Prophylactic treatment with 40 mg of enoxaparin subcutaneously per day safely and effectively reduces the risk of venous thromboembolism in patients with acute medical illnesses.

Rivaroxaban was superior to enoxaparin for thromboprophylaxis after total knee arthroplasty, with similar rates of bleeding. (ClinicalTrials.gov number, NCT00361894.)

Patients with a first episode of idiopathic venous thromboembolism should be treated with anticoagulant agents for longer than three months.

Management of patients with suspected pulmonary embolism on the basis of pretest probability and results of ventilation-perfusion scanning is safe.