Pleural Effusion

Collection of fluid within the pleural space between the parietal and visceral pleura








Pleuritic chest pain

Weight loss, rash, abdominal swelling, peripheral oedema



On inspection:

Scars/dressing/biopsy/aspiration needle mark/radiotherapy tattoos

Supplementary oxygen
Walking aids
May have clubbing depending on underlying cause
On examination:

Reduced expansion
Trachea displaced away from side of the effusion

Apex beat shifted away from the side of the effusion
Stony dull percussion note
Decreased vocal resonance
Reduced air entry/breath sounds
Bronchial breathing may be present above the effusion


Comment on presence/absence of respiratory failure: oxygen, cyanosis, CO2 retention flap, bounding pulse


Comment on presence/absence of pulmonary hypertension/cor pulmonale: raised JVP, right ventricular heave, loud second heart sound, peripheral oedema


Comment on possible cause

Signs that indicate the underlying cause:

Malignancy: clubbing, cachexia, lymphadenopathy, tar staining, radiation burns, Horner’s syndrome, small hand muscle wasting, hypertrophic pulmonary osteoarthropathy (HPOA), evidence of chemo eg. hair loss, resection scars, mastectomy scars

Infection: chest drain scar, iv cannula, iv antibiotics, febrile
CCF: raised JVP, sacral oedema and peripheral oedema, bibasal crepitations
Chronic liver disease: palmar erythema, bruising, jaundice, spider naevi, gynaecomastia etc.
CKD: AV fistula, peritoneal dialysis, CBG monitoring marks, renal biopsy scar, scar from neck lines etc.


Connective tissue disease: cutaneous signs of lupus, systemic sclerosis, rheumatoid arthritis (peripheral symmetrical deforming polyarthropathy)


Sarcoidosis: lupus pernio


Yellow Nail Syndrome: yellow nails, lymphoedema, features of bronchiectasis as well as pleural effusion


Dressler’s syndrome: CABG scar





Differential Diagnosis for examination findings:


Lower Lobe collapse

Lobectomy (would expect to see a scar)

Raised hemidiaphragm eg. phrenic nerve palsy, hepatomegaly

Basal consolidation

Pleural thickening eg. pleural plaques

Mitotic mass



Causes of pleural effusion:

Transudates or exudates as defined by Lights criteria


Protein concentration:

>30g/dl= exudate

<30g/dL = transudate


Light’s criteria:

One out of 3 criteria for exudate (sensitive but not specific):

  1. Pleural albumin/serum albumin >0.5
  2. Pleural LDH/serum LDH >0.6
  3. Pleural LDH >2/3rds upper normal limit of serum LDH


Transudates (usually bilateral):



Nephrotic syndrome


Meigs syndrome



Exudates (usually unilateral):

Malignancy (primary bronchial/pleural, secondaries from breast/renal/pancreas/ovaries)

Infection: Parapneumonic, TB effusion. Can cause empyema (pH <7.2)



Connective tissue disease: Rheumatoid Arthritis, SLE, Systemic sclerosis


Dresslers (post CABG)

Drugs (nitrofurantoin, methotrexate, amiodarone, phenytoin etc.)

Yellow Nail syndrome

Asbestos effusion

Oesophageal rupture





Bedside tests:

ECG (right heart strain)

ABG (respiratory failure)

Urine dipstick (proteinuria)


Laboratory tests:

Bloods- FBC. U+E, LFT, CRP/ESR, LDH, clotting, amylase, lipid profile, TFTs, RF, ANA, ANCA, complement if suspicion of connective tissue disease

Blood cultures

Sputum gram stain, culture and sputum for AFBs

Pleural fluid analysis (USS guided aspiration):

  • Appearance (clear/straw, yellow/turbid, milky, blood)
  • Biochemistry: LDH, protein, pH, glucose, amylase, triglycerides, cholesterol
  • Microbiology: gram stain, cell count, culture, AFB culture
  • Cytology: for malignant cells
  • Immunology: Rheumatoid factor, ANA, complement




  • Effusion must be approximately 300ml to be detected on xray
  • Dense opacity with associated fluid level (meniscus sign)
  • Blunting of costophrenic angle(s)
  • Mediastinal shift (tracheal deviation) if fluid levels >1000mls
  • Evidence of underlying cause

USS chest – loculated effusion, to insert drain/sample fluid

Contrast enhanced CT thorax: detect small effusions, look for the underlying cause

Bronchoscopy, thoracoscopy

Pleural biopsy






Depends on the underlying cause: antibiotics for parapneumonic effusion, diuretics for CCF etc.

Supportive: oxygen and IV hydration, chest physio

Therapeutic chest drain insertion for empyema, symptomatic effusion, malignant effusion, haemothorax

If effusions recurrent:

  • Continuous tube thoracostomy
  • Pleurodesis- most commonly with malignant effusions. Can be done medically with talc or surgically with video assisted thoracoscopic surgery



Written by Dr Amna Shah

Edited by Dr Sarah Kennedy


Resources used to write this document are listed in the references section of this webpage