AskDefine | Define thrombus

Dictionary Definition

thrombus n : a blood clot formed within a blood vessel and remaining attached to its place of origin [also: thrombi (pl)]

User Contributed Dictionary



  1. A blood clot formed from platelets and other elements; that forms in a blood vessel in a living organism, and causes thrombosis or obstruction of the vessel at its point of formation or travel to other areas of the body.


blood clot formed in blood vessels that leads to thrombosis
  • French: thrombus

See also



  1. thrombus

Extensive Definition

A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system (i.e. clotting factors). A thrombus is physiologic in cases of injury, but pathologic in case of thrombosis.
Specifically, a thrombus is a blood clot in an intact blood vessel. A thrombus in a large blood vessel will decrease blood flow through that vessel. In a small blood vessel, blood flow may be completely cut-off resulting in death of tissue supplied by that vessel. If a thrombus dislodges and becomes free-floating, it is an embolus.
Some of the conditions which elevate risk of blood clots developing include atrial fibrillation (a form of cardiac arrhythmia), heart valve replacement, a recent heart attack, extended periods of inactivity (see deep venous thrombosis), and genetic or disease-related deficiencies in the blood's clotting abilities.
Blood clot prevention reduces the risk of stroke, heart attack and pulmonary embolism. Heparin and warfarin are often used to inhibit the formation and growth of existing blood clots; they are able to decrease blood coagulation by inhibiting vitamin K epoxide reductase, an enzyme that recycles oxidated vitamin K to its reduced form after it has participated in the carboxylation of several blood coagulation proteins, mainly prothrombin and factor VII.
Virchow's Triad describes the conditions necessary for thrombus formation:
  1. Changes in vessel wall morphology (e.g. trauma, atheroma)
  2. Changes in blood flow through the vessel (e.g. valvulitis, aneurysm)
  3. Changes in blood composition (e.g. leukaemia, hypercoagulability disorders)
Disseminated intravascular coagulation (DIC) involves widespread microthrombi formation throughout the majority of the blood vessels. This is due to excessive consumption of coagulation factors and fibrinolysis using all of the body's available platelets and clotting factors. The end result is ischaemic necrosis of the affected tissue/organs and spontaneous bleeding due to the lack of clotting factors. Causes are septicaemia, acute leukaemia, shock, snake bites or severe trauma. Treatment involves the use of fresh, frozen plasma to restore the level of clotting factors in the blood.

See also

External links

thrombus in Arabic: جلطة
thrombus in German: Thrombus
thrombus in Spanish: Trombosis
thrombus in Esperanto: Trombo
thrombus in French: Thrombus
thrombus in Italian: Trombo
thrombus in Lithuanian: Trombas
thrombus in Hungarian: Thrombus
thrombus in Japanese: 血栓
thrombus in Polish: Zakrzep
thrombus in Portuguese: Trombo
thrombus in Quechua: Sirk'a unquy
thrombus in Russian: Тромб
thrombus in Swedish: Blodpropp
thrombus in Danish: Blodprop
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