Normal and variant appearances of the adult epididymis and vas deferens on high-resolution sonography

To describe the appearance, anatomic position, and size of the normal adult epididymis and vas deferens using high-resolution sonography.

The sonographic appearance, anatomic position, and size of the epididymal head (EH), epididymal body (EB), epididymo-deferential loop (EDL), and vas deferens (VD) were evaluated in 112 consecutive infertile men (infertile group), and the data were compared with those from 84 consecutive men without history of infertility (reference group).

Compared with the testis, the EH was isoechoic, the EB hypoechoic, and the VD anechoic. In 88.4% of cases in the infertile group and 97.6% of cases in the reference group, the EH was located above the upper pole of the testis, with the EB lateral to the testis and the EDL below the lower pole of the testis. In 9% of cases in the infertile group and 6% of cases in the reference group, the EB was located posterior to the body of the testis, with the EDL inverted and the VD anterior to the ET. In 11.6% of cases in the infertile group and 2.4% of cases in the reference group, the epididymis was inverted, with the EH located below the lower pole of the testis. The mean (+/-SD) normal sizes were as follows: EH, 7.6 +/- 1.6 mm; EB, 3.2 +/- 0.8 mm; EDL, 7.7 +/- 1.3 mm; VD, 1.9 +/- 0.2 mm. No statistically significant differences in size were found between the 2 groups.

We describe the normal and variant appearance, position, and size of the adult epididymis and VD on high-resolution sonography.