Pleuroperitoneal communication associated with malignant ascites. A potential cause for new pleural effusion suggestive of pulmonary embolism.

A patient with metastatic gastric carcinoma and malignant ascites developed sudden-onset dyspnea secondary to a new large left pleural effusion. A radionuclide lung scan performed for suspected pulmonary embolism was indeterminate. Scintigraphy performed following intraperitoneal administration of Tc-99m sulfur colloid subsequently demonstrated rapid accumulation of activity in the left pleural space, indicating the presence of a pleuroperitoneal communication. In a patient with known or suspected ascites, a new pleural effusion, and an indeterminate lung scan, peritoneal scintigraphy may identify the origin of the effusion and obviate the need for further invasive evaluation for possible pulmonary embolism.