Feasibility study for the centralized measurement of sperm concentration.

Despite several efforts to standardize methods of semen analysis, sperm count is known to be subject to large interlaboratory differences. This is especially a problem in multicentre clinical trial settings and protocols for the preparation of semen for centralized assessment of sperm concentration are suggested here. The stability of semen has been tested after fixation with formalin at different dilutions and at different temperatures for different sperm concentrations. Sperm concentrations in formalin-fixed semen (at dilutions 1 + 0.5 to 1 + 19) were stable (<20% difference from original) at all concentrations (0.1 x 10(6)/mL to 100 x 10(6)/mL) for at least 5 days at room temperature and 4 degrees C. Prolonged stability up to 5 weeks at 4 degrees C was demonstrated for the lower dilutions (1 + 0.5 and 1 + 1). Freezing of fixed semen samples was unacceptable. These results illustrate that centralized assessment of sperm concentrations is feasible.