The impact of spermatozoa preincubation time and spontaneous acrosome reaction in intracytoplasmic sperm injection: a controlled randomized study.

OBJECTIVE To determine the optimum time interval between semen processing and incubation before intracytoplasmic sperm injection (ICSI) and correlate it with the acrosomal reaction rate. DESIGN Controlled randomized study. SETTING The Egyptian IVF-ET Center. PATIENT(S) Couples with male factor infertility undergoing ICSI using ejaculated semen. INTERVENTION(S) The patients were prospectively randomized according to differences in sperm preincubation time before ICSI into 1-hour, 3-hour, and 5-hour groups. The status of the acrosome was studied using electron microscopy. MAIN OUTCOME MEASURE(S) The primary outcome measures were fertilization rate and acrosome reaction rate. Secondary outcome measures were the implantation and pregnancy rates. RESULT(S) The rate of acrosomally reacted spermatozoa was the highest (68.2%) after 5 hours of incubation and lowest (25.6%) after 1 hour of incubation. The difference was statistically significant. The fertilization rate was the highest (74%) using spermatozoa incubated for 3 hours as compared with 1 hour (70%) and 5 hours (67%), but the difference was not statistically significant. CONCLUSION(S) Acrosome reaction is time dependent; the optimum incubation time of spermatozoa before ICSI was 3 hours, which resulted in the highest fertilization rate.