Fungal Culture - Pericardial Fluid lab test is used as a diagnostic test to determine the cause of inflammation of the pericardium. In order words, it used to know whether there is accumulation of fluid around the heart, also known as pericardial effusion. Fluid accumulation usually happens for two main reasons - due to an imbalance of pressure within the blood vessels or due to an inflammation of the of the pericardium. In addition to this, additional testing can also include heads like pericardial fluid glucose, cytology, gram stain, etc.