External accumulation of radionuclide in hepatic hydrothorax.

Hepatic hydrothorax is a complication in approximately 5% of patients with cirrhosis. Ascites is almost always present and helps to suggest the correct diagnosis. However, when ascites is absent, radionuclide imaging has proven to be helpful in establishing that the pleural effusion originated from ascitic fluid. When pleural fluid is rapidly removed, such as by thoracostomy tube drainage, the radioisotope may accumulate outside the thorax and produce a negative scan of the chest. When the radionuclide scan is nondiagnostic and the pleural space is being rapidly drained, the pleural fluid collecting system should always be imaged before rejecting a diagnosis of hepatic hydrothorax.