Early Rescue Intracytoplasmic Sperm Injection in Partial Fertilization Failure Is Necessary and Safe: A Retrospective Analysis of 1223 Patients

Abstract BACKGROUND : Total or near total fertilization failure remains inevitable in conventional in vitro fertilization (IVF). The experts searched for the release of the second polar body 6 h after initial insemination, and rescued those oocytes with unclear second polar body by ICSI (early R-ICSI). Studies found that early R-ICSI can effectively decrease complete IVF fertilization failure and excessive ICSI treatment. METHODS : We performed a retrospective study in 16,769 patients (short-term IVF, n=12,094; ICSI, n=3,452; early R-ICSI, n=1,223) who received IVF/ICSI treatment in our hospital from January 2009 to October 2018. Fertilization and clinical outcomes were compared among those three groups. RESULTS : When considering the R-ICSI embryos in the early R-ICSI group independently, the rates of fertilization and day-3 cleaved embryos in 2PN oocytes were comparable, the rates of fertilization (2PN) and high-quality embryos were lower, whereas the multi-PN fertilization rate (3.27%) was significantly higher than the ICSI group (1.26%). The difference of clinical pregnancy rate between the part of transferred R-ICSI embryos (40.81%) and the ICSI group (44.73) remained nonsignificant. Furthermore, the rate of congenital birth defects in the early R-ICSI group (0.99%) was not significantly different from those in the short-term IVF (0.76%) and ICSI groups (1.07%). CONCLUSIONS : Despite the multi-PN fertilization rate, our study highlights early R-ICSI as a safe and effective alternative in assisted reproduction to reduce ICSI utilization. Additional large amount and long-term follow-up studies are needed to further validate the use of early R-ICSI.