BACKGROUND: Fellow Post Vasectomy Semen Analysis (PVSA) is a mail-in semen analysis system in the United States. Currently, there are no published results on sperm stability over time comparing data evaluated within hours of collection to re-evaluation over a 10-day period. Reliability of PVSA is important. Here we characterize the changes observed in sperm cellular concentration at low sperm concentrations, reflecting the post-vasectomy state, when using the Fellow PVSA preservation system. The purpose of this study is to evaluate whether any low concentration specimens reduce to zero when evaluated over a 10-day period.
METHODS: Fresh semen samples from consented men enrolled in the IRB-approved Fellow clinical study were used. Samples were diluted from higher concentrations to standard aliquots of 0 sperm, 0.1 M/ml, 1 M/ml) with the addition of the Fellow PVSA preservation solution. 20 replicates of each cellular concentration were created (total N=60) to accurately estimate concentration at each timepoint. Sperm concentration was measured at 2 time points (Day 0 and Day 10). Descriptive statistics and 1-sided t-test were utilized to test the hypothesis that the mean concentration on day 10 is 0.
RESULTS: The PV-low group had a mean concentration of 0 at day zero and 0 at day 10. The PV-medium group had a mean concentration of 0.136 M/ml (SD: 0.026; min: 0.110; max: 0.161) at day 1 to 0.126 M/ml (SD: 0.023; min: 0.103; max: 0.149) at day 10 (no specimen went to zero; p<0.001), while the PV-high group had a mean concentration of 1.400 M/ml (SD: 0.250; min: 1.149; max: 1.650) at day 1 to 1.234 M/ml (SD: 0.092; min: 0.142; max: 1.327) at day 10 (no specimen went to zero; p<0.001).
CONCLUSIONS: For men utilizing the Fellow PVSA preservation system, sperm concentration remains stable from day 0 to at least day 10 after production. This is the first published study comparing a fresh semen analysis evaluated within 4 hours of collection to specimen re-evaluation at 10 days after collection. Urologists can feel confident that results from the Fellow PVSA accurately reflect their immediate fresh post-ejaculatory status. Further larger studies are necessary to confirm this finding.
