Selective Short-term Fertilization Combined with Early Rescue ICSI An Optimal Strategy for Patients at High Risk for Fertilization Failure

Objective To investigate clinical outcomes in patients who were at more precise criteria risks for fertilization failure and were treated with selective, short-term fertilization(oocytes and sperm co-incubated for 4 h) and early rescue intracytoplasmic sperm injection(ICSI).Methods A retrospective analysis was performed on 2 023 women undergoing assisted reproductive technology(ART). They were assigned to 4 groups: short-term in vitro fertilization(short-term IVF, group A, n=217), regular IVF(oocytes and sperm coincubated overnight, group B, n=1 475), short-term IVF and early rescue ICSI(shortterm ICSI, group C, n=94), and regular ICSI(group D, n=237).Results In group A, 69.8%(217/311) achieved normal fertilization rates, and the complete fertilization failure rate(fertilization rate was 0%) was 12.9%(40/311). But all of the fertilization failure oocytes got rescue ICSI. In group B, the complete fertilization failure rate was 1.1%(19/1 692). The fertilization rate, 2 PN(pronucleus)rate, and 1 PN rate were significantly lower in group A than those in group B(70.9%vs 80.8%, 57.8% vs 66.3%, and 3.5% vs 6.2%, respectively). No significant differences were observed in clinical pregnancy rates and birth defect rates between groups A and B. The fertilization rates in groups C and D did not significantly differ(77.9% vs76.2%), which was also true for birth defect rates. The clinical pregnancy rate of group C was higher than that of group D(51.2% vs 42.3%), but this difference was not significant(P>0.05).Conclusion These results suggested that selective, short-term fertilization can result in effective outcomes for patients who were at high risk for fertilization failure.