Pleural fluid smear is a laboratory procedure to check for tiny organisms or abnormal cells in the fluid found in the space around the lungs.

A health care provider examines a sample of pleural fluid under the microscope. If the smear detects organisms, other methods may be used to identify those organisms.

The sample is obtained through a procedure called thoracentesis. For information about this test and its risks, see: Thoracentesis

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.

Normally, no organisms are present in the pleural fluid.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Positive results may indicate that microorganisms or cancer cells are present. Other tests can help identify the specific type of infection or cancer.

See: Thoracentesis