Comparison of sibling oocyte outcomes after intracytoplasmic sperm injection and in vitro fertilization in severe teratozoospermic patients in the first cycle

To follow up the outcome of sibling oocytes subjected to both conventional in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in the first cycles of severe teratozoospermic patients with normal sperm morphology (NSM)less than or equal to4%, a total of 1193 sibling metaphase II oocytes (MII) in 85 cycles were randomly allocated into two groups: 588 underwent IVF and 605 ICSI and the embryo outcomes between the two groups were compared. The fertilization rate was significantly higher in the ICSI groups than in the IVF group (p < 0.05) and fertilization failure rate in the ICSI group (2.3%) was lower than in the IVF group (28.2%). Subsequently, the rates of embryo arrest as well as grade 1 and 2 embryo formation before day 3, greater than or equal to6 cell embryos on day 3 and blastocyst formation on days 5 and 6, did not differ significantly between the two groups. There was a trend towards a high pregnancy rate cycle in mixed ICSI/IVF embryo transfer (ET) (49.1%). In conclusion, this study showed that in couples with only severe teratozoospermia, there was a benefit in subjecting sibling oocytes to both IVF and ICSI in the first cycle because 24 (28.2%) cycles of total fertilization failure were avoided. Furthermore, despite initially significant higher fertilization rates in ICSI than IVF oocytes, subsequent rates of development from greater than or equal to6 cells up to blastocyst stage were the same suggesting that ICSI should be used with caution, as after day 3, ICSI-derived embryo development was compromised compared with IVF.