Polyspermy: effect of varying stimulation protocols and inseminating sperm concentrations.

Results from 198 cycles of in vitro fertilization (IVF) were examined to identify factors in the subsequent development of polyspermy. Polyspermy occurred in 24 of 235 fertilized oocytes and was equally likely in mature and immature oocytes. No significant difference in polyspermy was demonstrated between the stimulation protocol using human menopausal gonadotropin (hMG) and those using clomiphene citrate (CC) or combined hMG/CC. The incidence of polyspermy was no different after insemination of oocytes with concentrations of progressively motile sperm ranging from 250,000 to 500,000. Although polyspermy continues to be a problem in IVF, we have been unable to identify possible predisposing mechanisms for its development.