Increase in fluid formation and/or absorption in the pleural space.  The pathology is dependent on aetiology and divided into transudates and exudates.

Exudate (protein >35g/L) due to increased microvascular permeability 

- Malignancy e.g. metastatic carcinoma, mesothelioma

- Infection e.g. TB, parapneumonic, empyema

- Inflammation e.g. SLE, RA, post-CABG, benign asbestos effusion and drugs

Transudate (protein <35g/L) due to hydrostatic pressure or osmotic pressure:

- Cardiac e.g. LVF, mitral stenosis, constrictive pericarditis

- Renal e.g. peritoneal dialysis, Nephrotic syndrome

- Liver e.g. cirrhosis, ascites, hypoalbuminaemia

Trachea displaced away from effusion, reduced chest movement on affected side, stony dull percussion, reduced vocal fremitus, reduced breath sounds

Imaging: Chest X-Ray ultrasound, CT chest

Pleural Fluid: Diagnostic aspiration 

Pleural Biopsy: e.g. Abram’s needle, radiologically guided, VATs

Fluid Samples: LDH and protein, M,C&S, AFB and TB culture

Treat underlying cause

Therapeutic aspiration of 1-1.5L can be performed for symptomatic effusions

In some cases a chest drain may be needed.

Breathlessness, empyema