Differential effects of short co-incubation of gametes and early removal of cumulus cells in patients with different fertilizing capabilities.

The objective of this retrospective study was to evaluate the embryological and clinical outcomes of short co-incubation of gametes and early removal of cumulus cells (SCGERCC) in patients with good IVF capability and those with complete fertilization failure treated by rescue intracytoplasmic sperm injection (ICSI). The study included 257 couples with >60% fertilization rate (SCGERCC group) in the SCGERCC cycle, 72 couples with complete fertilization failure in the SCGERCC cycle given early rescue ICSI treatment (early rescue group), and 219 couples who underwent IVF cycles with overnight co-incubation of gametes with >60% fertilization rate (traditional IVF group). The results showed that the SCGERCC group had a higher multi-pronuclei rate (13.34%, P < 0.001) than the early rescue ICSI (5.15%) and traditional IVF (6.15%) groups. The good quality embryo rate was higher in the SCGERCC group, but implantation, clinical pregnancy and live-birth rates (37.21%, 36.92% and 38.20% for SCGERCC, early rescue and traditional IVF groups, respectively) were comparable in all three groups. The study indicated that SCGERCC followed by rescue ICSI helped couples with initial complete fertilization failure attain clinical outcomes comparable with the other two groups, but it significantly increased the multi-pronuclei rate in couples with good fertilizing capabilities.