This study was designed to compare cumulus cell removal at different times and to evaluate their effects on embryo developmental potential and the outcomes of in vitro fertilization (IVF).Methods
We retrieved 606 IVF cycles with standard long down regulation protocol from January 2010 to December 2010. These cycles were divided into two groups: group A, 364 cycles with high risk of fertilization failure, whose cumulus cells were removed 4 h after short gamete coincubation; group B, 242 cycles as control, whose cumulus cells removal were performed 17 to 18 h after insemination. The epidemiological, clinical, laboratory factors and the outcomes of these cycles were analyzed.Results
The available embryo rate of group A was significantly lower (P=0.002). There were no significant differences in other laboratory parameters and outcomes between the two groups (P>0.05).Conclusions
For patients with high risk of fertilization failure, there could be a risk of compromising the rate of available embryos, if fertilization is judged by the presence of 2 PB by cumulus cell removal only 4 h post-insemination. Therefore, this strategy is not recommended to all IVF cycles and future studies are needed to confirm its reliability.