Blood clotting, or thrombosis, is a protective mechanism that occurs naturally to prevent excessive bleeding when the body is injured. It can become a problem, however, if blood clots form in veins and obstruct proper blood flow.
Clotting can occur in superficial veins (close to the surface of the skin) or deep veins (those lying deeper in the body), under layers of muscle or in body cavities. When blood clots form in the veins that lie close to the skin surface in its fat layer, the resulting condition is called superficial thrombosis or phlebitis. It can cause some skin irritation and discomfort, but is rarely considered a serious medical problem.
When blood clots develop in the deeper veins, however, it is called deep vein thrombosis or DVT, and is a more serious condition that requires immediate medical attention. The obstruction caused to venous blood flow by these deeper clots or thrombi is a concern, but the real danger from DVT is that the clots can break loose from where they originally formed and travel through the veins to other locations in the body.
If the clots travel to the brain they can cause a stroke, and if they travel to the lungs they can cause a pulmonary embolism (PE). Both are life threatening conditions, and in fact the latter happens often enough that it is referred to by a combined acronym, DVT/PE. This condition has been estimated to affect close to a million people worldwide, and several hundred thousand people die from it every year.
Symptoms of DVT and DVT/PE
Symptoms of deep vein thrombosis can include swelling, tenderness, and warmth of the skin in the area over which the clot has formed. However, over half of patients with DVT are "asymptomatic" and display no overt indications of the condition. Symptoms of DVT/PE, however, are much more striking, and include:
- Sharp chest pain that gets worse when you cough, breathe deeply, bend over, or stoop, and that doesn't go away when you rest.
- Shortness of breath, especially if it gets worse after exercise.
- A cough that produces bloody sputum or pink, foamy mucus.
- Leg pain, swelling, or severe cramps, usually in the calf muscles.
- Fever or excessive sweating.
- Clammy or discoloured skin, often accompanied by feelings of anxiety.
- Sudden lightheadedness, dizziness, or fainting.
- Rapid or irregular heartbeat.
If you experience any of these symptoms, you should seek immediate medical care.
What are the risk factors for DVT, and do they include having varicose veins?
Risk factors that increase your likelihood of developing DVT are similar to those for other vein diseases, and include age (being over 60), heredity (whether family members have had it), obesity, smoking, pregnancy, and the use of oral contraceptives or hormone replacement therapy (HRT). Another risk factor for DVT is reduced mobility, caused by long periods of hospitalisation or sitting in one position for hours as the result of long-distance travel. DVT can also be triggered by injuries to blood vessels incurred as the result of trauma or during surgery.
The question of whether having varicose veins is a significant risk factor for DVT is more controversial, because a clear cause-and-effect relationship has not been firmly established. However, in a study reported in the German journal VASA, researchers found that 5.6% of patients with varicose veins developed DVT, compared to 0.9% of the control group without varicose veins. They also found that those with varicose veins who also had a history of previous venous thromboembolism or a recent hospital discharge were even more at risk.
Can DVT be treated?
In a word, yes. In most cases DVT, once diagnosed, can be effectively treated using anticoagulant medications such as heparin and warfarin. In some cases "clot busting" thrombolytic agents are used, and in rare cases surgery may be required.
To determine your own risk for DVT, ask your specialist at The Vein Institute. They can diagnose the presence of blood clots using Duplex ultrasound or venography (injecting a dye into the vein that then reveals blockages in X-rays). Your vein doctor can also recommend diet and lifestyle changes to reduce your DVT risk if your risk level is high for hereditary or other reasons.