Is transrectal ultrasonography a reliable diagnostic approach in ejaculatory duct sub-obstruction?

We studied the diagnostic predictive power of transrectal ultrasonography (TRUS) coupled with semen volume in cases of distal seminal tract sub-obstruction. As a gold standard for diagnosis we used seminal tract washout (STW). Non-azoospermic subjects (n = 112) were submitted to transrectal ultrasonography because of suspected excretory infertility or other andrological pathologies, before performing STW. STW indicated ejaculatory duct sub-obstruction in 36.6% of the patients. Seminal vesicle enlargement (anterior-posterior diameter > or = 15 mm) and seminal vesicle roundish anechoic areas (stasis) were the ultrasonographic anomalies more often associated with ejaculatory duct sub-obstruction. Stepwise logistic regression (SLR) analysis revealed that the ultrasonographic evidence of stasis was highly diagnostic only in the presence of a low semen volume (< or = 1.5 ml) and that ejaculatory duct sub-obstructions may be present but with no evidence of ultrasonographic anomalies. Therefore, TRUS is a useful approach for the treatment of suspected ejaculatory duct sub-obstruction, but is not a reliable diagnostic tool and, before performing transurethral surgery, STW should be mandatory.