Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel. If thrombosis occurs in a vein, this is known as venous thrombosis. A venous thrombosis can detach itself and get into the lungs via the blood stream. If it blocks a blood vessel there, this causes a pulmonary embolism.

Three factors are essentially responsible for the development of thrombosis: A change in or damage to the vascular wall, a decrease in the flow velocity of the blood and an increased tendency for the blood to clot. Situations which facilitate one or more of these factors are risks for a venous thrombosis. They include surgery, injuries or cancers. Lengthy period of sitting or lying without moving the calf muscles is a particular risk for the development of leg vein thrombosis. This is because regular movement of the leg muscles works like a pump on the veins and helps to keep the bloodstream moving properly in the veins. If this muscle pump stops, the blood stream slows and blood clots can form in the deep leg veins.

Deep vein thrombosis is therefore so frightening because it can cause thrombosis and pulmonary embolism. Larger pulmonary embolisms located centrally in the lungs cause an acute life-threatening condition. Smaller peripheral pulmonary embolisms can cause pulmonary infarction and pneumonia.

A feeling of heaviness in the legs, swollen lower legs, overwarm lower legs, pain in the calves or in the popliteal fossa are symptoms which indicate possible venous thrombosis. However, all these symptoms are rather unspecific. Therefore, venous thrombosis is more often than not only picked up if the patient suffers a pulmonary embolism. If the mentioned symptoms occur directly after surgery, air travel or after long-term bed rest, immediate medical advice must be sought.

Deep vein leg thrombosis should not be confused with varicose veins. Varicose veins are superficial dilated veins. If there is damage to the venous valves, the blood flows back into the superficial veins time and again. In comparison to deep vein thrombosis, deep vein thrombosis has much lower risk profile than pulmonary embolism.

The symptoms of pulmonary embolism depend on the severity of the embolism. A pulmonary embolism can manifest itself through chronic chest pain, loss of consciousness, breath-dependant chest pain, shortness of breath, feverish cough and bloody phlegm.

If there is suspicion of a deep leg thrombosis, special examinations of the leg and a blood examination carried out. The diagnosis is secured with special ultrasound examination, i.e., a Doppler sonography of the veins. Blood tests, x-ray and MRI of the lungs are carried out to diagnose pulmonary embolism.

The treatment of vein thrombosis focuses primarily on preventing pulmonary embolism. Blood-thinning medication is used for this purpose. In the acute stage in the form of injections; then, in tablet form. Depending on the situation, blood-thinning medication must continue to be taken afterwards. The treatment for pulmonary embolism depends on the severity of the embolism itself. If the embolism is larger in size, it must be immediately removed or dissolved. As in the case of venous thrombosis, blood thinners are always used. If there is a concomitant lung infection, it is treated with antibiotics.

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