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Thrombosis is a process when a blood clot is formed in the blood vessel and obstructs it, causing congestion, ischemia and necrosis.


Thrombosis – an obstruction of the vessel by a blood clot formed within its lumen – it may affect both a vein or an artery. Normally, injury of the blood vessel causes the formation of a blood clot from fibrin fibers and platelets in order to prevent blood loss. However, blood clots may occur in the body under certain circumstances, even when the blood vessels remain intact. Venous thrombosis causes congestion of the affected body part / organ. Arterial thrombosis results in ischemia and, therefore, cell necrosis.


According to Virchow’s triad hypercoagulability (alterations in the constitution of blood), hemodynamic changes (stasis or turbulence) and endothelial injury/dysfunction (vessels’ lining damage) contribute to the thrombosis.


Risk Factors:

If a person experienced episodes of thrombosis in the past, he/she is more like to develop it in the future as well.

A variety of conditions decrease the speed of the blood flow and change the ability of the blood to coagulate and, therefore, result in thrombosis:

  • Vasoconstriction, slow or turbulent blood flow;
  • Age over 60 years;
  • Overweight or obesity;
  • Stroke;
  • Heart failure;
  • Sedentary lifestyle;
  • Dehydration;
  • Acute respiratory failure;
  • Dysrhythmias;
  • Shock;
  • Pregnancy and the period after the delivery;
  • Varicose veins;
  • Surgery, especially laparoscopy and long surgeries;
  • Trauma;
  • Estrogen-based oral contraceptive;
  • Hormone replacement therapy;
  • Infertility treatment;
  • Compression of a vein or artery by a tumor, hematoma;
  • Vein damage, valves insufficiency;
  • Central venous catheters and dialysis catheters;
  • Immobility (long travel times, flights and recovery after surgeries);
  • Varicose veins;
  • Spinal cord injury;
  • Cancers;
  • Septicemia;
  • Polycythemia;
  • Coagulopathies;
  • Antiphospholipid antibody syndrome;
  • Hyperhomocysteinemia;
  • Falls and hip fracture;
  • Selective estrogen-receptor modulators;
  • Erythropoiesis-stimulating agents;
  • Inflammatory bowel disease;
  • Nephrotic syndrome;
  • Myeloproliferative disorders;
  • Paroxysmal nocturnal hemoglobinnuria;
  • Thrombophilias;
  • Venous inflammation/phlebitis.


Symptoms of thrombosis vary depending on the type and localization of the obstructed vessel.

Venous thrombosis
  • Deep Vein Thrombosis – the formation of a blood clot within a deep vein, commonly the leg (femoral vein) is affected. The condition is characterized by the pain in the injured extremity, which appear bluish,  swollen with erythema and warmth. Along the vein a cord may be palpated. During the examination a doctor will detect positive Homan’s sign (pain with dorsiflexion of the foot) and pain on palpation. Superficial veins become prominent.

The detachment of the clot (embolization) may cause a life-threatening  pulmonary embolism.

  • Paget-Schroetter disease develops when the axillary or subclavian vein is occluded. It was called an effort-induced thrombosis in the past, because it’s more common for young males,  and the possible cause of the condition is the vigorous activity.
  • Budd-Chiary syndrome is a rare condition caused by the obstruction of the hepatic veins. The disorder is characterized by hepatomegaly, ascites and abdominal pain accompanied by the jaundice, splenomegaly and collateral vein prominence.
  • Portal vein thrombosis – a thrombosis of the hepatic portal vein that causes portal hypertension and decreased blood flow to the liver. The symptoms of the acute condition include such as the sudden pain in the right upper quadrant of the abdomen, nausea and fever. In chronic thrombosis mild hepatomegaly is often present and the right upper quadrant epigastric tenderness.
  • Renal vein thrombosis usually occurs due to hypercoagulation and invasion by renal cell cancer. The condition may be asymptomatic, flank pain and macroscopic hematuria may be present.
  • Cerebral venous sinus thrombosis – a rare form of the stroke caused by the obstruction of the dural venous sinuses by the blood clot. Symptoms may vary in connection with the injured brain area and usually include: headache, abnormal vision, weakness of the facial muscles and extremities on one side of the body, seizures, etc.
  • Internal jugular vein thrombosis causes the pain and swelling at the angle of the jaw and a palpable cord beneath the sternocleidomastoid muscle, but in some cases these symptoms may be absent. Other clinical manifestations include fever, neck swelling and cervical pain, cord signs, etc.

Arterial thrombosis occurs when a thrombus obstructs the lumen of the artery causing ischemia and therefore necrosis of the tissues and loss of function.

  • Ischemic stroke occurs when a blood vessel that provides the blood supply to the brain is occluded (due to a blood clot or embolus). The underlying condition is atherosclerosis. A person experiences confusion, troubles with speaking and understanding, headache, vomiting, numbness of the face, arm or leg, particularly on one side of the body, vision impairment, in one or both eyes, difficulties walking, including dizziness and lack of coordination as well as extremity weakness (paresis) or inability to move a body part or one side of the body (paralysis).
  • Myocardial infarction (heart attack)develops as the result of the obstruction of the coronary artery or its branches. The injured tissue necrotizes. The condition may be fatal unless the treatment is begun  immediately. The main symptom of the heart attack is chest pain (substernal pressure sensation, squeezing, aching, burning, or even sharp). This pain may irradiate to the other body parts, commonly the left upper limb or the jaw. A person is anxious, lightheaded, with or without syncope, he/she may be coughing or vomiting. Profuse sweating, shortness of breath, rapid or irregular heart rate are also characteristic.
  • Mesenteric ischemia  is caused by the decreased or ceased blood supply to the intestines. Acute ischemia develops when the blood supply is interrupted suddenly. Chronic ischemia occurs when the blood flow is constantly disturbed. The main symptom of the disease is the pain in the abdomen, usually it occurs after the meal.
  • Limb ischemia is an acute or chronic condition when the blood flow to the limb is decreased. Symptoms include “the six P’s”: pain, pallor, paresthesias, perishingly cold, pulselessness and paralysis of the affected extremity.


Diagnosis is based upon the history of the disease and clinical findings, blood test, ECG, ultrasound examination, angiography and/or CT/MRI depending on the type of thrombosis.

Check out the Thrombosis test


The risk of developing blood clots can be modified by lifestyle modifications, the discontinuation of oral contraceptives, increasing of exercises and weight loss. After the surgery the early standing up and walking is recommended to prevent venous stasis. The administration of antiplatelet drugs is recommended for persons with a history of thrombosis or high risks.


  • Anticoagulation therapy includes warfarin and other vitamin K antagonists (Coumatetralyl, Phenprocounmon, Phenindione, Fluindione);
  • Antiplatelet drugs (aspirin) prevent the new clot formation or the progression of the present thrombus;
  • Thrombolysis is the destruction of the blood clot by the administration of thrombolytic drugs (Alteplase, Streptokinase, Urokinase and others);
  • Endovascular surgery includes catheter-guided thrombolysis or clot retrival and helps restore the blood supply to the injured area;
  • Surgery – limb ischemia may result in gangrene that is an indication to surgical amputation of the extremity.  
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