Sensitivity and specificity of ultrasonography in predicting etiology of azoospermia

To determine the sensitivity and specificity of different ultrasound (US) modalities in predicting an obstructive vs a nonobstructive etiology of azoospermia.

A total of 268 azoospermic men with available histopathologic slides were separated into obstructive (n = 104) and nonobstructive (n = 164) groups. Scrotal US studies, including color Doppler and transrectal US examinations, were performed in all patients and compared with the testicular biopsy results as the reference standard.

We found that a decreased testicular volume and intra- and extratesticular varicocele were the most common abnormalities detected using scrotal US in those with nonobstructive azoospermia. In contrast, epididymitis, spermatocele, and duct ectasia were the most common findings in those with obstructive azoospermia. The sensitivity and specificity of scrotal US in detecting nonobstructive azoospermia was 75% and 72%, respectively, and for detecting obstructive azoospermia was 29.8% and 87%, respectively. Prostatic midline cysts, ejaculatory duct calcification, dilated seminal vesicle, and/or vassal ampullae were the most common abnormalities detected using transrectal US for obstructive azoospermia. The sensitivity and specificity of transrectal US in detecting obstructive etiology was 45% and 83%, respectively, and for functional etiology was 39% and 88%, respectively.

Scrotal US was more sensitive in detecting functional azoospermia and more specific in detecting obstructive azoospermia. However, transrectal US was more sensitive in detecting obstructive azoospermia and more specific in detecting functional azoospermia. Both tests had greater specificity than sensitivity for obstructive azoospermia, indicating that US has the ability to exclude more than to diagnose cases of obstructive azoospermia. However, US is unlikely to completely replace testicular biopsy.