"Doppler ultrasound can detect the presence and distribution of subcutaneous varicosities. Moreover, it is the method of choice to assess the state of the saphenofemoral junction. Reflux of blood flow at the junction during the Valsalva manoeuvre indicates incompetence. Reflux that lasts for more than 1 second is significant and usually requires surgical intervention. Reflux that lasts 0.5-1 second is insignificant and usually requires conservative management. Incompetent perforators are assessed in the standing position."