Pleural fluid gram stain

Alternative names:

gram stain of pleural fluid

How the test is performed:

A sample of pleural fluid obtained by needle aspiration is applied in a very thin layer to a microscope slide. The specimen is stained with a violet stain known as a gram stain, and then examined under the microscope for the presence of bacteria. The color, number, and morphologic appearance of the cells help make it possible to identify the organism.

How to prepare for the test:

Adults:
It is important not to cough, breathe deeply, or move when the fluid sample is being taken. There is no other special preparation for the test.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

How the test will feel:

The specimen is obtained by a needle aspiration of the pleural space. The chest is cleansed with antibacterial soap. A needle is placed between the ribs and a small amount of fluid is withdrawn from the chest. There will be pressure and some localized pain associated with the test. A chest X-ray may follow the test to be sure the lung tissue was not affected by the test.

Why the test is performed:

The test is performed when infection of the pleural space is suspected or when an abnormal collection of pleural fluid is noticed by chest X-ray.