OBJECTIVETo analyze the clinical outcome of intracytoplasmic sperm injection (ICSI) in patients with previous fertilization failure after conventional IVF.

METHODSData from 20 ICSI cases (22 ICSI cycles) with previous complete failure of fertilization or with fertilization rate < or = 20% between January 2002 and December 2004 were retrospectively analyzed. The control group consisted of 100 consecutive ICSI cycles for male factor infertility in the same period.

RESULTSThe fertilization rate dramatically increased from 5.4% after conventional IVF to 76.9% after ICSI treatment (chi-squared = 264.66, P < 0.001). However, the fertilization rate in the subgroup with previous low fertilization was significantly lower than those in the control and in the subgroup without previous fertilization (67.9% vs 77.5%, 67.9% vs 84.2%). Compared with the control group, the subgroup without previous fertilization had a higher pregnancy rate and implantation rate, but only the difference in the implantation rate was statistically significant (40.5% vs 18.9%).

CONCLUSIONICSI can overcome previous fertilization failure with conventional in vitro fertilization and thus improve the clinical outcome.