High-resolution sonography of the normal extrapelvic vas deferens.

OBJECTIVE The purpose of this study was to determine the reliability of sonographic visualization of the normal extrapelvic vas deferens and to analyze its appearance and dimensions. METHODS Scans of the scrotum and spermatic cords were obtained in 25 fertile volunteers. Identification of the vas deferens was attempted bilaterally in the scrotal, suprascrotal, and prepubic segments in all volunteers. When possible, the total thickness and the diameter of the lumen were measured. Visualization and dimensions were correlated with the body mass index (BMI) and abstinence interval. RESULTS All segments of the vas deferens were identified bilaterally in all volunteers. In all cases, it appeared as an anechoic or very hypoechoic tubular structure that was noncompressible and contained no detectable blood flow. It was convoluted inferiorly and became straight as it progressed from the scrotum to the suprascrotal and prepubic segments. The lumen was seen in the suprascrotal segment in all of the volunteers except the one with the highest BMI. The total thickness of the vas ranged from 1.5 to 2.7 mm (mean, 1.89 mm). The lumen of the vas ranged from 0.2 to 0.7 mm (mean, 0.43 mm). There was no correlation between the luminal diameter and the abstinence interval. CONCLUSIONS The extrapelvic portion of the vas deferens is reliably visualized sonographically. Its appearance is characteristic and reproducible. The lumen can be measured in almost all cases.