There are three types of veins in the human body: superficial veins, perforating veins and deep veins. Deep veins are connected to the vena cava, which is the largest vein in the body and is directly connected to the lungs and heart. Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein. DVT is most likely to occur in the calf, pelvis or thigh, though it can occur in other areas such as the chest or arm.
While half of patients with DVT will not experience symptoms, the other half is likely to experience:
- Sudden swelling or pain
- Skin warmth
- Leg pain that worsens during walking or standing
- Red or blue skin discoloration
DVT is a particularly dangerous condition because it can result in a pulmonary embolism. This occurs when a blood clot in one of the deep vein breaks away and travels to the lungs. Once there, the clot can block blood flow, straining the lungs and heart. A pulmonary embolism is considered an emergency and can quickly be fatal if the clot is large enough.
The most common symptom of a pulmonary embolism is shortness of breath. Other symptoms may include:
- Chest pain that might reach into the shoulder, arm, jaw and neck
- Rapid breathing or heartbeat
- Restlessness and anxiety
- Coughing up blood
- Lightheadedness and fainting
DVT can result from a problem with the body's clotting system. In this case, a small clot causes inflammation that then allows larger clots to form. Additionally, poor blood flow in the leg veins increases the risk for DVT, especially during periods of prolonged motionlessness. Because of this, DVT has been called Economy Class Syndrome, since clots may form during long airplane trips where there is limited leg room. The truth, however, is that long flights rarely cause DVT. Most often, the condition is found in hospitalized, bedbound patients.
Other factors increasing the risk for DVT include:
- History of stroke, heart attack or congestive heart failure
- Inflammatory bowel syndrome