Duplex ultrasound in the assessment of lower extremity venous insufficiency

Characteristics of lower extremity veinsNormal deep and superficial veins of the lower extremity should meet the following criteria: ■ Thin, smooth walls.■ Complete compressibility.■ Spontaneity: Flow observed at quiescence.This may be difficult to observe in small vessels of the calf.■ Consistent color fill: Absence of color filling defects.■ Smooth flow contour: No flow disturbance.■ Presence of flow disturbance can signal irregularity of venous wall or thin fibrinous strands which can be overlooked on 2D examination.■ Phasicity: Respiratory variation.Fall in venous flow velocity with inspiration, rise with expiration.