In order to evaluate the DVS with the Trendelenburg test, a tourniquet is tied around the upper thigh of the patient's affected leg while the patient is standing. The patient is then asked to lie down and elevate the affected leg.[5] If there is no involvement of the DVS (eg, with a DVT) and the deep veins are patent, the superficial veins will have normal emptying.[5] However, the presence of dilated veins that do not empty with elevation of the affected leg suggests an obstruction of the DVS.[5] However, according to the Clinical Practice Guidelines by the Society for Vascular Surgery and the American Venous Forum, the diagnosis of varicose veins is rarely done using the Trendelenburg test today, especially if duplex scanning or Doppler studies are available.[3] However, in cases in which more advanced scanning is unavailable, the Trendelenburg test may still be valuable.