Experience with external quality control in spermatology.

Results are presented from participation in an external quality control (EQC) programme for semen analysis (UK NEQAS). Formalin-fixed semen samples and videotapes of motile spermatozoa were distributed four times a year over a 3-4 year period. Over the entire period there was close agreement for sperm concentration with, initially, the average of values from the other groups participating in the scheme, and later, values designated as reference values obtained from six laboratories of several chosen that consistently agreed with each other. The initial underestimation of the percentage of normal forms was abolished at the time of change in derivation of designated values and this largely eliminated the difference to establish closer agreement with the designated values. A consistent bias in the assessment of different categories of progressive sperm motility appeared to be resolved by a conscious decision to consider most spermatozoa as grade b and the exceptions as grade a, rather than the converse. Feedback of results to the technicians of the laboratory participating in an external quality control programme leads to reappraisal of subjective evaluation and to harmonization of results between laboratories.