What history and physical examination findings should be obtained when evaluating a patient with suspected pleural effusion?

History and Physical Examination of Pleural Effusion

Clinical History

Begin by obtaining a detailed occupational history, particularly documenting any asbestos exposure, as this is essential for both diagnosis and potential legal compensation. 1, 2

Key Historical Elements to Elicit:

Symptom Profile:

• Dyspnea (most common presenting symptom, initially on exertion) 1, 3
• Pleuritic chest pain (present in approximately 75% of patients with pulmonary embolism-related effusions) 1, 2
• Dry cough (predominantly non-productive) 1, 3
• Weight loss, fever, and night sweats (suggest malignancy or tuberculosis) 1
• Abdominal pain (lower lobe effusions may present this way, especially in children) 1

Temporal Pattern:

• Symptoms developing over many months suggest chronic processes like malignancy 1
• Spiking fever and lack of improvement after 48 hours of antibiotics in a pneumonia patient signals parapneumonic effusion 1
• Dyspnea disproportionate to effusion size strongly suggests pulmonary embolism 1, 2

Medication Review:

• Perform a comprehensive drug history using resources like the Pneumotox application, as tyrosine kinase inhibitors and numerous other medications cause exudative effusions 1, 2

Underlying Medical Conditions:

• Heart failure, cirrhosis, nephrotic syndrome, or dialysis (suggest transudative causes) 1, 2
• Recent pneumonia (parapneumonic effusion) 1, 4
• Known malignancy (metastatic disease) 1
• Immunodeficiency, tuberculosis exposure, or foreign body aspiration (in appropriate contexts) 1

Physical Examination

Unilateral pleural effusion is characterized by the triad of decreased chest expansion, dullness to percussion, and reduced or absent breath sounds on the affected side. 1

Systematic Examination Findings:

Respiratory Examination:

• Decreased or absent tactile fremitus on the affected side 1
• Dullness to percussion (earliest sign detectable with ~200 mL of fluid on chest radiograph) 4
• Reduced or absent breath sounds over the effusion 1
• Decreased chest wall expansion on the affected hemithorax 1

Assessment of Severity:

• Measure oxygen saturation (SpO₂): levels below 92% indicate severe disease requiring urgent intervention 1
• Respiratory rate and work of breathing: tachypnea and accessory muscle use suggest respiratory compromise 1

Signs Suggesting Specific Etiologies:

• Bilateral effusions with elevated jugular venous pressure and peripheral edema: congestive heart failure 1, 2
• Ascites, jaundice, and spider angiomata: cirrhotic effusion 1
• Cachexia and lymphadenopathy: malignancy 1
• Fever and signs of consolidation: parapneumonic effusion or empyema 1, 4

Additional Assessment:

• Hydration status (important in children and critically ill patients) 1
• Height, weight, and nutritional status 1
• Presence of scoliosis (can be detected and may complicate interpretation) 1

Clinical Decision-Making Based on History and Physical

If the clinical picture strongly suggests a transudate (bilateral effusions in a patient with heart failure, cirrhosis, hypoalbuminemia, or on dialysis), diagnostic thoracentesis is NOT required unless atypical features are present or the effusion fails to respond to treatment of the underlying condition. 1, 2, 5

Atypical features mandating thoracentesis even in presumed transudates include:

• Unilateral or markedly asymmetric bilateral effusions 2, 5
• Normal cardiac silhouette on chest radiograph 5, 4
• Fever, weight loss, or elevated inflammatory markers 4
• Progressive enlargement despite treatment 2, 5

Proceed directly to ultrasound-guided thoracentesis for:

• Any unilateral pleural effusion 2, 4
• Suspected parapneumonic effusion (fever with pneumonia) 1, 4
• Clinical suspicion of pulmonary embolism (pleuritic pain, dyspnea out of proportion to effusion size, effusion occupying <1/3 hemithorax) 1, 2
• Any diagnostic uncertainty 2, 4

Critical Pitfalls to Avoid

• Do not assume unilateral effusions in heart failure patients are cardiac in origin: 41% of acute decompensated heart failure admissions have unilateral effusions, and alternative etiologies (malignancy, infection) must be excluded 4
• Do not delay thoracentesis in febrile patients with effusion: early sampling is essential to prevent progression to empyema 5, 4
• Maintain high suspicion for pulmonary embolism: pleural fluid studies are not diagnostic for embolism, so clinical context (pleuritic pain, disproportionate dyspnea, small effusion) should trigger appropriate imaging 1, 2
• Always use ultrasound guidance for thoracentesis: this is now considered an extension of the physical examination and significantly reduces complications 2, 4