Swelling and pain in one of your legs, skin that looks red or discolored, and feels warm-- these symptoms can be caused by a blood clot in a vein deep inside your body, usually in one of your legs.

Interv Cardiol. 2012;4(5):527-536. The venous anatomy of the lower leg is made up of two axial systems, a superficial and a deep venous system. The superficial system lies above the muscle fascia ...