Outcome of reinsemination by ICSI 20-22 h after insemination with IVF

AIM: To compare the results of reinsemination by rescue ICSI of unfertilization oocytes in conventional IVF and those by ICSI during the same period and to evaluate the outcome of rescue ICSI. METHODS: In the total of 613 IVF-ET cycles from April 2000 to May 2003, there were 215 unfertilized oocytes from 24 conventional IVF cycles with total or near total fertilization failure. In cases where the semen seemed to be normal, reinseminated by ICSI was performed 20-22 h after conventional IVF insemination, and named rescue ICSI group. A matched control group with a total of 178 cycles undergoing ICSI during the same period was named ICSI group. RESULTS: A fertilization rate of 48.4% was achieved in rescue ICSI group, being lower than 56.4% in the control group ( P 0.05). All of the 24 cycles with total or near total fertilization failure had fresh transfers with rescue ICSI embryos (16 cycles with total fertilization failure and 8 patients with near total fertilization failure). The clinical pregnant rate and implantation rate in the control group were 28.1% and 9.8% respectively, whereas in rescue ICSI group the pregnant rate and implantation rate were 12.5% and of 4.3% ( P 0.05). Unfortunately, all of the 3 pregnancies in the rescue ICSI had abortion. CONCLUSION: Although the outcome after rescue ICSI is very poor, it should be considered in case of total or near total fertilization failure in conventional IVF so as to avoid cycle cancellation and obtain an additional chance of pregnancy for infertile couple. What counts is the time selection of rescue ICSI to establish fertilization within an optimal window and produce viable embryos and pregnancies.