<Li> Clear straw - colored: If transudative, no further analysis needed . If exudative, additional studies needed to determine cause (cytology, culture, biopsy). </Li> <Li> Cloudy, purulent, turbid: Infection, empyema, pancreatitis, malignancy . </Li> <Li> Pink to red / bloody: Traumatic tap, malignancy, pulmonary infarction, intestinal infarction, pancreatitis, trauma . </Li> <Li> Green - white, turbid: Rheumatoid arthritis with pleural effusion . </Li>

The pleural cavity is the part of the thoracic cavity closely associated with these organs