PURPOSE: 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.
PURPOSE: 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.