Adequate anticoagulation treatment in patients with deep vein thrombosis reduces the risk of thrombus extension or embolization to less than 5%. Thrombolytic treatment may possibly prevent subsequent postthrombotic syndrome. Heparin is the initial treatment of choice for most patients with deep vein thrombosis. The dose is adjusted according to the results of tests such as the whole blood clotting time, thrombin clotting time, activated partial thromboplastin time or plasma heparin concentration. The most commonly used test is the activated partial thromboplastin time which should be maintained at 1 1/2 to two times the control level. Initially the test should be performed two to three times daily and when optimal adjustment has been established, clotting studies are required only at 24-hour intervals. In general, treatment with intravenous heparin should be continued for seven to ten days. Thereafter, for secondary prophylaxis, treatment with oral anticoagulants is carried out for six to eight weeks for symptomatic lower leg thrombosis, for twelve weeks in the case of proximal venous thrombosis and pulmonary embolism. Oral anticoagulant therapy with warfarin should be given overlapping the last few days of heparin with the dose adjusted to prolong the prothrombin time to 1.3 to 1.5 times control. Initially, the prothrombin time should be monitored weekly, thereafter at intervals of two to three weeks. If oral anticoagulant therapy is contraindicated, secondary prophylaxis with subcutaneous heparin given twice daily in doses sufficient to prolong the activated partial thromboplastin time to 1 1/2 times control is an effective and safe alternative. The major side effect of oral anticoagulant therapy, as well as that of heparin, is bleeding.(ABSTRACT TRUNCATED AT 250 WORDS)
