Deep vein thrombosis (DVT) and pulmonary embolism (PE) collectively make up the condition known as venous thromboembolism (VTE). The incidence of VTE is 10% to 20% in general medical patients, 20% to 50% in patients who have had a stroke, and up to 80% in critically ill patients. The extent of the problem is underestimated, possibly because DVT and PE are often clinically silent. It is estimated that as many as 30% of patients hospitalized with VTE develop long-term post thrombotic complications. Hospital stays are shorter, which means that the majority of symptomatic thromboembolic complications in surgical patients occur after hospital discharge.