A new method to estimate quantitatively seminal vesicle and prostate gland contributions to ejaculate

Aims: We sought to optimize a quantitative noninvasive method to determine the concentration in their glands of origin of biochemical markers of compartments of the male genital tract as the first step towards validation of a novel method for estimation of drug concentrations in these male genital tract compartments. Methods: Sixty-eight men participated. We compared four collection devices to split ejaculate into fractions. Fractions were assayed for fructose and prostate specific antigen (PSA) as unique markers of the seminal vesicle and prostate, respectively. Seminal vesicle fructose and prostatic PSA were estimated using a linear regression method, based on fructose-PSA axis intercepts, and compared with an older method which solves a simultaneous series of equations. Results: A five-compartment collection device performed best with mean (95% confidence interval) PSA vs. fructose r² of 0.84 (0.71, 0.98, P < 0.001). Using resampling simulations, glandular PSA and fructose estimates were highly variable and often implausible when using only two fractions. Using our method, the prostate contributed 37-44% to the whole ejaculate and the seminal vesicle contributed 55-61%. The novel regression method was highly correlated (r² ≥ 0.98) with older methods. Conclusions: We developed a noninvasive quantitative method of male genital tract biochemical marker estimation using a five-compartment tray to collect three to five ejaculate fractions. Our novel regression method is quantitative and more fully developed than older methods. This noninvasive method for determining glandular marker concentrations should be useful to provide quantitative estimates of drug concentrations in these glands.