The present results indicate that cumulus cells removal at 6 h of insemination is a relatively safe operation, which yielded comparable normal fertilization rate, multinucleation and clinical pregnancy rates compared with 20 h group. This protocol may be beneficial for early obsevation of fertilization failure and make early rescue ICSI possible.

Vitrification is an important way to cryopreserve human embryos and the recommended time of embryo exposure to the vitrification solution is 1 min. However, practically speaking, the duration of embryos exposure to equilibration solution can vary from 5 to 15 min. The purpose of this study was to investigate the effect of different equilibration times on the outcomes of frozen-thawed embryo transfer cycles. The data were collected from our medical records from January 2012 to June 2013 and a total of 517 cycles were included. These cycles were divided into four groups according to the equilibration time: (i) 5-6 min; (ii) 7-8 min; (iii) 9-10 min and (iv) 11-12 min. The results show that there were no differences in terms of survival rate and fully intact embryo rate among the four groups. However, lower clinical pregnancy, embryo implantation and live birth rates were observed in the 5-6 min exposure group (54.6%, 31.9% and 48.2%, respectively) compared with the three other groups. The corresponding rates in the 9-10 min group (73.5%, 47.6% and 64.7%) were the highest. This study indicated that different equilibration times influenced the clinical outcomes of human embryo vitrification and vitrification with shortened equilibration time compromised the clinical outcomes. Appropriate prolongation of the equilibrium time would probably improve the clinical outcomes.

Summary This study aimed to evaluate to what extent the different interval times between trophectoderm (TE) biopsy and vitrification influence the clinical outcomes in preimplantation genetic testing (PGT) cycles. Patients who underwent frozen embryo transfer (FET) after PGT between 2015 and 2019 were recruited. In total, 297 cycles with single day 5 euploid blastocyst transfer were included. These cycles were divided into three groups according to the interval times: <1 h group, 1–2 h group, and ≥2 h group. Blastocyst survival, clinical pregnancy, miscarriage, and ongoing pregnancy rates were compared. The results showed that, in PGT-SR cycles, survival rate in the ≥2 h group (96.72%) was significantly lower than in the <1 h group (100%, P = 0.047). The clinical pregnancy rate in the ≥2 h group was 55.93%, significantly lower than in the <1 h group (74.26%, P = 0.017). The ongoing pregnancy rates in the 1–2 h group and the ≥2 h group were 48.28% and 47.46%, respectively, significantly lower than that in the <1 h group (67.33%, P < 0.05). The miscarriage rate in the 1–2 h group was 18.42%, significantly higher than that in the <1 h group (5.33%, P = 0.027). In PGT-A cycles, the clinical pregnancy and ongoing pregnancy rates in the <1 h group were 67.44% and 53.49%, respectively, higher than that in the 1–2 h group (52.94%, 47.06%, P > 0.05) and the ≥2 h group (52.63%, 36.84%, P > 0.05). In conclusion, vitrification of blastocysts beyond 1 h after biopsy significantly influences embryo survival and clinical outcomes and is therefore not recommended.

The purpose of this study was to determine the incidence of oocytes with severe ovoid zona pellucida (ZP), investigate the development potential of their sibling oocytes and the clinical outcomes from affected cycles. The data were collected from our medical records. Cycles having at least one oocyte with severe ovoid ZP were defined as the 'severe ovoid group', cycles having at least one oocyte with mild ovoid ZP were defined as the 'mild ovoid group', whereas cycles without oocytes with ovoid ZPs were defined as the 'control group' (n = 150 for each group). The results showed that sibling embryos in the 'severe ovoid group' were characterized by delayed development and lower available embryo rate. The implantation, clinical pregnancy and live birth rates in this group were also significantly lower than that in the other two groups. There were five cycles in which only one embryo with severe ovoid ZP was transferred and two healthy babies were born. The mild ovoid group showed comparable embryo development and clinical outcomes compared with the control group. This study suggests that cycles containing oocytes with severe ovoid ZPs had delayed embryo development, lower available embryo rate, compromised implantation, clinical pregnancy and live birth rates.

For the past few years, great development has been achieved in deep foundation excavation. However, due to foundation excavation’s locality, individual diversity, complexity and uncertainty, the probability of accidents in foundation pit engineering tends to be greater than that in main works, and the accident rate may even reach about 20%, which makes the study on factors leading to foundation excavation accidents quite necessary and meaningful. By use of Analytic Hierarchy Process (AHP), this paper has figured out the ratio (weight) of the investigation, design, construction and other factors leading to foundation excavation accidents to the whole factor set, which is of great guiding significance to the study on prevention and treatment of foundation excavation accidents in future.