Overview of Thrombophlebitis

Thrombophlebitis is inflammation of a vein with one or more blood clots. This condition can occur in any vein, it occurs most often in the veins of the lower extremities (legs). Thrombophlebitis is more common in people with certain underlying conditions and in those who have been seated for a long period of time (e.g., in a car or airplane).

Blood usually circulates very quickly through the upper body, but this is not the case in the lower extremities. Contrast dye that is injected into the veins of the calves takes quite awhile to flow back up the leg, into the trunk, and into the heart. It takes even longer when the patient is upright. The calf and thigh are both very muscular and every time the muscles of the calves and thighs flex, they compress the veins and help propel blood back to the heart. The blood is then prevented from going right back down by a system of valves.

Proper function of the legs requires good muscle tone, good valves in the veins, and often, no family history of varicose veins. As a general rule, varicosities occur because of a breakdown in the venous system. Varicose veins are usually not a serious problem and rarely become inflamed.

However, varicosities in the deep veins cause a problem. In the calf, there are about 3 deep veins that come together near the knee to join one large deep vein located in the thigh. Generally, clots begin to form in the calf veins. When a person sits for a long period of time, the position of the knee (bent) narrows the vein coming from the lower leg, and the position of your thigh narrows the vein coming up from the thigh to the trunk. The net result is that the flow of blood in the venous system of the calf slows considerably. Blood flows very slowly clots easily, and clots propagate and inflame the vein, causing thrombophlebitis.

Although painful, thrombophlebitis is only part of the problem. More seriously, small blood clots can dislodge, pass through the thigh, into into the groin, through the abdomen, and into the heart. From the heart, assuming that the chamber walls are intact, the clots enter the pulmonary arteries and the small vessels that supply the lungs (called pulmonary emboli). Very small pulmonary emboli may go unrecognized for a brief time and large clots cause death very quickly.

Pulmonary emboli cause extensive damage to the lungs and must be avoided. Therefore, thrombophlebitis also must be avoided. Once blood clots develop in the deep veins, it is important that they are diagnosed and treated quickly, before emboli occur. Treatment usually includes hospitalization, bed rest, and vigorous anticoagulation (blood thinning) medication.

Clinical signs and symptoms that suggest thrombophlebitis include a swollen, red calf, and pain upon flexing of the ankle (Homan's sign). To diagnose thrombophlebitis, physicians often perform diagnostic tests to detect blood clots.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 May 2000

Last Modified: 06 Oct 2015