 Attention will be focused on the direction of the blood flow in both of the venous systems , and in the perforator veins , as well as being focused on shunt detection . A shunting of blood from the thigh veins back into the lower leg veins will give a reflux situation . The veins most often found to be incompetent are the saphenous veins and the perforators communicating with the deep veins of the thigh . 
