The clinical value of conventional semen analysis.

The objectives of this study were, firstly, to relate semen variables to treatment independent conception rates by life-table analysis after having accounted for known female factors; secondly, to assess the relationship between the length of involuntary infertility before investigation and the predictive value of semen parameters; and thirdly, to examine the relationship between the type of progressive spermatozoal motility and fertility outcome. Laboratory error in the assessment of semen variables was minimized by using one consistent observer. Seven hundred thirty-nine subjects were recruited to the study over a 34-month period, and a 96.5% follow-up rate was achieved. Where the female partner had regular spontaneous ovulation, no pelvic pathology, and more than 48 months' preceding infertility, the Grade 2 motile sperm density (the concentration of spermatozoa exhibiting slow or sluggish linear or nonlinear motility) was the variable that best predicted fertility outcome (X1(2) = 20.24, P less than 0.0001). Where the Grade 2 motile sperm density was below 5 X 10(6)/ml in the latter group (19%), no conceptions were reported at 32 months' follow-up. Semen variables were not of predictive value where there were fewer than 48 months' infertility before investigation, or where the female partner had ovulatory dysfunction or pelvic pathology.