Does ultrasound check all the veins and branches in the leg or just the most common veins where problems arise?

Large deep ones: The ultrasound for clot checks the big/ deep veins in the legs not all the veins. And clots seen below the level of the knee in the deep veins not usually associated with significant problems and are not usually treated with blood thinners. Hope this helps. Best of luck. Dr R

Large veins: The large veins are the usual site of deep venous thrombosis and these are the veins that are checked by ultrasound