Scrotal US for evaluation of infertile men with azoospermia

To evaluate prospectively the accuracy of scrotal ultrasonography (US) in distinguishing obstructive azoospermia from nonobstructive azoospermia in infertile men by using histologic findings as the reference standard.

The institutional review board approved the study, and informed consent was obtained from each patient. Twenty infertile men (mean age, 34.7 years; 40 testes) with azoospermia were evaluated at scrotal US, with an emphasis on the course of the proximal genital duct: mediastinum testis, epididymal head, epididymal body, and epididymal tail. Testicular volumes were calculated by using the formula: length x height x width x 0.71. On the basis of histologic results, azoospermia was divided into two groups (obstructive vs nonobstructive) in all cases except one. Scrotal US findings between obstructive and nonobstructive azoospermia were compared. The Fisher exact and Wilcoxon signed rank sum tests were used to assess differences between both groups.

Of 20 infertile men with azoospermia, 14 were proved to have obstructive azoospermia; the others had nonobstructive azoospermia. According to US findings, epididymal abnormalities in the head, body, and tail were significantly associated with obstructive azoospermia (17 [61%], 18 [64%], and 20 [71%] of 28 testes, respectively; P < .001 for all), while abnormalities of the mediastinum testis between both groups were not significant (P > .05). By taking epididymal abnormalities into account, sensitivity, specificity, and accuracy of scrotal US for differentiation of obstructive from nonobstructive azoospermia were 82.1% (23 of 28 scrota), 100% (12 of 12 scrota), and 87.5% (35 of 40 scrota), respectively. The median testicular volume in obstructive azoospermia was 11.6 mL (range, 7.7-25.8 mL) and that in nonobstructive azoospermia was 8.3 mL (range, 1.2-16.4 mL) (P < .05).

Evaluation of the epididymis and measurement of testicular volume with scrotal US are important in distinguishing obstructive azoospermia from nonobstructive azoospermia in infertile men.