Thrombophlebitis is inflammation of a vein (usually in an extremity, especially one of the legs) that occurs in response to a blood clot in the vessel. When it occurs in a vein near the surface of the skin, it is known as superficial thrombophlebitis, a minor disorder commonly identified by a red, tender vein.
Deep-vein thrombophlebitis (affecting the larger veins farther below the skin's surface) is more serious. It may produce less-pronounced symptoms at first but carries the risks of pulmonary embolism (when the clot detaches from its place of origin and travels to the lung) and chronic venous insufficiency (impaired outflow of blood through the veins), resulting in dermatitis, increased skin pigmentation and swelling.
The causes of thrombophlebitis include:
- Stagnant blood. This is common among bedridden patients (such as heart patients and those who have undergone any type of major or orthopedic surgery, especially of the hip or knee) and healthy persons who sit or lie still for an extended period - for example, on a long trip.
- Blood vessel injury. This could be caused by trauma, intravenous catheters or needles, chemotherapeutic agents, or infectious organisms.
- Conditions that increase the tendency for blood to coagulate, such as a familial deficiency in anti-clotting factors.
- Pregnancy and varicose veinsare associated with a higher risk of superficial thrombophlebitis.
- Deep-vein thrombophlebitis is associated with a number of different cancers.