Venous incompetence of the lower extremity is a common clinical problem. Duplex ultrasonography is the method of choice to evaluate patients with chronic venous disease as it provides the distribution and extent of reflux, anatomic variations, vein diameter, tortuosity, distance from the skin, luminal obstruction (acute thrombosis and chronic post-thrombotic changes) thus being able to determine the modality and extent of treatment (1). Duplex ultrasono-graphy is more sensitive than descending venography in measuring the degree and distribution of venous reflux and predicting the clinical severity of venous insufficiency (2). Therefore, duplex ultrasound is the standard for assessing venous reflux in the saphenous system as well as non-saphenous system (3,4).

Examples of duplex ultrasonography image and reporting sheet are shown in Fig. 1 and 2. When documenting reflux, examiners should include following information to provide reliable results; the name of the vein segment where the reflux was observed, the reflux time, and the flow direction. First, it is essential to record the name of the vein for which reflux was measured to provide a clear rationale for indications for treatment and for communication with other physicians. Depending on the protocol used for each center, the common femoral vein, proximal to the sapheno-femoral junction, the sapheno-femoral junction, the great saphenous vein from groin to ankle, the femoral vein, the popliteal vein and the small saphenous vein from junction to ankle and its thigh extension as well as perforating veins are interrogated with duplex imaging. When the physical examination suggests non-saphenous origin reflux, popliteal fossa vein, sciatic nerve vein or tibial vein can also be examined. Second, reflux time should be recorded. Retro-grade flow in the lower-extremity veins occurs physio-logically just before valve closure, and pathologically as a result of valve absence or incompetence (5). Duration of physiologic retrograde flow is reported less than 500 ms in 96.7% of the superficial veins and the cut-off value of 500 ms is used to discriminate pathologic reflux from physio-logic retrograde flow (6). By adjusting the sweep speed in Spectral Doppler mode, the start and end of reflux can be displayed on one screen and the exact duration can be measured. Third, flow direction is also documented. It is recommended to measure the reflux with assuring that the Doppler cursor is appropriately aligned with the vessel wall, so that the direction of the flow is clearly documented. In the perforator veins often there is bidirectional flow. Therefore the net outward flow (<500 ms) from the deep to superficial system is considered as a reflux (7). Reflux can be induced by the Valsalva maneuver which is recommended only the groin area when the augmentation test is negative for reflux. Manual compression distal to the examining site produces flow augmentation while sudden release of the compression allows to test valve competency. This can also be done with automated rapid inflation/ deflation cuffs. The latter is more accurate as it provides a standard compression as a before and after study when the effect of different treatments is tested. However, for the presence or absence of reflux the manual testing is as good. In some patients with a lot of edema of severe skin damage the veins in the lower calf and ankle are best tested by applying pressure in the foot or better with active dorsi/plantar flexion.

Figure 1. Duplex ultrasonography image showing significant reflux.

Figure 2. Example of reporting sheet.

Another thing to consider in ensuring accurate examina-tion results is patient position; in a dependent position either by having the patient lying in the reverse Trendelenburg position or in the standing position. Alternatively, for scanning below the knee, the patient may be seated with legs down. It is also recommended to have standard worksheets at each center to provide complete examination results with guaranteed quality.

As duplex ultrasound is important in patients with venous incompetence, the examiner should put forth the best efforts to present reliable test results. The establishment of guidelines reflecting the domestic situation should also be considered.