Venous disease has high prevalence, affecting at least a third of the adult population in Western countries. In patients with venous disease, the venous return is impeded as a result of reflux, obstruction, or the combination of both pathologies. Reflux is the most common pathology found and in the majority of patients is primary. Obstruction can be acute, as in patients with venous thrombosis, or it can be chronic as a result of past thrombosis or extrinsic compression. Acute and chronic obstruction can be found in patients with recurrent thrombosis or extrinsic compression and thrombosis.

The advent of duplex ultrasound has allowed the assessment of the venous anatomy and function in real time (Figure 1). It has several advantages: It has low cost and it is portable, safe, easy to repeat, noninvasive, and the best method to identify reflux and obstruction at the same time. It is also used to guide treatment and assess the results. Complementary to venous duplex ultrasound are physiologic tests such as plethysmography, which may be indicated to gauge the severity of reflux or calf muscle pump function.

Evaluation of Reflux

Superficial Veins

Reflux is most often found in the superficial veins, with the saphenous veins and their tributaries being the most common location. Duplex ultrasound examination to investigate reflux is carried out with the patient in standing position.

First, the great saphenous vein (GSV) should be identified in the groin, lying medial to the common femoral artery. At this level, the GSV unites with the common femoral vein (CFV) to form the saphenofemoral junction (SFJ). Other veins that are parallel to the GSV but located outside the saphenous canal can also be found in the groin but are defined as accessory saphenous veins. Duplication of the saphenous veins is found in less than 3% of patients with cardiovascular disease. Patients who underwent SFJ ligation might still have tributaries connecting to CFV caused by residual veins or neovascularization.

The location of the GSV terminal valve, its competence at the SFJ, and the route of reflux should be traced. The saphenous veins should be tested every 3 to 5 cm for compressibility and reflux, which is defined as abnormal if longer than 500 msec. An automated pneumatic cuff inflation and deflation device is necessary if comparative data (before and after treatment) on the duration of the reflux are obtained.

Diameter measurements of the saphenous trunk are made at several locations. Applicability of diameters and routes of reflux are necessary to plan procedures such as ultrasound-guided endovenous ablation, foam injection, or surgery. In addition, the distance between the saphenous veins and the skin is important to assist in preventing skin damage during endovenous procedures.

The small saphenous vein (SSV) and its tributaries are evaluated thereafter. The SSV is identified in the triangular fascia. It is surrounded by the crural fascia and the gastrocnemius muscle heads. It connects with the popliteal vein, forming the saphenopopliteal junction (SPJ), but also can have a higher termination at several locations. In at least a quarter of the patients there is no SPJ. Identifying connections between the SSV and the vein of Giacomini, the GSV, and the perforators is critical to tailor the treatment of reflux to each patient. Also, the posterior accessory vein (vein of Leonardo), which is a major tributary of the GSV, must be identified in the medial aspect of the calf because it is often connects with the SSV at the calf.

Deep Veins

Isolated primary axial deep vein reflux is rare. Most commonly, deep vein reflux is seen at the saphenous junctions, and it is induced by longstanding superficial vein reflux. Treatment of superficial vein reflux often resolves the deep vein reflux; however, retrograde flow distal to the level of junctions represents true deep vein reflux. Reflux in the femoropopliteal veins is confirmed with reverse flow duration greater than 1000 msec and in the deep calf veins such as the peroneal, posterior tibial, soleal, and gastrocnemius when greater than 500 msec. Axial reflux in deep veins is commonly seen after an episode of thrombosis.

The CFV is the first vein tested having a normal vein phasic flow with normal respiration, cessation of flow with deep inspiration, and flow during manual compression distally. In patients with proximal obstruction, a continuous flow is detected in the CFV, prompting a scan of the iliac veins and inferior vena cava. Subsequently, the full length of the femoral vein and popliteal vein is studied. The popliteal vein is examined above and below the SPJ when this is present in order to differentiate reflux from flow overload of incompetent superficial veins and true deep vein reflux. The anatomic and hemodynamic relationship of the popliteal at the SPJ and gastrocnemius veins should be established. Last, the deep calf veins are also investigated for reflux.

Perforator Veins

The perforator veins are found in the entire length of the lower limb. There are about 150 perforator veins in each lower extremity, of which only about 20 become incompetent in patients with cardiovascular disease. Perforator veins are veins that pierce the deep fascia and connect the superficial veins to the muscular and the deep axial veins. Flow direction, diameter at the fascia defect, and the location of the perforator veins are recorded. An outward flow (from deep to superficial veins) greater than 500 msec is considered abnormal. A perforator vein diameter of greater than 3.5 mm is considered abnormal. Perforator veins in the medial aspect of the leg are most often associated with skin damage and ulceration.

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