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Blood Clot in the Legs

Leg Blood Clot Overview

Deep venous thrombosis (DVT) refers to a blood clot embedded in one of the major deep veins of the lower legs, thighs, or pelvis. A clot blocks blood circulation through these veins, which carry blood from the lower body back to the heart. The blockage can cause pain, swelling, or warmth in the affected leg.

Blood clots in the veins can cause inflammation (irritation) called thrombophlebitis. The most worrisome complications of DVT occur when a clot breaks loose (or embolizes) and travels through the bloodstream and causes blockage of blood vessels (pulmonary arteries) in the lung. This can lead to severe difficulty in breathing and even death, depending on the degree of blockage.

In the United States, about 2 million people per year develop DVT. Most of them are aged 40 years or older. Statistics reveal that at least 200,000 patients die each year from blood clots in their lung.

Leg Blood Clot Causes

Three factors may lead to formation of a clot inside a blood vessel.

Damage to the inside of a blood vessel
Changes in normal blood flow, including unusual turbulence or partial or complete blockage of blood flow
Hypercoagulability - A rare state in which the blood is more likely than usual to clot

Any component that contributes to 1 or more of these 3 criteria can cause DVT. The more common risk factors are as follows:

Prolonged sitting, such as during a long plane or car ride
Prolonged bed rest or immobility, such as after an injury or during an illness ( stroke)
Recent surgery, particularly orthopedic, gynecologic, or heart surgery
Recent trauma to the lower body, such as fractures of the bones of the hip, thigh, or lower leg
Obesity
Heart attack or heart failure
Recent childbirth
Being at very high altitude, greater than 14,000 feet
Use of estrogen replacement (hormone replacement therapy, or HRT) or birth control pills
Malignant tumors ( cancer)
Rare inherited genetic changes in certain blood clotting factors
Disseminated intravascular coagulation (DIC), a medical condition in which blood clotting occurs inappropriately, usually caused by overwhelming infection or organ failure