Objective    To compare and analyze the fertilization result and the clinical outcome of sibling oocytes after conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) in patients with tubal obstruction.     Methods    From August 2006 to August 2008

48 sibling oocytes from 42 woman with primary infertility and 6 with secondary infertility were inseminated with the corresponding same semen sample by ICSI and conventional IVF respectively in our hospital. The result of fertilization and the clinical outcome were retrospectively studied.     Results    The rate of complete fertilization failure was 16.7% (8/48) in IVF group while 0 in ICSI group. For the 40 patients whose oocytes were inseminated by ICSI and IVF

there were 470 oocytes harvested

half used for ICSI and half for IVF. The fertilization rate in the ICSI group was 78.6% (173/220)

significantly higher than that in IVF group (156/235

66.4%). In IVF group

17 best embryos were selected for embryo transfer and 7 patients had clinical pregnancy with a rate of 41.2%. In ICSI group

the clinical pregnancy rate was 40.0% (8/15)

and for IVF+ICSI group. The rate was 37.5% (6/16). There was no significant difference in implantation rate and pregnancy rate of the embryos obtained with either technique.     Conclusion    ICSI should be carried out at the same time with IVF for those with suspect or high risk of IVF failure.