Swim-up method is superior to density gradient centrifugation for preserving sperm DNA integrity during sperm processing

Purpose: This study aimed to evaluate the effects of swim-up and density gradient centrifugation methods on sperm DNA fragmentation. Methods: Nineteen normozoospermic patient samples with >= 100 x 106 motile sperms were included in this study. Sperm DNA fragmentation, progressive motility, and progressive motile sperm number were measured before and after the swim-up method or density gradient centrifugation. Results: Sperm DNA fragmentation was not statistically different between swim-up-(14.4 +/- 2.1%, p = 0.32) and density gradient centrifugation-processed (25.0 +/- 3.0%, p = 0.20) and unprocessed semen samples (19.2 +/- 1.9%). Sperm DNA fragmentation was significantly lower in swim-up-than in density gradient centrifugation-processed samples (p < 0.05). Sperm progressive motility was significantly higher (p < 0.05) in swim-up-(92.9 +/- 1.0%) and density gradient centrifugation-processed (81.3 +/- 2.0%) samples, with the former being higher, than in unprocessed semen samples (53.1 +/- 3.7%). The recovery rate of progressive motile sperms was significantly lower in swim-up-(9.7 +/- 1.4%) than in density gradient centrifugation-processed samples (17.2 +/- 1.8%, p < 0.05). Conclusions: The swim-up method is superior to density gradient centrifugation, evidenced by less sperm DNA fragmentation and higher sperm progressive motility. The recovery rate of progressive motile sperms was better after density gradient centrifugation than after swim-up.