Internal Jugular Vein Phlebectasia:

The above ultrasound/ Doppler images show a typical ectasia of the Rt. IJV in a young child. The diameter of the Rt. internal jugular vein is seen to increase from 8mm. (at rest) to almost 23mm. (on Valsalva). Images are courtesy of Ravi Kadasne, MD, UAE.

http://www.ultrasound-images.com/vascular.htm