Initially, patients with deep vein thrombosis (DVT) should be treated with a 5- to 7-day course of heparin or low-molecular-weight heparin (LMWH). They can be administered LMWH as outpatients. Patients with extensive iliofemoral thrombosis, major pulmonary embolism, or concomitant medical illness, and those at high risk for bleeding, should be treated as inpatients. Thrombolytic therapy may be considered for patients with extensive iliofemoral thrombosis if there is no contraindication to the use of thrombolytic drugs. Oral anticoagulants can be started within 24 hours of the initiation of heparin or LMWH. Warfarin is started at a dose of 5 mg, and subsequent doses are given in amounts sufficient to achieve an international normalized ratio of 2.0 to 3.0. Inferior vena caval filters should be considered for patients with overt bleeding or for those at high risk for hemorrhage. Warfarin can be used for secondary prophylaxis in most patients. Patients in whom there are contraindications to the use of oral anticoagulants and patients in whom recurrent venous thromboembolism (VTE) develops while they are receiving therapeutic doses of warfarin can be safely and effectively treated with LMWH. Patients with idiopathic DVT should be treated with anticoagulants for at least 6 months. Those with calf DVT or proximal DVT that complicates surgery or medical illness can be treated with anticoagulants for 6 weeks and 3 months, respectively, provided that there are no ongoing risk factors for recurrent VTE. Oral anticoagulants are teratogenic and should be avoided by patients who are pregnant; unfractionated heparin or LMWH are safe alternatives. Unfractionated heparin, LMWH, and oral anticoagulants can be safely administered to nursing mothers.
