Superior vena cava syndrome as a cause of pleural effusion.

The development in the postoperative period of the superior vena cava syndrome resulted in a persistent right-sided, transudative pleural effusion. It appears that the increased systemic venous pressure from left innominate thrombosis leading to superior vena cava obstruction in association with chest tube drainage connected to suction (increased intrapleural negative pressure) produced hydrostatic imbalances that resulted in increased pleural fluid formation and collection.