Schematic representation of leg veins as discussed in this review. 1, External iliac vein; 2, common femoral vein; 3, greater saphenous vein; 4, profound femoral vein; 5, (superficial) femoral vein; 6, popliteal vein; 7, anterior tibial confluent segment; 8, posterior tibial confluent segment; 9, peroneal confluent segment; 10, anterior tibial veins; 11, posterior tibial veins; 12, peroneal veins; 13, gastrocnemius muscle veins (medial head); 14, soleus muscle veins. (From Palareti G, Schellong S. Isolated distal DVT: what we know and what we are doing. J Thromb Haemost. 2012;10:11-19)