What is deep vein thrombosis (DVT)?

A deep vein thrombosis (DVT) is a blood clot in the deep veins, usually of the legs but occasionally in the arms.

The function of the veins (or venous system) in the legs, is to pump blood back from the legs to the heart. Although all of the veins in the legs eventually connect to the pelvic veins, in the legs the veins are separated into two main systems – the superficial and the deep venous systems.

The deep system of veins are those veins that are positioned within the muscles of the lower leg and thigh. The superficial system of veins are those veins that lie outside of the muscle, within the fat and just under the skin. Neither of these systems of veins can be seen in normal people – although in very slim people with virtually no body fat, veins of the superficial venous system might be seen.

Blood in the superficial venous system of the leg drains into the deep veins. This occurs  either by one of the two main junctions, the saphenofemoral junction (SFJ) in the groin and the saphenopopliteal junction (SPJ) behind the knee, or via any of the perforating veins that are found connecting the two systems in the leg.

If for any reason a clot (medically known as a thrombus) is formed in the deep veins, it is called a deep vein thrombosis (DVT).

Next page: The signs and symptoms of a deep vein thrombosis (DVT)

This website was last updated on 11/10/16.