OBJECTIVETo investigate the influence of different methods of semen preservation and processing on sperm DNA integrity.

METHODSWe collected semen samples from 100 normozoospermic male volunteers and, following homogeneous mixing, preserved them by means of snap freezing, slow freezing, or at the room temperature for 4 and 24 hours. Meanwhile we processed the semen by washing, swim-up, and density gradient centrifugation (DGC). Then we obtained the sperm DNA fragmentation index (DFI) by sperm chromatin dispersion test and measured total sperm motility and DFI after cultured for 24 hours following processing.

RESULTSThe sperm DFIs after 4 hours of preservation by snap freezing, slow freezing, and at the room temperature were (27.3 ± 6.4)%, (26.9 ± 6.1)%, and (24.7 ± 6.8)%, respectively, and that after preserved at the room temperature for 24 hours was (35.6 ± 9.0)%, with statistically significant differences between the first three and the 24-hour room temperature preservation groups (P < 0.05) but not among the former three groups (P > 0.05). The sperm DFI was significantly higher in the samples processed by washing ([13.7 ± 2.0]%) than in those processed by swim-up ([9.1 ± 1.3]%) and DGC ([8.0 ± 2.5]%) (P < 0.05), and it was the lowest in the DGC group after 24-hour culture ([11.5 ± 4.2]%) as compared with the other groups (P < 0.05).

CONCLUSIONSperm DNA integrity is influenced by different semen preservation conditions and processing methods.