Contribution of investigations to the diagnosis of bilateral vas aplasia

BACKGROUND: Bilaterally absent vas deferens is a surgically uncorrectable cause of male infertility. It is usually diagnosed clinically. We evaluate the role of semen analysis and radiological imaging in providing objective evidence of vas aplasia. METHODS: Twenty consecutive patients with clinically suspected bilateral vas aplasia were enrolled for this prospective study. They were investigated on the basis of an algorithm till corroborative evidence for vas aplasia was obtained. This successively included a semen analysis on at least two occasions, transrectal ultrasonogram (TRUS), pelvic magnetic resonance imaging (MRI) and scrotal exploration. The contribution of each investigation to confirming the diagnosis was evaluated. RESULTS: Seventeen patients (85%) had a low volume ejaculate while all 20 had azoospermia and semen fructose levels below normal. Semen pH was non-acidic in 75% of cases and thus was not contributory to the diagnosis. TRUS and MRI were non-contributory in 30% and 50% of evaluations, respectively. The clinical diagnosis was found to be correct in all patients. CONCLUSIONS: Vas aplasia is a clinical diagnosis. Low volume ejaculate with azoospermia and low or absent semen fructose is sufficient corroborative evidence and no further investigations are required for this diagnosis.