External Jugular Vein Distention:The picture above demonstrates a markedly distended right external jugular vein (EJV). This is the result of elevated central venous pressure (CVP). The picture below demonstrates the effect of hepatic pressure on the appearance of the EJV (i.e. vein becomes more engorged).
In practice the EJV is not as reliable in determining CVP as the internal jugular vein(not visualized here) due to the fact that it sometimes has valves and is not in a direct line with the right atrium. Pressure on the liver, however, will have similar impact on the appearance of the IJV as demonstrated above for the EJV. This is referred to as hepatojugular reflux.