Changes in Semen Volume Following Vasectomy: A Retrospective Case-Control Analysis

Vasectomy is the most common non-diagnostic procedure performed by urologists and the only permanent form of sterilization routinely offered to men. Though vasal fluid has been estimated to represent less than 10% of seminal volume, studies describing the effect of vasectomy on semen volume remain limited.

To describe the effect of vasectomy on semen volume compared to controls independent of changes with time/aging.

Men undergoing vasectomy between January 2015 and December 2024, who underwent a pre-vasectomy semen analysis (SA) with volume ≥ 1.5 mL and sperm concentration ≥ 15.0 M/mL, and post-vasectomy SA, were identified and included in this single-center retrospective case-control study. Non-vasectomized men with normal semen parameters and two SAs were identified as controls. Cases were matched to controls in a 1:2 ratio regarding patient age at the time of initial SA.

A TOTAL OF: 957 patients were included in the analysis cohort, including 319 vasectomized men and 638 controls. Mean age (33.3 ± 5.1 vs. 33.4 ± 5.0 years, p = 0.80) and sperm concentration on initial SA (69.2 ± 50.5 vs. 75.5 ± 54.7 M/mL, p = 0.08) did not differ between cases and controls, nor did mean volume on initial (3.51 ± 1.51 vs. 3.51 ± 1.51 mL, p = 0.98) or subsequent SA (3.07 ± 1.42 vs. 3.19 ± 1.60 mL, p = 0.22). Semen volume decreased slightly in both groups between measurements (cases: -0.44 mL; controls: -0.32 mL; both p < 0.0001), but the between-group difference was not statistically significant (p = 0.19). Vasectomy status was not associated with volume change in the univariate (β = 0.06 mL, p = 0.19) or multivariable models (β = 0.04 mL, p = 0.50) adjusted for time between SAs. A sensitivity analysis among matched groups from whom initial and subsequent SA volumes ≥1.5 mL echoed these findings.

Vasectomy does not result in a significant change in semen volume when SA parameters are compared between cases and controls. Patients should be counseled that vasectomy itself does not change semen volume, but that volume might subtly decrease with aging.