The evaluation of WBCs in EPS is recommended for classifying patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) but no agreement has been reached on the optimal method. We sought to determine the relationship between the expressed prostatic secretions (EPS) leukocyte (WBC) count per high-power field (evaluated by a more quantitative wet mount method and the traditional gram-stained smear method used in clinical microbiology laboratories) and the EPS WBC concentration to determine whether quantitative methods are necessary for accurate patient classification.

EPS collected from 94 patients with CP/CPPS were evaluated by gram-stained smear, a standardized wet mount, and a hemocytometer method.

The gram-stained smear detected EPS WBCs in 21 (22%) of 94 subjects compared with 78 (83%) by the standardized wet mount and 57 (60%) by the hemocytometer method. The gram-stained EPS WBC count correlated poorly with the WBC concentration by hemocytometer (R² = 0.051, P = 0.03). Although the standardized EPS WBC count correlated better with the concentration by hemocytometer, the correlation coefficient remained low (R² = 0.244, P <0.0001).

The standardized wet mount proved superior to the gram-stained smear, but both methods lacked precision. Quantitative determination of the EPS WBC concentration by a counting chamber method proved to be the superior evaluation for research studies of CP/CPPS.