Two wet mount slides should be prepared and examined for sperm motility. Evaluate at least five fields and/or a minimum of 200 spermatozoa on each replicate. The high power objective (400× magnification) should be used. For very low counts, increased numbers of fields may have to be examined, and the total number of sperm may be less than 100.
Calculate the average percentage of each category on each slide and then compare the differences between the two percentages for the most frequent motility grade reported (rapid progressive, slow progressive, non-progressive, or immotile). The table below, provided by WHO 6th edition, may be used to determine if the counts obtained from the replicate slides agree sufficiently. If they are not, two additional replicates should be made from the original specimen, and the motility assessment should be repeated.
Table 1. Acceptable differences (based on 95% confidence interval) between two percentages for a given average, determined from replicate counts of 200 spermatozoa (total 400 counted).
| Average (%) | Acceptable Difference |
| 1 | 2 |
| 2–3 | 3 |
| 4–6 | 4 |
| 7–9 | 5 |
| 10–13 | 6 |
| 14–19 | 7 |
| 20–27 | 8 |
| 28–44 | 9 |
| 45–55 | 10 |
| 56–72 | 9 |
| 73–80 | 8 |
| 81–86 | 7 |
| 87–90 | 6 |
| 91–93 | 5 |
| 94–96 | 4 |
| 97–98 | 3 |
| 99 | 2 |
