External quality control in the andrology laboratory: an experimental multicenter trial.

An external quality control study for semen analysis was performed involving 10 andrology laboratories in geographically separate locations. For the evaluation of sperm concentration, eight samples with different concentrations, and for the assessment of sperm morphology three slides prepared from different semen samples were distributed. Sperm motility was evaluated in five samples delivered cryopreserved to the participants. The coefficients of variation (CVs) for sperm counts varied with the sperm concentrations showing highest variability for low and lowest for high concentrations (range 23% to 73%). The CV for sperm morphology ranged from 25% for normal heads to 87% for abnormal midpieces. The CV for motility of sperm was 21%. For comparison the mean CVs for internal quality control were as follows: 10% for concentration, 8% for morphology (normal heads), and 8% for motility.