Clinical significance of sperm DNA damage threshold value in the assessment of male infertility.

Sperm DNA integrity is a prerequisite for normal spermatozoal function. The aim of the study was to evaluate the role of sperm chromatin damage, its cut-off level and its effect on sperm parameters in men with idiopathic infertility by analyzing 100 idiopathic infertile men and 50 fertile controls. Semen samples were analyzed as per WHO 1999 guidelines and sperm chromatin structure assay (SCSA) was applied to measure DNA fragmentation index (DFI) in sperm. The mean DFI of infertile men (35.75) was significantly (P < .0001) higher as compared to controls (26.22). The threshold level of 30.28% was obtained as cut-off value to discriminate infertile men from fertile controls. Sperm count, forward motility, and normal morphology found to be negatively associated with DFI in overall study subjects. Infertile men with severe oligozoospermia had higher mean DFI (40.01 ± 11.31) than infertile men with oligozoospermia (35.11 ± 10.05) and normal sperm count (33.99 ± 9.96). Moreover 64% of infertile men have DFI > 30 against 6% of fertile controls (P < .0001). Higher sperm DNA fragmentation may be the underlying cause for poor semen quality in idiopathic infertile men and the threshold value of 30.28% is a clear discriminator to distinguish infertile men from fertile men of Indian population. Thus, DFI is a good prognostic marker as cases with higher sperm DFI may have poor success rate even after assisted conception and may experience recurrent pregnancy loss (RPL) and should be counseled accordingly.