The interface sign: a computed tomographic sign for distinguishing pleural and intra-abdominal fluid.

Abstract

On computed tomographic scans of the upper abdomen the interface sign can help distinguish pleural and intra-abdominal fluid readily and accurately. A hazy interface between the fluid and liver or spleen is characteristic of pleural fluid. A sharp interface is characteristic of ascites. The interface sign has proved to be accurate in 30 consecutive cases.