What is the workup if you hear rales (crackles) on lung exam?

Workup for Rales on Lung Examination

When you hear rales on lung exam, immediately obtain a chest X-ray to differentiate between cardiac, infectious, and interstitial causes, while recognizing that rales alone are neither sensitive nor specific for any single diagnosis. 1

Initial Clinical Assessment

Critical First Steps

• Ask the patient to cough, then re-auscultate – persistent rales after coughing are more clinically significant than those that clear, particularly when evaluating for heart failure 2
• Obtain vital signs including oxygen saturation by pulse oximetry, heart rate, blood pressure, respiratory rate, and temperature 1
• Assess for accompanying signs of fluid overload (elevated jugular venous pressure, hepatomegaly, peripheral edema) versus infection (fever, productive cough) 1, 2

Physical Examination Priorities

• Characterize the rales: note whether they are fine/dry "Velcro-type" crackles (suggesting interstitial disease) versus coarse/wet crackles (suggesting fluid or secretions) 3
• Document the distribution: bilateral basilar rales suggest heart failure, while unilateral or focal rales suggest pneumonia 1
• Cardiac examination: listen for S3 gallop, assess jugular venous pressure, check for peripheral edema 1
• Note patient age: in patients over 65 years, age-related crackles occur in 34% of those aged 65-79 and 70% of those over 80, even without cardiopulmonary disease 4

Essential Diagnostic Testing

Mandatory Initial Tests

• Chest radiograph is required to establish the diagnosis and differentiate between pneumonia, heart failure, interstitial lung disease, and other causes 1
• Complete blood count to assess for leukocytosis (infection) or leukopenia (severe sepsis) 1
• Basic metabolic panel including renal function 1
• Arterial blood gas or pulse oximetry to assess oxygenation and respiratory adequacy 1

Condition-Specific Testing

If heart failure is suspected (rales with elevated JVP, edema, S3 gallop):

• B-type natriuretic peptide (BNP): use cutoff of 100 pg/mL for BNP or 300 pg/mL for NT-proBNP, though levels may be normal in "flash" pulmonary edema 1
• Echocardiography to assess left ventricular function and filling pressures 1
• ECG to evaluate for acute ischemia or arrhythmia 1

If pneumonia is suspected (rales with fever, cough, infiltrate on X-ray):

• Sputum Gram stain and culture if patient can produce adequate specimen 1
• Blood cultures if patient requires hospitalization 1
• Consider specific pathogen testing based on epidemiologic clues (travel history, exposures, immunocompromised state) 1

If interstitial lung disease is suspected (fine "Velcro" crackles at lung bases):

• High-resolution CT chest is the next step after chest X-ray shows interstitial changes 3
• Pulmonary function tests including diffusion capacity 3
• Consider autoimmune serologies if systemic disease suspected 3

Critical Diagnostic Pitfalls

Common Errors to Avoid

• Do not assume all rales indicate fluid overload – pneumonia, interstitial disease, and age-related changes are equally common explanations 2, 4
• Do not rely on rales alone to diagnose or exclude heart failure – they lack both sensitivity and specificity; the European Society of Cardiology emphasizes that rales are non-specific and not a sensitive marker for congestion 1, 2
• Do not withhold fluid resuscitation in septic patients solely because rales are present – if pneumonia is confirmed, rales may reflect the infectious process itself rather than fluid overload 2
• In elderly patients (>65 years), recognize that age-related crackles are extremely common (34-70% prevalence) and may not indicate pathology 4

Algorithmic Approach Based on Clinical Context

If rales + elevated JVP + peripheral edema + S3 gallop:

• Suspect heart failure → obtain BNP, chest X-ray, ECG, echocardiogram 1, 2

If rales + fever + productive cough + leukocytosis:

• Suspect pneumonia → obtain chest X-ray, consider sputum culture, blood cultures if severe 1, 2

If fine "Velcro" crackles at bases + progressive dyspnea:

• Suspect interstitial lung disease → obtain chest X-ray, then high-resolution CT if abnormal 3

If rales in elderly patient without other symptoms:

• Consider age-related crackles → document baseline, follow clinically, investigate only if symptoms develop 4