venous thrombosis

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Related to venous thrombosis: Venous thromboembolism, Cerebral venous thrombosis


formation, development, or presence of a thrombus; this can happen whenever the flow of blood in arteries or veins is impeded. Many factors can interfere with normal blood flow: heart failure or physical inactivity may retard circulation generally; a change in the shape or inner surface of a vessel wall may impede blood flow, as in atherosclerosis; a mass may grow inside the body and exert pressure on a vessel; the vessel wall may be injured and roughened by an accident, surgery, a burn, cold, inflammation, or infection; or the blood may thicken in reaction to the presence of a foreign serum or snake venom. adj., adj thrombot´ic.

Sometimes a thrombus detaches itself from the wall and is carried along by the bloodstream. Such a clot is called an embolus, and the condition is known as embolism. A thrombus may form in the heart chambers, such as after coronary thrombosis (see below) at the place where the wall of the heart is weakened, or in the dilated atria in a case of mitral stenosis. Because blood normally flows more slowly through the veins than through the arteries, thrombosis is more common in veins than in arteries.
Venous Thrombosis. This occurs most often in the legs or pelvis; it may be a complication of phlebitis, result from injury to a vein, or occur with prolonged bed rest. The symptoms—a feeling of heaviness, pain, warmth, or swelling in the affected part, and sometimes chills and fever—do not necessarily indicate its severity. Immediate medical attention is necessary in any case. Under no circumstances should the affected limb be massaged.

In thrombosis of superficial veins, bed rest with legs elevated and application of heat to the affected area may be all that is necessary. In thrombosis of deep veins, the affected part must be immobilized to prevent the clot from spreading or turning into an embolus, and anticoagulant drugs may be given. With proper treatment, recovery occurs within a short time unless an embolism develops. Practice management guidelines for venous thromboembolism in trauma patients note that a vena cava filter should be considered in patients at high risk who are not candidates for anticoagulants.
Prevention of Venous Thrombosis. Immobility is a prime factor in the development of thrombosis; hence, all patients should be mobilized as soon as possible after surgery or an illness that requires bed rest or produces paralysis. Those who cannot get out of bed should follow an exercise routine involving either active or passive motion of the extremities.  dehydration also plays a role in the development of thrombosis, and the patient should be kept well hydrated. The use of sequential compression devices, such as graded elastic stockings or automated devices providing intermittent compression to the legs, are widely used and accepted, but there are few clinical studies related to their use. They probably play a role in the prevention of stasis and should be combined with other methods to prevent thromboembolism. Clinical guidelines also support the use of low molecular weight heparin for patients at high risk when the bleeding risk is not considered a problem.
Arterial Thrombosis. The main types of arterial thrombosis are related to arteriosclerosis, although thrombosis can also result from infection or from injury to an artery. Arteriosclerosis may be hereditary or may be brought on by diabetes mellitus. Coronary thrombosis, arterial thrombosis in a coronary artery, is a complication of coronary atherosclerosis. A thrombus in one of these arteries will block part of the blood supply to the heart muscle and cause severe myocardial infarction, which is a medical emergency. Cerebral thrombosis is arterial thrombosis in one of the cerebral arteries; the thrombus obstructs the supply of blood to the brain and results in stroke syndrome. Causes include hardening of the cerebral arteries, hypertension, complications of syphilis or other infections, dehydration, diabetes mellitus, or a violent injury.

In advanced cases of arteriosclerosis, a thrombus may fill up whatever channel remains through a vessel, completely blocking off circulation and causing gangrene. This occurs most frequently in arteries of the legs and is called peripheral thrombosis. The onset, often sudden, is characterized by either a tingling feeling or numbness and coldness in the limb. Pain is not always present. Immediate treatment with anticoagulants is necessary to discourage clotting. If this is not effective, surgery may be required. This condition is most common in the elderly and in diabetics. There are now methods of treatment that may save the limb, such as surgical removal of a thrombus or embolus, or surgery of blood vessels to remove old, narrowed, or deteriorated vessels and replace them with grafts.
cerebral thrombosis arterial thrombosis of a cerebral vessel, which may cause stroke syndrome; see also thrombosis.
coronary thrombosis arterial thrombosis in a coronary artery, which may cause myocardial infarction. See also thrombosis.
deep venous thrombosis (DVT) venous thrombosis of one or more of the deep veins of the lower limb, characterized by swelling, warmth, and erythema; it is frequently a precursor of a pulmonary embolism. See also thrombosis.
venous thrombosis phlebothrombosis.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(throm-bo'sis) [ thrombo- + -osis]
The formation or presence of a blood clot within the vascular system. This is a life-saving process when it occurs during hemorrhage. It is a life-threatening event when it occurs at any other time because the clot can occlude a vessel and stop the blood supply to an organ or a part. The thrombus, if detached, can travel through the bloodstream and occlude a vessel distant from the original site; e.g., a clot in the leg may break off and cause a pulmonary embolus.


