Agreement and internal quality assurance of the Neubauer hemocytometer and Makler chamber for human sperm concentration determination.

Objective: The Neubauer hemocytometer, as well as the Makler chamber, are devices commonly used in andrology laboratories. The present study aimed to verify if both methods yield comparable results, and whether they can be used interchangeably to determine sperm concentration.

Methods: Sperm and latex beads concentration measurements were performed with the Neubauer hemocytometer and the Makler chamber. Fixed and proportional biases were estimated, and the method agreement was determined by assessing sperm concentration results with the Bland and Altman plot. The Coefficient of Variation (CV) and relative bias were calculated as an index of precision and accuracy, respectively, by measuring latex beads target concentrations in both chambers.

Results: The Makler chamber systematically overestimated the Neubauer hemocytometer concentration measurements by a mean of -7.99%, with limits of agreement (LOA) between -41% to 25.61% (p<0.001). The fixed bias was found for concentration values inferior to 40 x 106/ml range (p<0.001), but not higher concentration results (p>0.05). Measurements with the Neubauer hemocytometer showed the greatest consistency in the study with the CV ranging from 3.01% to 6.67%; while the CV with the Makler chamber ranged from 8.46% to 25.64%. The relative bias for the Neubauer hemocytometer determinations varied from 0.12% to 8.40%, while for the Makler chamber varied from 7.6% to an overestimation of 38.0%.

Conclusions: Measurements made with the Makler chamber demonstrated more variability and a higher degree of overestimation. The Makler chamber is a poor substitute to the Neubauer hemocytometer for evaluation of oligozoospermic samples, although both chambers render similar results for highly concentrated samples.