Rescue ICSI: Choose the Optimal Rescue Window before Oocyte Aging

Objective To evaluate the application value of rescue ICSI in fertilization failure after conventional IVF and choose the best rescue window before oocyte aging according to the results of rescue ICSI performed in different time. Methods The data of 93 IVF cycles were analyzed retrospectively. Rescue ICSI was performed in these cycles after conventional IVF failure. Because of the different rescue time, these cycles were divided into two groups： early rescue group （group A, 77 cycles, rescue ICSI performed 4-8 h after conventional IVF） and late rescue group （group B, 16 cycles, rescue ICSI performed 20-22 h after conventional IVF）. Results There were no statistically significant differences in age of female, duration of infertility, number of oocytes retrieved every cycle. The normal fertilization rate, pregnancy rate and implantation rate were decreased in group B compared with those in group A （P〈0.05）. In group A, the normal fertilization rate of rescue ICSI performed 4-6 h after conventional IVF （group A1） was increased compared with that of rescue ICSI performed 6-8 h （including 6 h） after conventional IVF （group A2）（66.5% vs 55.9%）（P〈0.05）; while the abnormal fertilization rate in group A1 was decreased compared with group A2 （9.0% vs 14.4%）（P〈0.05）. Clinical pregnancy rate was slight higher in group A1 than in group A2, though this failed to be significantly different. Conclusion Rescue ICSI is effective if fertilization was failure after conventional IVF, the most important thing is to choose the reasonable rescue window before oocyte aging when ICSI is performed.

Spindle and Chromosome Analysis of Non-Fertilized Oocytes from Conventional in vitro Fertilization for Non-Male Factor Infertiliy: Significance of Rescue ICSI?

Objective To determine whether rescue intracytoplasmic sperm injection （ICSI） is associated with improved outcomes for non-male factor infertility. Methods The changes of micro-structure, including meiotic spindle and chromosome distribution, sperm penetration, as well as oocyte activation were compared in IVF （in vitro fertilization）fertilization failure （1VF FF） patients, ICSI patients with non-fertilized oocytes （ICSI NF） and oocytes in vitro maturation （IVM）. Results A total of 164 unfertilized oocytes （93 oocytes in IVF and 71 oocytes in ICSI） and 56 IVM oocytes were available for this study. The abnormality of spindle and chromosomes was significantly higher in IVF FF group than that in ICSI NF group or IVM group （abnormal spindle rates were 80.6%, 64.8% and 57.1%, respectively; abnormal chromosome rates were 91.4%, 80.3% and 75.0%, respectively）. No sperm penetration after IVF and sperm expulsion after ICSI were 78.5% and 40.8%, respectively. Activation failure occurred in 16.1% of the IVF FF cases and 49.3% of ICSI NF oocytes. Conclusion Rescue ICSI of fertilization-failed oocytes fails to lead outcome improvement due to the internal defects of oocytes.

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 2023 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=1475）, 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 i 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% vs 76.2%）, 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.