Lower Limb Venous Duplex Ultrasound- Varicose Vein Assessment

Veins in the legs consist of deep veins lying adjacent to arteries and superficial veins with perforating veins and junctions between the two. Venous blood is normally directed from the superficial veins into the deep veins with all normal venous flow directed back to the heart via the deep veins. One way valves within the veins are situated throughout the deep and superficial veins of the leg. These valves are designed to prevent gravity assisted retrograde flow (or reverse flow away from the heart and back down the leg) within the veins. When these valves malfunction they allow this retrograde flow within the vein. As more valves become damaged the veins come under greater pressure and the veins begin to dilate.

When this valvular malfunction occurs in the superficial veins of the leg, the greater saphenous vein and the smaller saphenous vein, these veins became dilated and tortuous and are described as varicose veins. When the deep vein valves malfunction this results in deep venous reflux, which can be a secondary cause of the superficial varicose veins.

Symptoms of venous incompetence can be dilated tortuous superficial veins, swelling, feelings of heaviness and aching in the leg and in severe cases skin health changes in the lower leg or even ulceration.

Varicose veins are strongly associated with family history, gender and pregnancy and occupation.


The patient will need to have the leg being examined exposed from the groin to the foot. They should wear loose fitting clothes or be prepared to remove the outer garments of the lower extremity.  Complete privacy is assured.

The patient is examined in a standing position or a sitting position with the legs dependant. This is necessary in order to assess the presence of valvular insufficiency against the effects of gravity. The study is non-invasive and does not involve any needles. Gel is applied to the skin and the ultrasound probe is run up and down the leg following the veins. The deep and superficial veins are assessed with B-mode and Doppler to assess patency and to determine the direction of the blood flow. The sonographer will be required to squeeze the patient’s calf quite regularly to identify areas of valvular incompetence. If the valve is incompetent blood flow will be seen flowing back down the vein (retrograde flow) after the calf has been squeezed. For large or swollen legs the probe will have to be pushed quite firmly to assess the deeper veins.



A comprehensive examination of all the deep and superficial veins of one leg may take up to 30 minutes. Both legs can be examined in the one sitting but often it is preferable to do them one at a time.


The veins are assessed for patency by demonstrating if they are compressible and free of thrombus. Venous incompetence is identified by the demonstration of reversal of blood flow (retrograde flow) within the vein, towards the foot following calf compression. The length of time of the period of retrograde flow can be measured and the exact point and extent of incompetent within the vein identified. The diameters of the incompetent superficial vein and course of this vein are recorded. This information is used by the treating Vascular Surgeon when the patient is being considered for treatment.