Massive venous thrombosis of the extremities.
Massive venous thromboses of the extremities, although uncommon, are responsible for many of the long-term sequelae associated with venous disease. The charts of all patients with a diagnosis of iliofemoral venous thrombosis or subclavian vein thrombosis over a 6-year period were reviewed. There were 59 patients with iliofemoral venous thrombosis and 18 patients with subclavian vein thrombosis. Iliofemoral venous thromboses were three times more common, showed the classic leftsided predominance, and were more likely to be idiopathic. Subclavian vein thromboses showed no side or sex predilection and were due to anatomic abnormalities, intravenous lines, or radiation. Iliofemoral venous thrombosis showed poor response to lytic therapy, whereas subclavian vein thromboses were effectively lysed in those patients in whom it could be used. Massive venous thromboses of the extremities, although similar in presentation, have different characteristics depending upon the extremity affected. The cause, frequency, and response to treatment differ, which could ultimately influence outcome and the severity of postphlebitic symptoms.