Recognising and treating thrombosis

The term thrombosis is derived from the Latin term “thrombus”, which means plug or lump. It is a kind of vascular occlusion (closure), e.g. of a vein that supplies blood to the heart. In principle, a blood clot can form in all vessels of the body, but this mainly occurs in the deeper veins of the lower leg (deep vein thrombosis) or the thigh. It can also occur in the pelvic area or in the arms. A distinction is made between venous and arterial thrombosis.

A thrombus may dislodge in whole or in part and enter the lungs via the heart. This is dangerous because the clot can clog the blood vessels in the lungs, which are vital for breathing. This condition is known as pulmonary embolism. The larger the clot, the higher the risk.

Thrombosis often forms in the lower leg and exhibits typical signs, but these may manifest differently depending on the region and size of the blood clot.

Common symptoms of leg thrombosis include:

• Swelling in the affected area, e.g. calf or ankle
• Water retention
• Feeling of pressure or tension
• Muscle aches, potentially up to convulsions
• Blue colouring of the skin
• Protruding veins
• Warm areas of skin, reddening

There are various reasons why blood clots form in blood vessels. Often, they do so for a combination of reasons. On the one hand, the speed at which blood flows through the vein may be slower than normal. There are several possible reasons for this, such as dehydration, which causes the blood to thicken, varicose veins (enlarged veins) or insufficient muscle tone. On the other hand, a propensity for blood clotting may trigger thrombosis. This is due to certain diseases such as cancer, but also to certain medications (birth control pills) or smoking. Damage or constriction of the vascular wall should also be considered, e.g. due to deposits, tumours or scarring.

Other factors that may increase the risk of thrombosis include:

• Old age
• Genetic predisposition
• Heart failure
• Obesity
• Severe varicose veins
• Hormone intake
• Frequent air travel with long periods of sitting
• Several restricted mobility or immobility

Because the symptoms alone are not a certain indicator for an accurate diagnosis, doctors usually perform a blood test (D-dimer test). If a blood clot is present, this can be detected via substances that the body produces when a blood clot occurs.

If the result is positive, a duplex ultrasound is usually used to confirm the diagnosis. This provides further information about the state of the deep veins in the legs and the blood flow in them. If the suspicion of thrombosis is confirmed, an ultrasound examination is also performed.

In rare cases, an X-ray examination of the vessels is necessary, in which a contrast medium is injected into the vein via a catheter to make the thrombosis visible.