Computer‐assisted image analysis of sperm concentration in human semen before and after swim‐up separation: comparison with assessment by haemocytometer

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Abstract
Evaluation of male fertility is based predominantly on results from semen analysis and determination of the sperm concentration is one of the main parameters of the analysis. The availability of a fully automated videomicrographic digital image analyser would offer both an objective and rapid method for determination of the sperm concentration. In the present study the sperm concentration in 327 semen samples was determined by haemocytometer according to the World Health Organization guidelines, and also by a computer‐assisted digital image analyser system. Results were classified according to the routine procedure (haemocytometer) before statistical analyses. The computerized measurements caused a shift to the right in the frequency distribution of sperm concentration. Sperm concentrations were more often overestimated significantly (P < 0.001) by the computerized measurements in semen samples with concentrations up to 80.0 × 106/ml. This overestimation seemed to be caused by the presence of particles in seminal plasma that were recognized incorrectly as sperm by the computer program. The computerized digital image analyser gave an average sperm concentration of 2.2 ± 0.6 × 106/ml (mean ± SEM) in 17 azoospermic semen samples while the routine procedure did not detect the presence of sperm cells. After removing the seminal plasma by washing and centrifugation with culture medium, and using the swim‐up procedure to harvest motile sperm, the computerized measurements showed comparable results with the routine procedure for those sperm preparations (n= 44) with sperm concentrations >5.0 × 106/ml. In sperm preparations with concentrations < 5.0 × 106/ml (n= 75) there was still a significant (P < 0.001) overestimation of the sperm concentration. These findings indicate that the CellSoft computer program has to be improved to allow correction for the particles present in seminal plasma which are not sperm. For determination of the sperm concentration in seminal plasma‐free preparations, an effective method to remove these particles is also necessary to obtain reliable results with the present computer‐assisted digital image analyser system.