Combination of direct swim-up technique and discontinuous Percoll gradient centrifugation for sperm preparation of oligoasthenozoospermic samples

Sperm recovery for assisted reproduction in oligoasthenozoospermic patients is not satisfying either by the swim-up technique or by Percoll gradient centrifugation, and no single technique is constantly preferred. The design of this study was to evaluate the effects of combining the two methods on improving the efficacy of sperm preparation in these poor samples. For each semen sample, 1 mL was treated with a combination method, which used direct swim-up technique to recover motile sperm swimming to the supernatant, and then the residual semen was subjected to two-layer discontinuous Percoll gradient procedure for further recovery of motile sperm. Another 1 mL was prepared with two-layer discontinuous Percoll gradient centrifugation alone for comparison. Parameters measured included sperm concentration, number of progressively motile sperm, percentage of progressive motility, percentage of motile sperm recovery, amount of debris, percentage of normal forms according to Kruger's strict criteria, and motion characteristics of sperm using computer-aided motility analysis. The results of 30 oligoasthenozoospermic samples demonstrated that the combination method achieved a significantly greater recovery of motile sperm than the two-layer discontinuous Percoll gradient centrifugation did (43.2 ± 19.7% vs. 32.2 ± 14.3%, p < .05). The percentage of progressive motility was higher in the samples of the combination method than in those of Percoll gradient centrifugation alone, but the difference was not significant (63.7 ± 21.8% vs. 58.7 ± 20.1%). The debris of semen was removed equally well by both methods. The percentage of normal forms as well as motion characteristics, including curvilinear velocity, straight-line velocity, mean amplitude of lateral head displacement and linearity, were similar in the samples treated by these two procedures. The combination of the direct swim-up technique and discontinuous Percoll gradient centrifugation combines the advantages of each procedure and results in greater recovery of motile sperm in oligoasthenozoospermic samples.