医学中心行PGT-SR助孕治疗的105对夫妇，共127个取卵周期，633枚胚胎行滋养外胚层细胞活检。其中女方年龄（32.09±3.48）岁，男方年龄（32.89±3.63）岁，促性腺激素（Gn）天数6～17 d，获卵数目2～71枚。根据胚胎发育期分为D5囊胚（316枚）、D6囊胚（298枚）及D7囊胚（19枚）。由于D7囊胚数目较少，整倍体率低，后续未纳入统计学分析。统计染色体异常来源及种类、D5与D6形成囊胚患者的基线数据，比较D5、D6送检囊胚整倍体胚胎形成率、非整倍体异常胚胎形成率及嵌合异常胚胎率。采用t、χ²检验进行统计学分析。结果　633枚胚胎异常来源：女方染色体平衡易位220枚、染色体罗氏易位25枚、染色体倒位及其他结构异常18枚，男方染色体平衡易位268枚、染色体罗氏易位59枚、染色体倒位及其他结构异常43枚。D5及D6囊胚来源患者基线数据比较，差异均无统计学意义（均P>0.05）。D5囊胚整倍体率（37.03%，117/316）高于D6（26.17%，78/298），差异有统计学意义（P=0.004）；共移植61枚D5整倍体胚胎，29枚D6整倍体胚胎；D5整倍体囊胚移植后人绒毛膜促性腺激素（HCG）阳性率为73.8%（45/61）、临床妊娠率为65.6%（40/61），D6整倍体囊胚移植后HCG阳性率为41.4%（12/29）、临床妊娠率为27.6%（8/29），两组比较差异均有统计意义（均P<0.05）。结论　D5囊胚检测后整倍体率与胚胎移植后妊娠率更高。

关键词:

植入前染色体结构重排检测, D5囊胚, D6囊胚, 整倍体率, 妊娠结局