Transudative pleural effusions are characterized by what fluid properties?

Transudative pleural effusions are characterized primarily by their fluid properties, which include low protein content and a low number of inflammatory cells. The correct choice indicates that the fluid protein concentration in transudative effusions is less than 50% of the serum protein level. This is consistent with the pathophysiology of transudative effusions, which typically arise from systemic conditions that alter hydrostatic or osmotic pressure, rather than from local inflammation or infection.

To provide context, the other options describe characteristics associated with exudative pleural effusions or are incorrect interpretations of transudative properties. High protein content and inflammatory cells would be indicative of an exudate, which is often seen in infections, malignancy, or inflammatory processes. The presence of bacteria and pathogens would also suggest an exudative process, such as an infection leading to empyema, rather than the systemic issues that cause transudative effusions. Lastly, stating that transudative effusions only occur in the presence of malignancy is inaccurate, as transudative effusions can be linked to congestive heart failure, cirrhosis, or nephrotic syndrome, none of which are necessarily malignancies. Thus, recognizing the correct fluid properties