Objective To determine the level of malondialdehyde (MDA), an indirect indicator of lipid peroxidation‐induced injury by reactive oxygen species, in testicular biopsy specimens from infertile patients with and without varicocele.

Patients and methods Levels of MDA were measured in the testicular biopsy specimens from 25 infertile men (15 with varicocele, mean age 30.0 years, sd 5.7, range 23–45, and 10 without, mean age 28.7 years, sd 4.2, range 21–34). All patients were evaluated by a detailed history, physical examination, semen analysis (at least twice), serum follicle‐stimulating hormone and free testosterone levels, testicular biopsy and contact imprint. Scrotal colour Doppler ultrasonography was used to confirm suspected varicocele. The level of MDA in testicular biopsy specimens was measured using the thiobarbituric acid test and the results expressed per unit tissue weight.

Results As a causal factor for infertility, varicocele was identified in 15 men (60%), testicular failure in four (16%), idiopathic infertility in four (16%) and obstruction in two (8%). Of the 15 patients with varicocele, eight had bilateral varicocele and it was subclinical in three; the varicocele was grade I in four, grade II in six and grade III in two. The mean ( sd) MDA level in the men with a subclinical varicocele was 15.7 (3.1) pmol/mg tissue, while in those with grade I–III varicocele it was 32.9 (12.25), 37.1 (12.25) and 86.9 (2.89) pmol/mg tissue, respectively. The levels in patients with grade III varicocele were significantly greater than in the other groups (P < 0.05). The mean MDA level in patients with or without varicocele was 38.3 (22.92) and 33.5 (18.93) pmol/mg tissue, respectively (P > 0.05).

Conclusion These results suggest that increasing levels of MDA are associated with higher grades of varicocele and support a possible rationale for controlled trials in infertile men with varicocele.