Trauma (particularly after an operation and parturition), cardiac and vascular disorders, obesity, hereditary coagulation disorders, age over 65, an excess of erythrocytes and of platelets, an overproduction of fibrinogen, and sepsis are predisposing causes.


Lungs: Obstruction of the smaller vessels in the lungs causes an infarct that may be accompanied by sudden pain in the side of the chest, similar to pleurisy; also present are the spitting of blood, a pleural friction rub, and signs of consolidation. Kidneys: Blood appears in the urine. Skin: Small hemorrhagic spots may appear in the skin. Spleen: Pain is felt in the left upper abdomen. Extremities: If a large artery in one of the extremities, such as the arm, is suddenly obstructed, the part becomes cold, pale, bluish, and the pulse disappears below the obstructed site. Gangrene of the digits or of the whole limb may ensue. The same symptoms may be present with an embolism.

If the limb is swollen, one should watch for pressure sores. Burning with a hot water bottle or electric pad should be guarded against. Prolonged bedrest may be necessary, depending on the patient's condition.


Pathological clots are treated with thrombolytic agents (such as streptokinase), antiplatelet drugs (such as heparins or aspirin), anticoagulants (such as warfarin), or platelet glycoprotein receptor antagonists (such as abciximab). When a thrombus or embolus is large and life threatening, surgical removal may be attempted.

cardiac thrombosis

Coronary occlusion.

catheter-associated thrombosis

A thrombosis that forms around a central venous catheter or the electrical leads of a defibrillator or pacemaker.

cerebral sinovenous thrombosis

A thrombosis in one of the main veins that carry blood from the brain, such as the superior sagittal sinus, the lateral sinus, or the straight sinus.

coagulation thrombosis

Thrombosis due to coagulation of fibrin in a blood vessel.

coronary thrombosis

Coronary occlusion.

deep vein thrombosis

, deep venous thrombosis Abbreviation: DVT
A thrombosis in one or more of the deep veins of the legs (the most common site) or the veins of arms, pelvis, neck, axilla, or chest. The clot may damage the vein or may embolize to other organs, e.g., the heart or lungs. Such emboli are occasionally fatal. See: pulmonary embolism


DVT results from one or more of the following conditions: blood stasis, e.g., bedrest; endothelial injury, e.g., after surgery or trauma; hypercoagulability, e.g., factor V Leiden or deficiencies of antithrombin III, protein C, or protein S; congestive heart failure; estrogen use; malignancy; nephrotic syndrome; obesity; pregnancy; thrombocytosis; or many other conditions. DVT is a common occurrence among hospitalized patients, many of whom cannot walk or have one or more of the other risk factors just mentioned.


The patient may report a dull ache or heaviness in the limb, and swelling or redness may be present, but just as often patients have vague symptoms, making clinical diagnosis unreliable.


Compression ultrasonography is commonly used to diagnose DVT (failure of a vein to compress is evidence of a clot within its walls). Other diagnostic techniques include impedance plethysmography and venography.


Unfractionated heparin or low molecular weight heparin (LMWH) is given initially, followed by several months of therapy with an oral anticoagulant such as warfarin. The duration of therapy depends on whether the patient has had previous thrombosis and whether, at the end of a specified period of treatment, the patient has an elevated D-dimer level: patients with increased D-dimers after several months of treatment with anticoagulants are more likely than other patients to have recurrent clots if their anticoagulant regimen is discontinued..


Pulmonary emboli are common and may compromise oxygenation or result in frank cardiac arrest. Postphlebitic syndrome, a chronic swelling and aching of the affected limb, also occurs often.


