Seminal hyperviscosity is associated with poor sperm quality and function.

Purpose: Male infertility affects many couples worldwide. Seminal hyperviscosity (SHV) is increasingly recognized as a contributor to male infertility by impairing sperm movement. However, the precise mechanisms by which SHV affects sperm parameters and functions remain unclear.

Methods: This is a retrospective study. We evaluated the prevalence of subjects with SHV in a large population (including 55,733 semen samples) referring to the Department of Andrology, West China Second University Hospital, as well as the relationship between SHV and sperm quality, DNA damage, Acrosome function, mitochondria function, and seminal plasma composition.

Results: SHV was identified in 12.4% of samples (mild: 7.7%, moderate: 4.1%, severe: 0.6%), with severity correlating to poorer semen parameters, including reduced volume, total sperm count, progressive motility (PR), viability, and normal morphology (all p < 0.05). Notably, SHV samples exhibited impaired acrosomal function and lower mitochondrial membrane potential (all p < 0.05), despite paradoxically lower DNA fragmentation indices (DFI) in mild/moderate cases. Severe SHV showed elevated high DNA stainability (HDS) and chromatin condensation anomalies (p < 0.05). Seminal plasma analysis revealed higher rates of abnormal fructose levels in SHV groups, suggesting seminal vesicle dysfunction as a potential etiology.

Conclusion: These findings highlight SHV's multifaceted detrimental effects on sperm functionality beyond conventional motility metrics, emphasizing its clinical relevance in fertility assessments. All these results remind that clinicians should pay more attention to the index of semen viscosity. In addition, standardized viscosity evaluation protocols and targeted interventions for SHV-related glandular deficiencies are warranted to improve diagnostic accuracy and treatment outcomes.