Elimination of errors induced during a routine human sperm motility analysis

Influence of some variables on the accuracy of sperm motility evaluation was studied by analyzing normal seminal specimens with the aid of the multiple exposure photography (MEP) method. Results of this study demonstrated the existence of variations in sperm motility between view areas of the same sample or between different samples of the same specimen. Variations were found even when the same view area was analyzed intermittently during a short period of time. Motility was practically unaffected when a regular sized drop was kept within the preparation for about 20 min. The light from the microscope neither stimulated nor depressed sperm motility when they were illuminated continuously for that period of time. Percent of motility and sperm velocity was directly related to the thickness of the examined drop when the latter ranged between zero and ten micrometers. According to these findings it is suggested that several view areas from various drops of the same specimen should be analyzed with each view area being inspected several times before motility of that field is assessed. Motility should be evaluated from drops of standard and constant thickness; otherwise major errors in sperm motility assessment are to be expected.