Analysis of pleural fluid: Differentiating transudate from exudate

Abstract

Introduction: Pleural fluid is defined as the fluid that is found between the two layers of pleura, (i.e. the parietal and visceral pleura) the membranes which line the cavity and surround the lungs. Normally, 10-20ml of pleural fluid, similar in composition to plasma but lower in protein ( over the layers of pleura, facilitating the movement between lungs and chest wall. The pleural fluid enters the systemic capillaries in the parietal pleura and exits via the parietal pleural stoma and lymphatics. (1) Pleural fluid accumulates when too much fluid enters or too little fluid exits the pleural cavity. Pleural fluid analysis is used to diagnose the cause of accumulation of pleural fluid in the chest cavity (Pleural effusion). Pleural effusion may be Transudative or Exudative. Analysis is done in three broad spectrums (1) Biochemical analysis (2) Microbiological analysis (3) Clinical pathology or cytology analysis. Materials and Methods: Pleural fluid is obtained by Thoracocentesis. Thoracocentesis or pleural tap is an invasive procedure to remove fluid or air from the pleural space for diagnostic or therapeutic purposes. The fluid obtained is sent for analysis. Pleural fluid analysis is a group of tests used to diagnose the cause of fluid build-up such as CHF, Cirrhosis, Infection etc. Result: Study shows that pleural effusions are common among 40-60 years of age group with a slight male predominance. The present study suggests that exudative effusions are more common than transudative effusions with a percentage of 61%. Conclusion: Pleural fluid analysis helps in diagnosing the etiology of the effusion based on the appearance and biochemical parameters. The common etiology for pleural effusion reported in India is Tuberculosis. WHO statistics shows India accounted for 27% of the total new infections in 2017, which is the highest among the top 30 high TB burden countries in the world. Keywords: Exudative, Pleural fluid, Transudative, Thoracocentesis.