Venous thrombosis: prevention, treatment, and relationship to paradoxical embolization.

Deep venous thrombosis (DVT) is responsible for approximately 200,000 hospitalizations annually in the United States. DVT is easier and less expensive to prevent than to diagnose and treat. For every one million patients undergoing surgery who do receive prophylaxis against venous thrombosis, approximately $60 million will be saved in direct health care costs because effective mechanical and pharmacologic modalities are available to prevent most venous thrombi. The therapy for DVT should be based upon the anatomic extent of the thrombus as well as upon the patient's risk for pulmonary embolism, recurrent DVT, and chronic venous insufficiency. In patients with paradoxical embolism, a patent foramen ovale, occult leg vein thrombosis (particularly isolated calf vein thrombosis) is frequently present.