Pleural Effusion

Exam Cram

• Pleural effusion refers to fluid in the pleural space- between the lung and pleural sack it sits in

• The level of protein in the effusion fluid distinguishes its cause

• Diagnosis: chest XR or CT

• Management: tap a small sample for analysis, may require chest drain for definitive management

Outline

Background

• Pleural effusion is a common non specific presentation on the acute take that requires investigation for an underlying cause

• Once drained pleural effusions also have a high recurrence rate

• Isolate pleural effusions are concerning for malignancy and in the context of infection can represent an empyema

Assessment

History

• Malignant: insidious onset, shortness of breath, reduced exercise tolerance, weight loss

• Infective: persistent cough, fevers despite antibiotics for chest infection

• Inflammatory: background of inflammatory conditions  (SLE, Sjogren's, SS; RA) 

Examination

• Usually unilateral at base (can be bilateral)

  • Reduced air entry

  • Stone-y dull percussion

  • Reduced air entry on ausculatation

  • Reduced vocal resonance

Investigations

• Chest XR +- CT-Thorax to visualise

• Ascitic tap +- drain: look for transudate vs exudate, microscopy

• Investigate underlying cause: 

  • CTCAP ? malignancy

  • Sputum culture ?infection

  • UA ?proteinuria (nephrotic)

Diagnosis

Diagnostic criteria: usually made on imaging (Chest XR or CT)

Differentials: 

• Area of reduced air entry + dullness to percuss: bronchial or pulmonary malignancy, pulmonary infarction, atelectasis, consolidation (pneumonia)

• Consolidation on chest XR: pneumonia, malignancy

Classification: 

• Fluid type

  • Serous fluid

    • • Low protein: transudate - liver, heart, kidney failure

      • High protein (exudative)

        • • • Infective (purulent)- empyema

            • Tumour- mesothelioma, lung cancer, secondary lung mets

            • Inflammatory- e.g. Rheumatoid Arthritis 

  • Blood: haemothorax

  • Lymph: chylothorax

• Location

  • Bilateral- more likely to be transudative (heart, kidney, liver failure)

  • Unilateral- left (colorectal, ovarian cancer)

Management

A pleural effusion is not a sufficient diagnosis, the cause should be investigated. 

Acute

1. Aspiration: large volume vs drain

2. IV antibiotics if febrile/ signs of infection

3. Management dictated by underlying cause:

   1. Ascitic tap results- protein, LDH, pH, microscopy & culture

   2. Consider CT-CTAP

Types of Pleural Effusions

Exudative

Malignancy

• Ascitic tap: high protein & LDH, normal pH; microscopy may show malignant cells

• Presentation: insidious reduced exercise tolerance, anaemia + raised platelets, mesothelial thickening of imaging

• Management: can be managed with large volume aspiration & respiratory OP FU to repeat imaging; CTCAP ?source

Infection- Empyema

• Ascitic tap: high protein & LDH, pH < 7.2; microscopy should grow organism

• Presentation: post pneumonia, failing antibiotics- unwell

• Management: chest drain + IV antibiotics (based off growth)

Inflammatory

• Ascitic tap: high protein & LDH, normal pH & microscopy

• Presentation: insidious reduced exercise tolerance with PMH of inflammatory conditions  (SLE, Sjogren's, SS; RA) 

• Management: large volume aspiration, manage underlying cause, consider duiretics

Transudative

These are caused by low albumin (protein) states. Typically caused by vital organ failure but other causes exist:

• Vital organ failure

  • Congestive Heart Failure (CHF) 

  • Liver Cirrhosis 

  • Nephrotic Syndrome

• Hypoalbuminaemia 

  • Chronic disease, malnutrition, malabsorption

  • Iatrogenic: IVF + frailty

Ascitic Tap: low protein & LDH, normal pH, nil microscopy

Management: medical diuresis

Everything Else

Chylothorax

• Triglyceride > 1.2, 99% sensivity & specificity for chylothorax

• Assocaited with damage to thoracic duct from trauma or recent surgery

Haemothorax 

Causes

• Traumatic

• Non traumatic (medical)

Management: traumatic chest drain (surgery)

Peritoneal fistula

• Presentation: dialysis patient who develops pleural effusion

• Pleural fluid has high glucose or triglycerides

• This suggests a peritoneal dialysis source, which uses a high glucose

Oesophageal Rupture

• Presentation: chest pain, vomiting, pneumomediastinum/ pleural effusion

• Pleural fluid: exudate (high protein) with raised pleural amylase

Disease Cycle

First Presentation

• History, examination, observations 

• Investigations

  1. CXR- visualise

  2. Ascitic tap

     • Protein, LDH, pH, microscopy, culture & sensitivity

  3. FBC ?anaemia, U&Es ?AKI, CRP ?infection, LFTs ?liver mets

  4. UA: ?proteinuria ?nephrotic syndrome

  5. CTCAP: rule out malignancy, consider PSA/ mammogram

• Management

  1. Large volume aspiration vs chest drain

  2. Oxygen as requried

  3. IV Antibiotics if signs of infection- may require 6 weeks for empyema via PICC

  4. Respiratory discussion

Admission

Indication for admission:

• • Hypoxic

  • New diagnosis awaiting investigation for cause

  • High symptom burden & not coping at home

• Usually respiratory admission (Gen Med)

• If traumatic: general surgery

• Cardiothoracic if require surgical management

• Infectious diseases or rheumatology can provide consults based on underlying cause

Underlying cause

Malignancy

• Respiratory MDT- ideally with cancer sample:

  • Pleural aspirate

  • Bronchoscopy biopsy

  • CTCAP ?metastasis

• Plan as per MDT- dc +- treatment options

Empyema

• Pleural aspirate grow organism to dictate antibiotics

• Discussion with infectious diseases

• 4-6w IV antibiotics with PICC- outpatient IV antibiotics candidate

Inflammatory

• Discussion with rheumatology

• ?Duiresis

• ?Modify underlying disease modifying medical regime

Transudative

• Discussion with gastroenterology, renal or cardiology as per underlying cause

• Duiresis

Recurrent pleural effusions

• Chest drain + pleurodesis (mesothelioma)

• Video assisted procedure (VATs) by cardiothoracic

  • Chest drain

  • Partial pleurectomy

• Extra pleural pneumectomy

References and Resources

Page written in 2024, updated in 2026.