Thrombosis: Symptoms, Treatment

Brief overview

  • Most common localizations: Blood vessels of the legs (especially lower legs), pelvis or arms, superior or inferior vena cava. A special form is anal thrombosis (anal vein thrombosis).
  • Typical symptoms: swelling, redness, hyperthermia, pain and tightness, fever, accelerated pulse.
  • Treatment: compression bandage or compression stockings as well as elevation in the case of thrombosis in the extremities, anticoagulant medication, surgery if necessary (thrombectomy).
  • Causes: flow obstructions in the vessels (e.g. due to deposits on the vessel walls, constriction due to a tumor), slow-flowing blood (e.g. due to varicose veins, bed confinement, lack of fluids), increased blood coagulation (e.g. due to coagulation disorders, cancer or smoking)
  • Examinations: physical examination, blood test, imaging (e.g., ultrasound, phlebography (“vein x-ray”), further examinations as necessary depending on the individual case.
  • Prognosis: Possible complications are pulmonary embolism (pulmonary artery occlusion) and vascular and tissue damage (post-thrombotic syndrome).
  • Prevention: Avoid risk factors (e.g. lack of exercise, lack of fluids, overweight), wear compression stockings (e.g. on long flights), thrombosis injection if necessary.

Thrombosis symptoms

Symptoms of thrombosis in the leg

Thromboses form particularly frequently in the large veins of the lower leg. This is because blood flows back to the heart particularly slowly there, against the force of gravity. The most common signs of thrombosis are then:

  • Swelling of the calf, often also of the ankle region and the foot
  • Feeling of heaviness and tension in the lower leg
  • Water retention (edema)
  • pain in the lower leg, sometimes also in the foot, thigh or groin, which can resemble a sore muscle
  • tense (shiny) and bluish discolored skin
  • overheating of the lower leg
  • more visible skin veins (so-called warning veins)
  • slight fever
  • accelerated pulse

Even if some of the above symptoms are absent, thrombosis in the leg is still not excluded. In the same way, the mentioned thrombosis signs are not a proof that a leg vein thrombosis is really present.

Symptoms of thrombosis in the arm

The veins in the arm can also become blocked by blood clots. However, this happens much less frequently than in the leg. Typical thrombosis symptoms in the arm are:

  • Swelling and overheating of the affected arm
  • swelling of the hand
  • bluish protruding skin veins
  • partial reddish-purple discoloration of the arm
  • pain when pressure is applied to the arm and when the arm is moved

Symptoms of anal thrombosis (anal vein thrombosis)

Anal thrombosis is noticeable by a painful swelling in the anal area. It is often difficult to distinguish from hemorrhoids, but has a different cause:

In anal thrombosis, a small vein of the lower anal canal is blocked by a blood clot. In contrast, “hemorrhoids” colloquially refers to enlargement of the arteriovenous vascular cushion at the exit of the rectum (the technical term is hemorrhoidal disease).

Anal vein thromboses are very painful, especially because they are located directly in the area of the opening. However, they can usually be treated well. Learn more about symptoms, causes and treatment of anal thrombosis here!

Symptoms of cerebral venous thrombosis (sinus vein thrombosis)

In sinus vein thrombosis (SVT), blood flow in the veins in the brain is disrupted by a blood clot. Blood congestion often occurs. Especially in connection with the vaccination against the coronavirus Sars-Cov-2, cerebral venous thrombosis made headlines. After immunization, cerebral sinus and vein thrombosis occurred, albeit very rarely, in some vaccinated individuals.

Symptoms of cerebral venous thrombosis include the following:

  • Headache
  • nausea and vomiting
  • stiff neck
  • pressure pain in the face
  • epileptic seizures
  • paralysis symptoms
  • Sensory disturbances

In principle, thromboses can occur in all blood vessels of the body. Unlike thromboses in the extremities, however, the symptoms are often ambiguous. For example, severe pain or organ dysfunction may occur. Further medical examinations are always required to clarify such non-specific thrombosis symptoms.

Thrombosis treatment

In principle, three methods are available for the treatment of thrombosis:

  • Compression therapy
  • Medication
  • Surgery

Which method is used depends, among other things, on the location where the clot formed. Often, the different treatment approaches must also be combined.

The most important goal of thrombosis treatment is to prevent the clot from detaching from the vein wall and traveling with the bloodstream to vital organs. This is because there is then a risk of a so-called embolism (for example, a pulmonary embolism). The clot blocks an artery with potentially life-threatening consequences.

It is also important to avoid long-term, irreparable damage to the affected blood vessels, extremities or organs (post-thrombotic syndrome).

Elevation and compression

The compression bandage must extend well beyond the site of the thrombosis – i.e., below the knee in the case of thrombosis of the lower leg. It must be tight enough to compress the veins so that the blood flows better in them. However, it must not constrict the limb at any point.

A good way to achieve a sufficiently strong and uniform degree of compression is to use thrombosis stockings of compression class II.

Compression treatment should be continued long-term if veins have been damaged by thrombosis.

