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This section introduces venous thromboembolic disorders, their incidence, prevalence, classification and risk factors
Formation of a blood clot – a thrombus – within a vein is known as venous thrombosis. Venous thrombosis can occur in any vein, but the most common manifestation is DVT, which occurs predominantly in the large veins in the leg.1,2 A DVT may form without a known reason, but the risk is higher (for example):
Deep vein thrombosis
If part or all of a DVT or other thrombus breaks away from the blood vessel wall and travels through the venous blood system, it is known as an embolus.2
Collectively, DVT and PE are known as VTE.
VTE is a major healthcare problem worldwide
VTE is a major cause of death. European data for 20073
AIDS, acquired immunodeficiency syndrome
Although the annual incidence of VTE is estimated at approximately 1 in 1000 of the population,6,7 certain groups are at considerably higher risk. For example, routine screening of patients in clinical trials showed the DVT frequency without prophylaxis to be:
Approximately half of diagnosed venous thromboembolic events are classed as provoked (caused by a known risk factor or factors), the other half are unprovoked (idiopathic), meaning that the cause is not known7,8,10
Among the reversible risk factors, surgery – especially major orthopaedic surgery involving the lower limbs and major surgery for cancer – acute medical illness, often involving immobilization, and pregnancy are major risk factors for VTE.