This was a young adult male with complaint of small swelling in the left side of neck and mild dysphagia. On Color Doppler examination of the vessels of the neck, the right side showed normal diameter and flow in the right internal jugular vein and common carotid artery (see image on top left). However the left jugular vein showed a fusiform dilatation of the lower part of the vessel (close to its origin, ie: the proximal portion). Here, the vessel measured almost 12 to 14 mm. in diameter at rest. On deep inspiration and Valsalva maneuver, the rise in intrathoracic pressure resulted in diameter of the Internal jugular vein measuring 15 to 17 mm. (see image at bottom left). Compared to the the IJV on the right side the left IJV (internal jugular vein) also showed marked turbulence of flow both on Color Doppler imaging (see images on bottom left) and spectral Doppler waveform. The ultrasound/ Color Doppler images/ findings suggest Ectasia of the left Internal Jugular vein.
Reference: http://www.jultrasoundmed.org/cgi/reprint/18/6/411.pdf (free article and images).