Clinical use of the turbidimetric analysis of sperm motility: comparison with visual techniques.

Semen characteristics of men with apparent fertility problems are analyzed primarily by routine visual techniques. Although these techniques provide quantitative information regarding the sperm count, they give only qualitative information about sperm motility. We compared visual microscopic ratings of sperm motility (based on an arbitrary scale of 0 to 4 in half-unit steps) with turbidimetric spectrophotometric analyses for 100 patients from our male fertility clinic. In the turbidimetric method, semen is layered on the bottom of the cuvette filled with Lopata's medium, and motility is quantitated as the rate of change in optical density as the sperm swim upward into the light path. The visual sperm motility rating did not correlate with the turbidimetric rating. Whereas most of the patients had visual ratings of 2.5 to 3.0 (indicating normal motility), the majority had turbidimetric motility factors that were well below the average motility factor for a control group. On the basis of these studies we believe that the turbidimetric analysis of sperm motility is a much more accurate measure of sperm motility than is visual microscopic analysis. Its major advantages are that (1) it provides a quantitative measure of sperm motility; (2) it does not rely on arbitrary rating by an individual; and (3) the sperm must perform work in order to be measured (i.e., leave the semen and swim upward into the light path).