Pleural Effusion
Key Points
- Unilateral pleural effusion requires further aetiological investigation, with pleural fluid analysis as the usual first investigative step
- All effusions in the context of pneumonic illness should be sampled to assess for the presence of complicated parapneumonic effusion (pH < 7.2) or empyema (frank pus)
- Ultrasound is a far more sensitive technique for the diagnosis of pleural effusion than chest radiography. In cases where initial ‘blind’ aspiration has failed, or in the presence of an anatomically complex collection, image guidance (ultrasound or computed tomography)
should be sought - Drainage of undiagnosed pleural effusions ‘to dryness’ is not recommended, as this makes further investigation techniques more dificult. In the case of a breathless patient, removal of 4-4.5 litres of pleural fui will usualy alleviate symptoms
- Pleural fluid cytology is positive in only 60% of malignant pleural effusions. A negative fluid cytology in the absence of another clear cause for pleural effusion should prompt further investigations via a respiratory specialist
