Pericardial fluid gram stain is a method of staining a sample of fluid taken from the sac surrounding the heart to diagnose a bacterial infection. The gram stain method is one of the most commonly used techniques for the rapid diagnosis of bacterial infections.
How the test is performed:
A sample of fluid will be taken from the sac surrounding the heart. Before this is done, some people may have a cardiac monitor to check for heart disturbances. Patches called electrodes are put on the chest, similar to during an ECG . You might have a chest x-ray or ultrasound before the test.
The skin of the chest is cleaned with antibacterial soap. A trained physician, often a cardiologist, inserts a small needle into the chest between the ribs and into the thin sac that surrounds the heart (the pericardium). A small amount of fluid is taken out.
You may have an ECG and chest x-ray after the procedure. Sometimes the pericardial fluid is taken during open heart surgery.
A drop of the pericardial fluid is placed in a very thin layer on a microscope slide. This is called a smear. A series of special stains is applied to the sample. This is called a gram stain. A laboratory specialist looks at the stained slide under the microscope, checking for bacteria.
The color, size, and shape of the cells help make it possible to identify the bacteria.