In hospitalized patients and other immobilized persons, early ambulation, pneumatic compression stockings, or low doses of unfractionated heparin, LMWH, or warfarin may be given to reduce the risk of DVT.

effort thrombosis

Paget-Schreutter syndrome

embolic thrombosis


hepatic vein thrombosis

An often fatal thrombotic occlusion of the hepatic veins, marked clinically by hepatomegaly, weight gain, ascites, and abdominal pain. Synonym: Budd-Chiari syndrome

infective thrombosis

Thrombosis in which there is bacterial infection.

marasmic thrombosis

Thrombosis due to wasting diseases.

mural thrombosis

Mural thrombus.

placental thrombosis

Thrombi in the placenta and veins of the uterus.

plate thrombosis

Thrombus formed from an accumulation of platelets.

postpartum ovarian vein thrombosis

A relatively rare, but potentially severe complication of some deliveries, e.g., caesarean births, and of pelvic inflammatory disease, in which one (typically the right) or both ovarian veins becomes clotted and infected. Common findings are abdominal pain, fever, nausea, and, often, a localized mass on physical assessment of the patient. The disorder is usually treated with anticoagulants and antibiotics although surgical excision of the clot is sometimes needed.

puerperal thrombosis

Coagulation in veins following labor.

septic thrombosis

An infected blood clot usually found in the heart or the venous sinuses of the brain.

sinus thrombosis

Formation of a blood clot in a venous sinus.

stent thrombosis

A blood clot that forms inside a device inserted into a blood vessel to keep that vessel open.

Patient Care

Stents are deployed in completely obstructed or partially blocked arteries to keep blood flowing through them to the organs they supply. When this blood flow stops due to clotting within the stent, the organ may become ischemic and die. To reduce the risk of clotting within a stent, patients use antiplatelet drugs, like aspirin, dipyridamole, or clopidogrel, and medications to lower serum lipid levels. Tobacco cessation, and healthy lifestyle changes (eating lighter, exercising regularly) may also be helpful.

traumatic thrombosis

Thrombosis due to a wound or injury of a part.

venous thrombosis

Thrombosis of a vein.
Medical Dictionary, © 2009 Farlex and Partners

Patient discussion about venous thrombosis

Q. Are long flights dangerous? I'm flying next week to my vacation, and the flight is going to be rather long (almost 16 hours non-stop). Several years ago, my 75 years-old aunt had blood clot in her lung after a flight of similar length. I also heard that during flight the blood in the legs clots and that it can cause after that problems with the lungs and breathing. Does this mean it's dangerous for me to fly? Should I change my ticket to shorter connection flights?

A. Do other relatives of yours have blood clotting problems too, like your aunt? You should tell a doctor about the problem your aunt had and ask if it's genetic.

Q. How can I prevent blood clots? I am 45 years old and am supposed to go on a business trip overseas. The flight itself is 12 hours long and then I have to continue traveling by bus. Could this cause me to have blood clots? If so, how can I prevent it?

A. Always walk as much as you can on the plane. Also, rotate your ankels in circles. Sometimes try to use your ankels and make the alphabet with them. Have fun..

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References in periodicals archive ?
Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls.
Analysis of deep venous thrombosis after gynecological surgery: A clinical study of 498 cases.
Keywords: Deep venous thrombosis, Laparoscopic cholecystectomy, Thromboprophylaxis.
Epidemiology, endovascular treatment, and prognosis of cerebral venous thrombosis: US center study of 152 patients.
However, the estimated rate of this mutation for myocardial infarction, stroke or venous thrombosis was found as 1.05 in "The Physicians Health Study" evaluating 14916 cases prospectively (20).
Deep venous thrombosis associated with pulmonary tuberculosis and transient protein S deficiency.
Renal venous thrombosis in an infant with predisposing thrombotic factors: color Doppler ultrasound and MR evaluation.
Unlike arterial thromboembolism, venous thrombosis is unrelated to atherosclerosis.
Ivanicova et al., "Noncontrast CT in deep cerebral venous thrombosis and sinus thrombosis: Comparison of its diagnostic value for both entities," American Journal of Neuroradiology, vol.
Gandhi, "Venous thrombosis: causes and imaging appearance," Hematology/Oncology Clinics of North America, vol.
Incidence and risk factors of early venous thrombosis associated with permanent pacemaker leads.
Point of Care Ultrasound (POCUS) for the diagnosis of suspected lower extremity deep venous thrombosis (DVT) is a well-established practice in the medical literature.