Reproducibility and reliability of repeated semen analyses in male partners of subfertile couples

Objective: To determine the precise degree of variability that is represented by the reproducibility and reliability of semen analysis. The general assumption is that semen analyses need to be repeated because of a high degree of within-individual variability. However, the precise degree of variability is not well established in male partners of subfertile couples. Design: Retrospective cohort study. Setting: Two university hospitals in the Netherlands, which routinely perform two semen analyses in the male partner of subfertile couples. Patient(s): Male partners of subfertile couples. Interventions: None. Main Outcome Measure(s): We assessed the test-retest reproducibility, by calculating the coefficient of variation (CV_w) for five semen parameters. The CV_w expresses, on a relative scale, the degree of closeness of repeated measurements taken in the same subject. We also estimated the reliability of these semen parameters, in terms of the intraclass correlation coefficient, which expresses the ratio of the between-subject variability over the total variability. Result(s): We analyzed the data of 5,240 men and found that the CV_w of all semen parameters ranged from 28% to 34%. The intraclass correlation coefficients of these semen parameters were moderate to high: volume: 0.70; concentration: 0.89; motility: 0.58; morphology: 0.60; total motile count: 0.73. Conclusion(s): This study affirmed the presumed large within-subject variability and the limited reproducibility of semen analyses in subfertile men. Whether this degree of variability within men justifies one or more repetitions of the semen analysis in view of consequences for clinical management should be the topic of future studies. Until then it seems reasonable to perform two semen analyses.