Comparative evaluation of three sperm-washing methods to improve sperm concentration and motility in frozen-thawed oligozoospermic and normozoospermic samples

Three sperm-washing methods (direct layering without centrifugation, DL; ficoll entrapment, F; and percoll gradient, P) were evaluated for sperm recovery and motility using computer-automated semen analysis on frozen-thawed samples from normozoospermic and oligozoospermic men. The motile sperm recovery after freeze-thawing was significantly greater for normozoospermic compared with oligozoospermic samples (43 +/- 5.08% vs 15.76 +/- 3.53%; p < 0.001). The P-separated prelayer gave significantly higher recovery of motile sperm than the DL and F methods for both oligozoospermic (0.51 +/- 0.14 vs 0.19 +/- 0.05; p < 0.05) and normozoospermic samples (9.74 +/- 3.11 to 43 +/- 6.01 vs 0.88 +/- 0.23 to 15.30 +/- 3.12; p < 0.001). The P-separated postlayer had higher curvilinear velocities than the DL, F, and prelayered P methods for oligozoospermic samples only (71 +/- 5.13 microns/s vs 53 +/- 3.67 to 59 +/- 2.72 microns/s; p < 0.05). Mean amplitude of lateral head displacement values were significantly different for postlayered P-treated sperm compared with DL, F, and prelayered P-treated sperm for normozoospermic samples only (4.25 +/- 0.16 to 4.67 +/- 0.32 vs 3.01 +/- 0.14 to 3.67 +/- 0.19; p < 0.05). Percoll separation without layering may be the best washing method for both normozoospermic and oligozoospermic frozen-thawed sperm, and the treatment of such recovered sperm with a motility-enhancing agent such as pentoxyfylline may yield optimum fertilization rates.