Human semen hyperviscosity: prevalence, pathogenesis and therapeutic aspects

The aims of this study were (a) to determine the prevalence of subjects with semen hyperviscosity (SHV) in a large population of male partners of subfertile couples; (b) to identify any correlation between SHV and infections or inflammation of the genital tract; (c) to assess the effects of therapeutic approaches for treating SHV; and (d) to assess sperm kinetic parameters after successful treatment of SHV. A retrospective study of 1 833 male partners of subfertile couples was conducted. Next, clinical, seminal, bacteriological and ultrasound studies involving 52 subjects suffering from SHV were performed, and the SHV was classified as being mild (length of thread > 2 cm and <= 4 cm), moderate (> 4 cm and <= 6 cm) or severe (> 6 cm). The prevalence of SHV was observed in 26.2% (480) of the subjects, with 13.2% suffering from mild, 6.6% from moderate and 6.4% from severe SHV. Treatment was completely successful in only 27 subjects (52.0%), primarily in those who had mild basal SHV with a positive semen culture. In these subjects, progressive motility percentage, straight line velocity and linearity were significantly higher than pre-treatment levels. SHV is often found in subjects with subfertility. Pathogenesis was strictly related to infective/inflammatory factors in only 48.0% of cases; therefore, it is possible that biochemical, enzymatic or genetic factors have a role in this condition.