Thrombosis treatment with medication

Thrombosis treatment with medication is intended to prevent the blood clot from growing further and possibly being washed into the pulmonary arteries. In the best case, the medication can cause the body’s own substances (enzymes) to shrink the thrombus again or even dissolve it completely. Anticoagulant drugs can also prevent a new thrombosis from forming.

Acute treatment of thrombosis

Doctors start the treatment of thrombosis – regardless of its location – with so-called initial anticoagulation. This should begin immediately if thrombosis has been identified with certainty or high probability as the cause of the symptoms.

The anticoagulant fondaparinux is also suitable for initial anticoagulation – especially if patients have reacted to heparin administration with a life-threatening drop in the number of platelets. Fondaparinux is injected under the skin.

However, initial anticoagulation can also be carried out with drugs that are ingested, namely the so-called DOAKs (direct oral anticoagulants) rivaroxaban and apixaban.

Long-term treatment after thrombosis

Acute thrombosis treatment – usually after about five to ten days – is followed by maintenance therapy: patients receive an anticoagulant drug for at least three to six months to prevent a new clot from forming.

Today, physicians usually prescribe DOAKs such as apixaban, rivaroxaban or dabigatran. Before the introduction of DOAKs, however, vitamin K antagonists (such as phenprocoumon and warfarin) were the preferred choice for maintenance therapy. These are antagonists of vitamin K, which is important for blood clotting. Their correct dosage must be checked regularly by blood coagulation tests! With DOAKs, on the other hand, such checks are usually superfluous.

Some patients need to continue taking anticoagulants beyond the six months to prevent new blood clots (secondary prophylaxis). This may be necessary, for example, if someone has a temporarily increased risk of recurrence due to an accident, surgery or pregnancy.

In the case of tumor diseases, the risk of thrombosis may also be permanently increased. Even then, secondary prophylaxis with medication may be advisable in the longer term.

In any case, physicians carefully check whether prolonged use of anticoagulants is actually necessary and – if so – for how long, with which active ingredients and in which dosage. Although secondary prophylaxis prevents new blood clots, it also has the disadvantage of increasing the risk of bleeding. The benefits and risks of secondary prophylaxis must therefore be carefully weighed up.

Surgical treatment of thrombosis

In some cases of acute leg vein thrombosis, surgical intervention is the best treatment option. In this case, the doctor tries to grasp the blood clot (thrombus) with the help of a catheter and pull it out of the vein. This is also called “recanalization” (recanalization therapy) because the procedure reopens a blocked blood vessel.

Doctors also check whether there is an obstruction to flow in the vein that can be removed.

Recanalization therapy should be performed as early as possible to reduce the risk of postthrombotic syndrome. Possible complications of this type of thrombosis therapy include bleeding, but also accidental detachment of clot fragments. These could then travel further along the venous pathway toward the heart and then into the pulmonary circulation.

In individual cases, doctors insert a kind of “sieve” into the vena cava (vena cava filter) of patients with leg vein thrombosis, either permanently or temporarily. This is intended to prevent detached blood clots from being washed into the lungs. This intervention may be considered, for example, in patients who repeatedly suffer a pulmonary embolism despite anticoagulant medication.

Thrombosis: Causes and risk factors

Thromboses are blood clots that form in blood vessels – almost always in veins. They can basically have three different causes, which can exist alone or in combination:

  • Obstructions to flow in the blood vessel: damage/disease or deposits on the vessel wall or constriction of the blood vessels due to mechanical pressure from outside (e.g. in scarring, tumors).
  • increased tendency of the blood to clot: in the case of diseases of the blood coagulation system, severe systemic diseases (cancer, autoimmune diseases), due to smoking or when taking certain medications (e.g. the “pill”) as a side effect.

Travel thrombosis and thrombosis after surgery

Blood return to the heart must function against gravity in the deep veins of the legs. This is assisted by two mechanisms in healthy, physically active people:

  • Venous valves: They act like valves and allow blood to flow in only one direction, toward the heart.
  • Muscle pump (muscle-vein pump): Through the work of the (calf) muscles, the veins in the leg are repeatedly compressed briefly. In cooperation with the venous valves, the blood is thus pressed in the direction of the heart.

If one or even both of these mechanisms are not working, the blood flow can slow down considerably – the risk of thrombosis increases. This is the case, for example, when sitting for long periods in a car, plane or train. Thrombosis in such cases is therefore often called “travel thrombosis.”

Sitting for hours at a computer can also increase the risk of thrombosis.

Thrombosis in varicose veins

Varicose veins (varices) are severely dilated blood vessels. They occur particularly frequently in the area of the legs, especially the lower legs.

Blood flows more slowly in varicose veins, and in addition, the natural valves in the veins (venous valves) no longer function properly here. This increases the risk of thrombosis.

Read more about the causes and treatment of varicose veins in our article Varicose veins.

