Immediately following ejaculation, semen is in a gel-like condition. The term coagulation has been used to describe this state. Within 20-30 minutes, semen, through the action of enzymes, becomes liquid. If coagulation does not occur this can be significant in determining the cause of some cases of infertility In the liquid state, semen with normal viscosity can be poured drop by drop into another container and does not appear stringy or clumped. Samples that are hypoviscous can be described as watery with a rating of 0, while hyperviscous samples may be gel-like with a rating of 4. It is important to remember that liquefaction of the sample must take place before viscosity is determined.
A specimen that is more viscous than normal, after liquefaction has taken place, will inhibit the sperm’s motility. In some cases of infertility this is the only abnormality that can be demonstrated. Increased viscosity can be caused by prostatic dysfunction, infection, or the presence of antisperm antibodies.
