Deep Vein Thrombosis

深層靜脈栓塞

Deep Vein Thrombosis

There are two systems of veins: Deep veins which are embedded inside muscles and superficial veins which are just underneath our skin. Deep vein thrombosis (DVT) means thrombosis (clotting) of blood in the deep veins of the legs

Why does deep vein thrombosis occur?

Stagnation of blood

During walking as muscle contract blood inside the deep vein is squeezed and pushed upward. When the legs are inactive, blood stagnate in the deep veins and clotted. The longer the period of stagnation, the more likely is thrombosis. E.g. long-haul flight

Thrombophilia (Blood clots too easily), Blood becomes unusually "thick" or "sticky"

Severe dehydration
Congenital medical condition: such as factor V Leiden mutation, protein C deficiency, etc
Acquired medical condition: such as cancer, after trauma, after surgery, etc

Who is at increased risk of deep vein thrombosis?

Having had a DVT or pulmonary embolism before
Having had a recent major operation
After long-haul flight or prolonged bed rest
Debilitated and immobile patient
Pregnancy and puerperal
Contraceptive pill or hormone replacement therapy (HRT)
Malignant disease (cancer)
Obesity (being overweight)
Severe heart disease
Some blood diseases with increased tendency to clot
Varicose veins

Consequences of deep vein thrombosis

Obstruction : Causing chronic lower limb pain, swelling, skin changes with increased pigmentation and chronic ulceration
- Blockage of the passage and pooling of blood
- Damage to the valves and allow abnormal backflow of blood
Pulmonary embolism (PE)
- Clot (thrombus) can dislodge from the vein, and carried along the blood flow through the heart to lodge in the lungs.
- PE may cause chest pain, coughing up of blood and breathlessness.
- PE can be fatal, if a large clot lodges in the main blood vessel to the lung and blocks the return of blood to the heart
Re-canulation of the thrombosed vein
Development of collateral circulation

What can be done to reduce the risk of DVT?

Move your legs
Stretching and moving the legs stops blood stagnating in the deep veins of the calf Avoid prolonged standing or sitting still. Change posture, flex your feet
Don't get dehydrated.
Drink plenty of water, Avoid alcohol, which tends to cause dehydration.
Wear compression stockings
Wear compression stockings, watch out for curl up of the stocking that produce constriction
Stop smoking
Smoking increases the tendency of the blood to clot.
Anticoagulation if indicated
If you have known history of DVT or recurrent DVT, consult your doctor for possible anticoagulation therapy

Treatment for DVT

Anti-coagulation to stop new clot from forming
Wear compression stocking to improve circulation inside the deep vein
Lyse or dissolve the clot for extensive thrombosis that threaten circulation