Pleural effusion resident survival guide

Jump to navigation Jump to search

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Twinkle Singh, M.B.B.S. [2]


Pleural effusion is defined as the presence of excessive fluid in the pleural cavity resulting from transudation or exudation from the pleural surfaces.


Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.

Common Causes



Initial Diagnosis

Shown below is an algorithm for diagnosing pleural effusion clinically according to an article published by Richard W. Light in New England Journal of Medicine.[1]

Characterize the symptoms:

Shortness of breath
Chest pain

Examine the patient:

❑ Asymmetrical chest expansion
❑ Dullness to percussion
❑ Decreased tactile fremitus
❑ Mediastinal shift

❑ Shift away from the effusion side in massive effusion
❑ Shift towards the effusion side in lobar bronchial obstruction
❑ Decreased breath sounds
Look for signs suggestive of specific etiology
Suspected causeSuggestive signs
Congestive heart failureDistended neck veins
S3 heart sound
Peripheral edema
Pulmonary embolismThrombophlebitis
Right ventricular heave
Hepatic causeSigns of liver failure
Weight loss
❑ Perform chest X-ray
If chest X-ray is equivocal, perform the following:

Chest ultrasonography OR
Lateral decubitus chest radiograph

Assess thickness of pleural effusion on USG or lateral decubitus chest X-ray
> 10 mm
< 10 mm
Perform diagnostic thoracentesis if
❑ No cause is known
Pleural infection is suspected
❑ Malignant effusion is suspected clinically

If dyspnoea is present at rest:

❑ Perform therapeutic thoracentesis
❑ Remove up to 1500 ml of fluid
❑ Rule out pulmonary embolism
If CHF is suspected clinically
If any cause is suspected clinically
❑ Treat the cause

If no cause is suspected clinically

❑ Observe
❑ Bilateral effusion
❑ Afebrile
❑ No chest pain
❑ Unilateral effusion OR
Fever present OR
Chest pain
❑ Trial of diuretics
❑ Perform thoracocentesis

Pleural Fluid Analysis

Shown below are the algorithms for diagnosing pleural effusion after thoracocentesis is done. Algorithm is adapted from the 2010 guidelines issued by British Thoracic Society.[2]

Pleural fluid aspiration
Analyze the appearance of pleural fluid.
Fluid appearanceSuspected cause
Putrid odourAnaerobic empyema
Food particlesEsophageal rupture
Bile stainedBilliary fistula
MilkyChylothorax or pseudochylothorax
Anchovy sauce like appearanceAmoebic abscess
Grossly bloodyMalignancy
Pulmonary embolism with infarction
Order tests

❑ Serum total protein
❑ Serum LDH
Pleural fluid tests
❑ Protein
❑ Glucose
❑ Gram stain
❑ Differential cell count
❑ Cytology

Apply Light's criteria
Pleural fluid protein divided by serum protein > 0.5
Pleural fluid LDH divided by serum LDH > 0.6
Pleural fluid LDH> 2/3 of upper limit of normal serum LDH
Pleural fluid is classified as an exudate if one or more of the above criteria are met.
Did pleural fluid tests reveal the cause?
❑ Treat the cause:
Heart failure
❑ Treat accordingly
Order additional tests
TestsSuspected cause
Culture and sensitivityInfection
AmylaseEsophageal rupture
ADATuberculosis (measured if pleural fluid lymphocytosis is present)
Cholesterol crystals
Chylothorax or pseudochylothorax
If additional tests did not reveal any cause:
❑ Perform contrast enhanced CT
If additional tests diagnosed the effusion:
❑ Treat accordingly
❑ Treat the cause if diagnosed
If no diagnosis found:
❑ Proceed with imaging guided pleural biopsy OR
No diagnosis found?
❑ Proceed with bronchoscopy (if bronchial obstruction is suspected clinically)
❑ Treat accordingly if diagnosed
No diagnosis found?
Diagnose as non specific pleuritis
Reconsider following causes

Pulmonary embolism

Heart failure
❑ Treat accordingly ifdiagnosed
Observation if no cause found

CT: Computerized Tomography


  • Do not aspirate bilateral pleural effusion in a clinical setting suggesting of a transudate, unless the effusion fails to respond to therapy.
  • Obtain detailed drug history, as some drugs can cause pleural effusion such as methotrexate, amiodarone, phenytoin, nitrofurantoin, beta-blockers.
  • Keep a high suspicion for pulmonary embolism in pleural effusion cases.
  • Aspirate pleural fluid with a fine bore (21 G) needle and a 50 ml syringe with ultrasound guidance.
  • Aspirate pleural fluid into a heparinised blood gas syringe if infection is suspected and pleural fluid pH is needed to be done.
  • Send some of the pleural fluid sample in blood culture bottles if infection is suspected, particularly for anaerobic organisms.
  • Centrifuge pleural fluid sample if aspiration is milky to distinguish between empyema and lipid effusions.
  • Interpretation of centrifuged sample:
Supernatant Interpretation
Clear Empyema (turbid fluid was due to cell debris)
Turbid Chylothorax or pseudochylothorax
Differential cell counts
Neutrophil predominant
Lymphocyte predominant (>50% lymphocytes)
Eosinophil predominant (≥ 10% eosinophils)
Cardiac failure
❑ Rheumatoid pleurisy
CABG effusion
❑ Air or blood in the effusion fluid
Parapneumonic effusion
❑ Benign asbestosis
Churg-strauss syndrome
Pulmonary infarction
❑ Parasitic infection
  • Consider following causes if pleural fluid pH is < 7.30:
* Malignancy
* Rheumatoid arthritis
* Esophageal rupture
* Tuberculosis
  • Interpret cytology report of pleural fluid as follows:
Result Interpretation
Inadequate sample No mesothelial cells detected
No malignant cells seen Sample is adequate; no atypical cells seen;malignancy is not excluded
Atypical cells Inflammatory or malignant cells; further investigation required
Suspicious malignancy Cells with few malignant features present; no definitive malignant cells present
Malignant Definite malignant cells detected; further immunocytochemistry required


  • Do not allow pleural aspirate to come in touch with local anesthetic or air if pleural fluid pH is needed to be measured.


  1. Light RW (2002). "Clinical practice. Pleural effusion". N Engl J Med. 346 (25): 1971–7. doi:10.1056/NEJMcp010731. PMID 12075059.
  2. Maskell N, British Thoracic Society Pleural Disease Guideline Group (2010). "British Thoracic Society Pleural Disease Guidelines--2010 update". Thorax. 65 (8): 667–9. doi:10.1136/thx.2010.140236. PMID 20685739.