Limited Utility of a Test‐Yolk Buffer Semen Extender for Preserving Human Semen Parameters for Use in a Diagnostic Setting

BACKGROUND: Identification of a preservation medium that accurately retains semen parameters would be advantageous for men requiring semen analysis by allowing them to produce sperm samples at home rather than on site or even facilitate 'mail order' semen analysis. OBJECTIVES: To evaluate the utility of a commercially available refrigeration medium for preserving human semen parameters for use in a diagnostic setting. MATERIALS AND METHODS: In patients undergoing diagnostic semen analysis, extender was added to the remainder of each ejaculate following initial 'ground truth' testing. Samples were re-assessed to determine effects of incubation time, temperature, volume of extender and speed of addition. RESULTS: Total and progressive motility and vitality declined slowly at 2-5°C, with some motility remaining even after 4 days. The rate of motility and vitality decline was not consistent between samples, with samples outside the reference range being particularly prone to rapid decline. Varying extender conditions showed that even samples with initially good parameters exhibited inconsistent rates of decline in motility and vitality. This was partially ameliorated by incubation at 20-24°C compared to 2-5°C (p < 0.001), while varying the speed of extender addition (dropwise vs. rapid) or the ratio of extender to initial sample had no effect. DISCUSSION: Although semen refrigeration medium does allow sperm to retain some motility for several days, the high level of individual patient variability in the rate of decline precludes accurate reconstruction of initial semen parameters from extended samples. However, total sperm count can be accurately measured. CONCLUSIONS: There are many commercially available kits for semen analysis; however, the reliability of the results is questionable. Semen extenders could potentially be used for triage for samples within the reference range but where measurements from extended samples fall outside reference ranges, confirmation must be obtained from a fresh sample assayed according to WHO guidelines before any diagnosis can be made. TRIAL REGISTRATION: A Study Registration Number is not required as this was not a clinical trial.