Normal valves are almost imperceptible: gossamer structures that are not easily visible. Abnormal valves are more easily seen. They are characterized by irregular thickening, poor mobility and bulging cusps. Thickening may be small foci of echogenic spots measuring less than a millimeter or longer areas of thickening. These are highly echogenic. These thickened areas may form a circular or oval circumference. The circumference may progressively decrease as the transducer is moved down the vein toward the chest. The valve appears to sway to and fro. One sees that the edges of these valves move little and never extend to the lateral walls of the vein. Uncommonly the valve may be seen en face at one level. On the longitudinal view, the lumen may be narrow and there may be two parallel signals (the “double echo" sign) that represent echoes off the valve and off the outer wall of the vein.
