Many physicians suggest that performing ICSI instead of IVF for all cases just because they thought that ICSI yields more available embryos than IVF. However, we found that IVF results in better fertilization per retrieved oocyte (72.12 ± 19.60% versus 59.54 ± 21.38%, P < 0.01) and day 3 available embryo per retrieved oocyte rates (54.89 ± 23.53% versus 50.54 ± 22.68%, P < 0.05) than ICSI after analysis of 218 cycles using sibling oocytes in combined IVF/ICSI for patients with no indications for ICSI. We also found a positive correlation between the degeneration rate after ICSI, oocyte immaturity rate, and rate of 2 pn per retrieved oocyte obtained from IVF compared to ICSI, as well as the day 3 available embryo rate between IVF and ICSI. It is possible that outcome may be due to more in vitro-matured oocytes achieved in IVF fertilization compared with ICSI fertilization, and a considerable portion of the mature oocytes were degenerated after ICSI. Therefore, it is suggested that ICSI should not be performed in all cases of in vitro conception. IVF is preferable to ICSI for cases in which a relatively low possible fertilization failure occurs in conventional IVF.
Keywords: Sibling oocytes; available embryos; combined IVF/ICSI; oocyte degeneration rate; oocyte immaturity rate.