Increased seminal microplastic burden in men with varicocele: a controlled clinical study

Microplastics (MPs) have recently been identified in several human tissues, including semen, and growing evidence suggests a potential detrimental impact on male reproductive function. Varicocele, a prevalent cause of male infertility, is associated with oxidative stress, impaired testicular microcirculation, and disruption of the blood-testis barrier, mechanisms that may facilitate MP accumulation in seminal fluid. However, no study to date has compared seminal MP burden between men with and without varicocele.

In this prospective case-control study, 50 men with clinically confirmed Grade II-III varicocele and 48 age-matched controls were enrolled. Semen samples were analyzed according to WHO 2021 guidelines. Microplastics were isolated using KOH digestion, followed by vacuum filtration and classified via light microscopy based on morphology and size (≥ 30 µm). MP concentration was expressed as particles/mL. Correlations and multivariate logistic regression were used to assess associations with semen quality.

Men with varicocele exhibited significantly higher seminal MP load compared with controls (median 8 [IQR 4-14] vs. 4 [IQR 2-8] particles/mL, p = 0.001). MPs were detected in 84% of varicocele samples versus 62.5% of controls. Fiber-type particles predominated in both groups. MP burden showed significant negative correlations with sperm concentration (rho = - 0.32, p = 0.002), progressive motility (rho = - 0.39, p < 0.001), and normal morphology (rho = - 0.28, p = 0.007). In multivariate analysis, both varicocele (OR 2.4, p = 0.032) and MP load (OR 1.8, p = 0.019) independently predicted low progressive motility.

Seminal microplastic burden is significantly elevated in men with varicocele and independently associated with impaired sperm quality. These findings suggest that varicocele may potentiate the reproductive toxicity of environmental microplastics. Larger studies including polymer-specific analyses are warranted.