The most important risk factors

So there are a number of factors that promote venous thromboembolism – that is, the formation of blood clots and their movement with the bloodstream, so that they clog a vessel elsewhere. The biggest risk factors are:

  • Leg fracture
  • Hospitalization for heart failure or atrial fibrillation or atrial flutter (in the previous three months)
  • use of an artificial hip or knee joint
  • severe trauma (e.g. as a result of a car accident)
  • heart attack (in the previous three months)
  • spinal cord injury
  • previous venous thromboembolism (e.g. pulmonary embolism)

Moderate risk factors include, for example, use of hormonal contraceptives, cancer, chemotherapy, superficial venous thrombosis, infections (especially pneumonia, urinary tract infections, and HIV infection), stroke with paralysis, and inflammatory bowel disease.

Thrombosis: Diagnosis and examination

In the case of venous thrombosis in a leg, the leg is overheated and swollen. Certain pressure points and movements trigger pain, which the doctor (usually a specialist in internal medicine) can determine with a physical examination. Typical symptoms include:

  • Calf pain when the top of the foot is lifted (Homans’ sign)
  • Pain when pressing the calf (Meyer’s sign)
  • Pressure pain on the inside of the foot (Payr’s sign)

In general, superficial thrombosis is characterized by more severe symptoms and is therefore often easier to diagnose than vascular occlusion in deeper veins (phlebothrombosis). The latter, however, more often has serious consequences.

Special scoring systems (scores such as the Wells score) help physicians assess whether a patient actually has deep vein thrombosis:

Points are awarded if certain parameters indicative of such thrombosis are present – for example, active tumor disease, swelling of the entire leg, or major surgery in the previous three months. The more points that add up, the higher the probability of deep vein thrombosis.

Blood test

If the measured value is within the normal range, acute thrombosis is unlikely. However, D-dimer measurement alone is not sufficient to rule out thrombosis. Physicians must also consider the other findings.

Imaging diagnostics

In addition, an ultrasound examination can provide a visual representation of vein occlusion.

With a phlebography (also: phlebography), the blood vessels can be visualized on an X-ray image. The procedure is therefore well suited for diagnosing deep vein thrombosis.

For this purpose, a contrast medium is injected into a superficial vein on the back of the foot. To ensure that the contrast medium finds its way into the deep veins of the leg, the veins near the surface of the skin are first tied off with a moderately tight bandage. Where there is thrombosis, the flow of the contrast medium is interrupted or appears “constricted,” which can be seen on the X-ray images.

In selected cases, vascular imaging is performed with the aid of magnetic resonance imaging (MRI) after administration of a contrast agent. This procedure uses magnetic fields and radio waves for imaging and not X-rays like computer tomography.

In rare forms of vascular occlusion, additional tests may be needed, such as funduscopy for thrombosis in the eye.

Thrombosis & pregnancy

Some women develop thrombosis during pregnancy or after a stillbirth/miscarriage. In that case, additional testing is advisable to find the cause. This can help prevent another thrombosis in a later pregnancy, if necessary.

Other special cases

In the case of thromboses that have no clearly identifiable cause or occur in atypical vessels, physicians will also make additional attempts to find the cause of the clot formation. For example, some people suffer from hereditary diseases that can disrupt blood clotting. Genetic testing may be indicated for detection.

Thrombosis: Course of the disease and prognosis

Thrombosis is a very serious disease and can lead to dangerous complications. These arise,

  • when a vein is blocked by a thrombus and permanently damaged (consequence: postthrombotic syndrome).

Pulmonary embolism

Pulmonary embolism is a particularly common and life-threatening complication of thrombosis. The thrombus (or parts of it) is carried by the bloodstream through the venous system to the right ventricle and from there into the pulmonary arteries.

If it obstructs a large artery there, a large part of the lung is no longer supplied with blood. It can then no longer participate in gas exchange, which can cause a life-threatening oxygen deficiency.

In addition, the right ventricle of the heart is overloaded trying to pump blood into the clogged pulmonary vessel against the high flow resistance – right heart failure (a form of heart failure) can result. Therefore, an embolism is always a medical emergency!

Read more about the symptoms and treatment of this serious complication in the article Pulmonary Embolism.

Postthrombotic syndrome

Some patients with deep pelvic or leg vein thrombosis develop a so-called postthrombotic syndrome. In this case, varicose veins form due to the clot-induced blood outflow obstruction, which persists even after the affected vessels have been reopened. This outflow obstruction can cause further tissue damage and/or repeat blood clots.

Prevent thrombosis

In addition, adequate hydration (drinking, liquid foods) is important to keep the blood thin to prevent clot formation.

Thrombosis injections

After an injury or surgery or other immobilization due to illness, medication can be used to prevent clot formation: daily thrombosis injections with heparin can prevent the formation of a blood clot in most cases.

Anti-thrombosis stockings

So-called anti-thrombosis stockings are special elastic stockings made of a skin-friendly, thin fabric that either reach down to the knee, or even extend beyond the knee to include the thigh. The slight pressure they exert on the veins causes the blood to flow back to the heart a little faster and more evenly.

Wearing anti-thrombosis stockings is especially recommended if you have thrombosis risk factors such as a tendency to varicose veins, before and after surgery, and on long trips. They can often help prevent thrombosis.