Thrombosis is a serious condition in which blood clots form in the veins and block vital blood flow. Learn more about what thrombosis is, its causes and symptoms, and how it can be treated.

The early detection of thrombosis saves lives

Our heart pumps around 10,000 liters of blood through our body every day, beating about 100,000 times. As blood flows through our blood vessels, it supplies oxygen to tissues and organs.

A thrombosis is present as soon as a blood clot prevents the flow of blood in the veins. If a blood clot detaches from the vessel wall, a dangerous pulmonary embolism can result.

If you suspect thrombosis, do not hesitate to have your symptoms examined by our experienced as well as trained doctors at the Venenzentrum am See in Feldmeilen.

What is thrombosis?

Thrombosis is the partial or complete occlusion of a blood vessel. This causes the blood to clot and the platelets to form a clot – also called a thrombus or blood clot. This results in a backlog. A common symptom is swelling of the leg and acute pain.

Thrombosis can occur in any section of the venous system. However, it most commonly occurs in the deep veins of the legs. If a blood clot forms in the vein, doctors refer to it as venous thrombosis.

Thrombosis: causes

The development of thrombosis can have different causes. These are usually characterized by three factors, also known as the “Virchow triad:”

Slowed blood flow: Blood flows more slowly due to abnormally dilated veins(varicose veins) or insufficient muscle tone after surgery or in the absence of fluids.

Impaired blood flow: The blood vessel walls show damage or deposits, for example in varicose veins.

Increased tendency to clot: Blood clotting is increased and the blood clots more quickly. This may be due to a genetic change in blood clotting or to other systemic diseases such as cancer or autoimmune disorders.

Thrombosis cause

How can thrombosis occur?

It is believed that the occurrence of thrombosis is often related to events such as vascular damage, congestion due to prolonged sitting/lying, or a change in clotting factors.

Risk factors for the development of thrombosis:

  • surgical interventions
  • traumas
  • pregnancy
  • cancer
  • varicose veins
  • obesity
  • oral contraceptives (e.g. the “pill”)
  • hormone replacement therapy
  • certain drugs
  • advancing age
  • family predisposition
  • travel over longer distances
  • longer immobility

Why us as your vein doctor?


Over 25 years experience

At Venenzentrum am See, we have specialized in the treatment of vein disorders for about 25 years.


Minimally invasive procedures

As an alternative to surgical treatment of venous disorders, we prefer to use minimally invasive procedures.


Fast & uncomplicated appointment

You can quickly and easily make an appointment online or call us.


Outpatient & painless treatment of venous disorders

The use of minimally invasive procedures allows for outpatient and low-pain treatment.


Comprehensive diagnostics & patient education

We offer a holistic vein clarification with the most modern equipment available.


Practice in central location

Our practice is in a preferred location near the Herrliberg-Feldmeilen train station.

Thrombosis symptoms: first signs

Symptoms and signs vary depending on the size and location of the blood clot. Some patients do not show any symptoms (at first). For this reason, a diagnostic evaluation by a vein specialist should take place promptly at the first signs of thrombosis.

Thrombosis symptoms in the leg

The following thrombosis symptoms in the leg are signs of a possible clot formation:

  • A feeling of heaviness in the affected leg
  • muscle-like and pulling pain in the entire leg
  • pain in the lower leg, tenderness
  • more visible veins
  • calf pain with pressure
  • one-sided water retention (edema) in the calves, swelling of the leg
  • unilateral water retention on the ankle
  • bluish discolored and tense skin


Thrombosis in the arm

Thrombosis in the arm is far less common. Thrombosis in the arm is very painful in most cases. The veins stand out on the surface of the skin and the arm swells.

Deep vein thrombosis

In deep vein thrombosis, the blood clot forms in a deep vein – usually in the upper and lower leg.

Superficial venous thrombosis

In a superficial vein, a blood clot occurs together with phlebitis, usually in a varicose vein (varicose vein).

Thrombosis – treatment

Compression therapy

One treatment method for thrombosis is the use of compression stockings or bandages. For the blood to flow faster again, these exert pressure on the vein and relieve the pain. Compression stockings also reduce the risk of recurrence of thrombosis.


Depending on the localization and size, a different therapy with anticoagulant drugs is necessary.

Have vein problems treated

Prevent thrombosis

To prevent thrombosis, you can take several measures yourself:

  • Ensure sufficient and regular exercise.
  • When traveling long distances, make sure you are as mobile as possible: Walk a few steps on the plane and take enough breaks to move around during car rides. Wear compression stockings.
  • Drink enough water: Sufficient fluid intake is important to keep the blood thin and prevent thrombosis from forming.
  • Make sure you have a healthy weight.
  • Check with your doctor before surgery to see if preventive treatment for thrombosis is necessary.
  • Find out from your relatives about any blood abnormalities in the family
  • If women have had a thrombosis, they should talk to their gynecologist about alternative contraceptive methods to estrogens and also make them aware if they are planning a pregnancy.


Anti-thrombosis stockings: compression stockings for the prevention of thrombosis

Wear so-called anti-thrombosis stockings to prevent a blood clot. Especially on long-haul flights or long-distance car journeys, sitting for long periods has a detrimental effect on the leg veins. Anti-thrombosis stockings are thin and elastic and usually reach the knee. They exert a slight pressure on the vein and thus promote a faster as well as more even blood flow to the heart. To get the right anti-thrombosis stockings, check with a vein specialist. We will be happy to advise you at the Venenzentrum am See!

Thrombosis | Vein doctor Feldmeilen
Thrombosis self-test - How to recognize thrombosis

Watch for possible thrombosis symptoms: tightness in an area, pain similar to a sore muscle, and changes in the skin may be the first signs of a blood clot. The following factors may indicate an increased risk for thrombosis:

  • pain and hardening in the leg
  • blood clotting tendency
  • swelling on the leg
  • recent history of cancer or bedriddenness
  • heart disease or diabetes
  • overweight
  • already occurred deep vein thrombosis

A self-test is not a substitute for a doctor’s diagnosis. Be sure to see a vein specialist if you have any signs and/or concerns.

What is the difference between thrombosis and embolism?

If parts of the blood clot break off or travel with the blood flow, they can block a vessel elsewhere in the body. The thrombus is now no longer called a thrombus but an embolus. This can trigger an embolism. In a pulmonary embolism, one of the vessels through which blood travels from the heart to the lungs is blocked.

Make an appointment!

Our vein doctors at Venenzentrum am See specialize in modern minimally invasive methods for treating vein conditions. Benefit from our many years of experience and expertise and let our competent team advise and treat you.