What are the typical examination findings and diagnostic tests for a patient with suspected pneumonia?

Examination Findings of Pneumonia

The most specific physical examination findings for pneumonia are dull percussion note and pleural rub, though their absence does not exclude the diagnosis; focal chest signs (crackles, diminished breath sounds, bronchial breathing) combined with abnormal vital signs (fever ≥38°C, tachypnea >25/min, tachycardia, hypoxemia) substantially increase pneumonia likelihood and warrant chest radiography for confirmation. 1

Highly Specific Physical Findings

The following findings, when present, strongly suggest pneumonia but have low sensitivity:

• Dull percussion note over affected lung regions is highly specific for consolidation 1
• Pleural rub (friction rub on auscultation) is highly specific for pneumonia 1
• Increased tactile fremitus indicates lung consolidation and is highly specific, though many patients with pneumonia will not demonstrate this finding 1
• Bronchial breath sounds heard over peripheral lung fields suggest consolidation 2, 3

Moderately Specific Focal Chest Signs

New focal chest signs increase pneumonia probability from 5-10% to 39% and include: 1

• Crackles (rales) in a discrete lung region, particularly when combined with breathlessness 2, 1, 3
• Diminished breath sounds in affected areas due to consolidation 1
• Asymmetric findings that localize to one lung region rather than diffuse bilateral findings 1

The combination of absence of runny nose with breathlessness and focal crackles/diminished breath sounds significantly increases pneumonia likelihood 1

Vital Sign Abnormalities

Abnormal vital signs correlate with disease severity and increase diagnostic probability:

• Fever ≥38°C (or hypothermia ≤36°C in severe cases) 2, 4, 3
• Tachypnea >25 breaths/min (or >20 breaths/min in some criteria) is particularly important and correlates with severity 2, 5, 3
• Tachycardia ≥100 beats/min 3
• Oxygen saturation <90% on room air indicates severe disease 2, 3
• Hypotension (systolic BP <90 mmHg) suggests severe pneumonia requiring hospitalization 5

The absence of ANY vital sign abnormalities substantially reduces pneumonia likelihood to where further evaluation may be unnecessary 6

Respiratory Symptoms and Signs

• New or worsening cough with or without sputum production 2, 5, 4
• Purulent or discolored sputum (particularly brown/rust-colored) suggests bacterial infection 2, 3
• Dyspnea or increased work of breathing 2, 5
• Pleuritic chest pain (sharp pain worsening with breathing) 5

Systemic Findings

• Altered mental status in elderly patients (≥70 years) with no other recognized cause 2, 5, 3
• Cyanosis indicates severe hypoxemia 3
• Chills and rigors suggest bacterial infection 5, 3

Diagnostic Algorithm Based on Examination

High Probability (Chest X-ray Mandatory)

If dull percussion note OR pleural rub is present, pneumonia is very likely and chest radiograph should be performed immediately 1

If fever ≥38°C PLUS tachypnea PLUS focal chest signs are present, pneumonia is highly likely and chest radiography should be performed immediately, with empiric antibiotics initiated if imaging cannot be performed promptly 1

Moderate Probability (Consider CRP Testing)

If focal chest signs are present without fever, measure C-reactive protein (CRP); if CRP >30 mg/L with focal signs, pneumonia probability increases substantially and chest radiography is indicated 2, 1

• CRP >30 mg/L combined with clinical findings increases diagnostic accuracy (area under curve 0.77-0.79) 2
• CRP <20 mg/L makes pneumonia less likely in primary care settings 2

Low Probability (May Defer Imaging)

If all vital signs are normal AND no focal consolidation signs are present, the likelihood of pneumonia is sufficiently low that chest radiography may not be necessary 1, 6

Laboratory Findings

• Leukocytosis (WBC >12,000/mm³) or leukopenia (WBC <4,000/mm³) 2, 4
• Elevated CRP >30 mg/L adds diagnostic value beyond clinical findings alone 2
• Procalcitonin does NOT add diagnostic value over symptoms, signs, and CRP 2

Special Population Considerations

Elderly patients (≥65 years) may present with pneumonia without classic findings and require higher clinical suspicion, often presenting with confusion, falls, or decompensation of chronic conditions rather than respiratory symptoms 1, 5

Critical Caveat

Clinical judgment alone has only moderate sensitivity (79%) and specificity (66%) for pneumonia diagnosis 3. There are no individual clinical findings or combinations that can definitively rule in pneumonia; chest radiography remains the gold standard for confirmation 1, 5, 6. However, clinical findings guide the decision of who requires imaging and the urgency of obtaining it.