Effect of sperm preparation techniques by density gradient on intra-individual variation of sperm motility.

The purpose of this study was to examine the effect of sperm preparation by density gradient on the intra-individual variation in sperm motility. Patients presenting for density gradient (DG) sperm preparation were analyzed retrospectively. Patients who had more than one preparation were included. The variation within each patient was studied using the coefficient of variation (CV = standard deviation/mean x 100). Density gradient preparation resulted in a reduction in the CV of sperm motility (CV motility before DG: 19.8 +/- 15.82% vs. CV motility after DG: 15.9 +/- 17.97%, p < 0.001). However, CV of sperm concentration (44.2 +/- 26.51%) and CV progressively motile sperm (49.2 +/- 28.48%) remained very high after DG. This variability should be reflected in counseling patients undergoing intrauterine insemination.