 Normal blood flow is anterograde ( going to the heart ) , and from superficial to deep veins via perforator veins . However , there are two exceptions : firstly , the great saphenous vein ( GSV ) collaterals , ( the veins that run parallel ) , drain the abdominal wall and have a flow from top to bottom so that when an examiner tests the sapheno @-@ femoral junction , a false positive diagnosis might be made ; secondly , in the flow from the sole of the foot venous network around 10 % drains to the dorsal venous arch of the foot , going therefore against the norm , from deep to superficial veins . 
