Venous thromboembolism, including deep venous thrombosis (DVT) and pulmonary embolism, represent a major source of morbidity and mortality today. Incidence of DVT is estimated to be 56 to 160/100,000 population per year. Systemic anticoagulation with low molecular weight heparin or unfractionated heparin with initiation of oral vitamin K antagonist therapy has been shown to be beneficial in preventing pulmonary embolism and reducing extension and recurrence of DVT. The duration of anticoagulation following an episode of DVT is determined by the greatest predictors of recurrence. These include the presence of reversible risk factors, nonreversible risk factors, and no risk factors (idiopathic or unprovoked DVT). Short durations of anticoagulation are only appropriate for calf DVTs in patients with reversible risk factors. Patients with nonreversible risk factors, such as malignancy and certain inherited thrombophilias with a strong family history of venous thromboembolism will require lifelong anticoagulation. Those with proximal DVT due to reversible risk factors require 3 to 6 months of anticoagulation. Patients with idiopathic DVT require reassessment of risk-to-benefit ratio of hemorrhage from oral vitamin K antagonist therapy compared to reducing risk of recurrence and frequently require prolonged oral anticoagulant therapy. Monitoring with d-dimer and serial ultrasounds may offer an individualized approach to therapy.
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