Deep vein thrombosis (DVT) and acute pulmonary embolism (PE) are two manifestations of the same disorder, venous thromboembolism (VTE). DVT of the lower extremity, which will be discussed here, is subdivided into either distal (calf vein) or proximal (popliteal, femoral, or iliac vein) thrombosis. Proximal vein thrombosis is of greater importance clinically, since it is more commonly associated with serious, chronic disease (eg, active cancer, congestive failure, respiratory insufficiency, age >75), whereas distal thrombosis is more often associated with transient risk factors (eg, recent surgery, immobilization, travel) . As a further example, over 90 percent of cases of acute PE are due to emboli emanating from the proximal, rather than the distal (ie, below the knee), veins of the lower extremities, and the mortality rate of proximal DVT is higher than that of distal DVT .
VTE is an important cause of morbidity and mortality, particularly in hospitalized patients. PE is the cause of death or a major contributing factor in up to 16 percent of patients who die in the hospital. However, in some series, the diagnosis of PE is suspected before death in less than one-third of patients. It is therefore important to have a high index of suspicion for the presence of VTE and to initiate appropriate diagnostic tests and therapy. Primary prophylaxis with pharmacologic agents and/or mechanical methods should be used in patients with moderate to high risk of venous thromboembolism . This subject is discussed separately. (See "Prevention of venous thromboembolic disease in surgical patients".)
Deep vein thrombosis of the upper extremity is discussed separately. (See "Primary (spontaneous) upper extremity deep vein thrombosis" and "Catheter-related upper extremity venous thrombosis".)
Ancillary information — Because of the complexity of the issues surrounding diagnosis, screening, prevention, and treatment of VTE, we have provided the reader with an overview that can serve as a general introduction to all of the issues surrounding this subject. (See "Approach to the diagnosis and therapy of lower extremity deep vein thrombosis".)
More specific information on each of the aspects of this disorder is presented separately, as follows: