Expectations for oocyte fertilization and embryo cleavage after whole sperm versus sperm head intracytoplasmic sperm injection

Objective: To compare oocyte fertilization and embryo development after intracytoplasmic sperm injection (ICSI) with a whole sperm vs. a sperm head. Design: Retrospective study. Setting: Hospital-based IVF practice. Patient(s): Fifty-three women undergoing 54 IVF-embryo transfer plus ICSI procedures between January 1999 and June 2002. Intervention(s): None. Main Outcome Measure(s): Oocyte fertilization, zygote cleavage, and embryo stage after 72 hours of culture. Result(s): A significantly higher fertilization rate was observed using whole sperm (72.2%) than when using sperm heads (56.4%). Zygote cleavage rates for whole sperm vs. sperm head ICSI were 96.4% and 92.7%, respectively. Embryo cell stage after 72 hours of culture for whole sperm vs. sperm head ICSI was 6.5 +/- 2.1 cells and 5.6 +/- 1.8 cells, respectively. Embryo grade at this same time point was not different (2.3 +/- 1.0 and 2.5 +/- 0.9, respectively). Conclusion(s): The ICSI using whole sperm produces superior fertilization rates compared to ICSI using sperm heads, but once oocytes were fertilized, zygote cleavage rates were not different between the two sperm sources. Oocytes injected with a whole sperm produced embryos of higher cell stage but equivalent quality compared to oocytes injected with sperm heads. Therefore, having only sperm heads for use in ICSI should not be a deterrent to using this procedure. (C)2004 by American Society for Reproductive Medicine.