Within-subject variability of human semen in regard to sperm count, volume, total number of spermatozoa and length of abstinence

Abstract

The within-subject variability of the semen sperm count (n), volume (v) and the total number of spermatozoa (N) was studied on 220 ejaculates from 36 normal subjects after an abstinence of 7 days or less. For each of the 3 variables, the within-subject SD, .sigma., was practically proportional to the mean, .mu.; the common value of the coefficient of variation .sigma./.mu. for all subjects was very high: 0.39 for n, 0.28 for v and 0.55 for N. The 95% confidence intervals based on a single ejaculate were asymmetrical and very large, the lower and upper limits being, respectively, 0.5 .times. n and 2.3 .times. n; 0.7 .times. v and 1.8 .times. v; 0.4 .times. N and 2.9 .times. N. The 3 semen characteristics for a given subject were highly correlated with the length of abstinence; for an increase in abstinence of 1 day there were mean increments of 13 .times. 106/ml for n, 0.4 ml for v and 87 .times. 106 for N.