Definition of Pleural fluid Gram stain:

The pleural fluid Gram stain is a test to diagnose bacterial infections in the lungs.

How the test is performed:

Pleural fluid is found in the space around the lungs. In a variety of diseases, an abnormal amount of pleural fluid builds up in the lungs.

A sample of the pleural fluid is needed for this test. For information on how the sample is obtained, see: Thoracentesis

The fluid sample is placed onto a microscope slide and mixed with a violet stain (called a Gram stain). A laboratory specialist uses a microscope to look for bacteria on the slide. If bacteria are present, the color, number, and structure of the cells are used to identify the specific organism.

How to prepare for the test:

How the test will feel:

See: Thoracentesis

Why the test is performed:

The test is performed when the health care provider suspects an infection of the pleural space, or when a chest x-ray reveals an abnormal collection of pleural fluid.