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thrombosis (thrŏmbōˈsĭs), obstruction of an artery or vein by a blood clot (thrombus). Arterial thrombosis is generally more serious because the supply of oxygen and nutrition to an area of the body is halted. Thrombosis of one of the arteries leading to the heart (heart attack; see infarction) or of the brain (stroke) can result in death and, in a vessel of the extremities, may be followed by gangrene. Acute arterial thrombosis often results from the deposition of atherosclerotic material in the wall of an artery, which gradually narrows the channel, precipitating clot formation (see arteriosclerosis). A thrombus that breaks off and circulates through the bloodstream is called an embolus.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the formation of blood clots during life in the lumen of a blood vessel or in the heart.

Thrombogenesis is promoted by injury to the vascular wall owing to atherosclerosis or inflammation, by the slowing of the blood flow, and by an increase in the coagulability and viscosity of the blood. Peripheral venous thrombosis is most common; thrombosis in the arterial system occurs less frequently. Arterial thrombosis interferes with the blood supply to areas of tissue and often leads to necrosis of such tissue. For example, coronary thrombosis results in myocardial infarction, and cerebral thrombosis, in a stroke, or cerebrovascular accident. The thrombus may subsequently either dissolve (undergo lysis), with partial or complete restoration of the blood vessel’s patency, or it may become thickened (organized). Multiple capillary thrombosis, a syndrome involving disseminated intravascular blood coagulation, is often combined with an increased tendency for tissues to bleed. The condition may develop during shock, hemorrhage, or severe infectious diseases, or it may be a manifestation of intolerance for drugs.

Biochemical and roentgenological methods of examination are used to diagnose thrombosis. Treatment includes the administration of anticoagulants, antispasmodics, and fibrinolytic and anti-inflammatory agents, as well as surgical removal of the thrombus.


Machabeli, M. S. Koagulopaticheskie sindromy. Moscow, 1970.
Kuznik, B. I., and V. P. Skipetrov. Formennye elementy krovi, sosudistaia stenka, gemostaz i tromboz. Moscow, 1974.
Raby, C. Lokalizovannaia i rasseiannaia vnutrisosudistaia koaguliatsiia. Moscow, 1974. (Translated from French.)
Quick, A. J. Hemorrhagic Diseases and Thrombosis, 2nd ed. Philadelphia, Pa., 1966.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Formation of a thrombus.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. the formation or presence of a thrombus
2. Informal short for coronary thrombosis
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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It would be more appropriate to reevaluate the patient after thrombosis recovers and the blood levels reach the adult level (after the age of 6 months-1 year) (4, 8, 32).
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This case demonstrates that prenatal diagnosis of umbilical artery thrombosis was a crucial step in avoiding possible serious adverse perinatal outcome [1-4].
Ultrasound diagnosis was a thrombosis of the renal vein with hypoperfusion of the renal artery.
Neurological involvement in BD occurs on average five years after the systemic findings are observed; it is observed 3-4 times higher in men than in women and the most common clinical presentation is sinus venous thrombosis at central nervous system (CNS) involvement; peripheral nerve or muscle involvement is very rare.
Contrast venography is considered the reference standard for the diagnosis of upper extremity thrombosis, but is infrequently performed due its invasive nature and the availability of noninvasive alternatives.
We present the case of a 29 year-old female patient, who developed during the 17th week of her second pregnancy an episode of superficial thrombophlebitis in the right external saphenous vein and the right popliteal vein, complicated in the 24th week with right ilio-femoral thrombosis, for which treatment with low molecular weight heparin (LMWH) was initiated.
Quantitative D-dimers and 3 risk stratification (Wells score) for deep venous thrombosis was done 24 hrs preoperatively 24 hrs, 72 hrs and 14 days postoperatively.
World Thrombosis Day is dedicated to educating people about the risk factors, signs, and symptoms of thrombosis.