IntroductionHigh levels of oxidative stress can explain the presence of high levels of damage in the DNA molecule. The impact of high levels of oxidative stress in 2 clinical circumstances affecting the male germ line has been well established: leukocytospermia and varicocele. ObjectiveTo assess sperm DNA fragmentation in patients diagnosed with leukocytospermic and varicocele. Material and methodsLeukocytospermic and varicocele patients and external controls (donors with proven fertility and patients with undetermined male factor). Unlike in other studies of sperm DNA fragmentation, in this study both the proportion of damaged sperm after using the sperm chromatin dispersion test (Halosperm), and the proportion of degraded sperm in total fragmented (degradation index [DI]) were taken into consideration. ResultsA highly significant increase in sperm DNA fragmentation has been observed in semen samples of patients with varicocele and leukocytospermia. Varicocele patients showed a DI twice as high as that observed in patients with undetermined male factor or in patients with leukocytospermia, and 6 times as high as that observed in the donors. DiscussionThe presence of high levels of oxidative stress could be an acceptable explanation for the high levels of damage observed in the spermatozoa of varicocele patients or with leukocytospermia; the level of sperm degradation is higher in the case of varicocele than those observed in leukocytospermia. ConclusionsSDF levels in patients with leukocytospermia and varicocele are significantly higher than those observed in donors or men with undetermined male factor. The DI in sperm samples from patients with varicocele is the highest of all the samples studied in this analysis. The routine determination of the DI may have a practical value, by guiding the patient towards the potential diagnosis of varicocele, even when this is subclinical.