What is the recommended workup for a patient with suspected bronchiectasis?

Bronchiectasis Workup: A Comprehensive Diagnostic Approach

The essential workup for suspected bronchiectasis requires a thin-section CT scan to confirm the diagnosis, followed by a minimum panel of tests including sweat test, lung function, immunological tests, and lower airway bacteriology to identify underlying causes. 1

Initial Diagnostic Imaging

1. Baseline Chest X-ray

   • Should be performed in all patients with suspected bronchiectasis 1
   • Relatively insensitive but often first imaging obtained for respiratory symptoms 1
   • May show dilated bronchi but has limited sensitivity for bronchiectasis

2. Thin-Section CT Scan

   • Gold standard for confirming bronchiectasis diagnosis 1
   • Should be performed during clinically stable disease for optimal diagnostic accuracy 1
   • Diagnostic CT features include:
     • Bronchoarterial ratio >1 (internal airway lumen vs adjacent pulmonary artery)
     • Lack of airway tapering
     • Airway visibility within 1cm of pleural surface or touching mediastinal pleura 1
   • Use volumetric thin-slice CT with dose reduction techniques where available 1

When to Suspect Bronchiectasis

Consider investigation for bronchiectasis in patients with:

• Persistent production of mucopurulent or purulent sputum 1
• Rheumatoid arthritis with chronic productive cough or recurrent chest infections 1
• COPD with ≥2 exacerbations annually and previous P. aeruginosa culture 1
• Inflammatory bowel disease with chronic productive cough 1
• Recurrent respiratory infections 2

Minimum Panel of Tests

After confirming bronchiectasis on CT, the following tests should be performed 1, 2:

1. Sweat test (to rule out cystic fibrosis)
2. Lung function tests (in patients who can perform spirometry)
3. Full blood count
4. Immunological tests:
   • Total IgG, IgA, IgM, IgE levels
   • Specific antibodies to vaccine antigens
5. Lower airway bacteriology (sputum culture)
   • Common pathogens: H. influenzae, S. aureus, S. pneumoniae, P. aeruginosa 1
   • Mucoid Pseudomonas suggests cystic fibrosis
   • Aspergillus suggests allergic bronchopulmonary aspergillosis
   • Mycobacterium avium complex suggests NTM infection 1

Additional Targeted Investigations

Based on clinical presentation, consider 1, 2:

1. In-depth immunological assessment (consult with immunologist)

   • Particularly for suspected immunodeficiency syndromes
   • Common variable immunodeficiency may require Ig replacement therapy 1

2. Diagnostic bronchoscopy with bronchoalveolar lavage

   • For patients with localized disease to rule out foreign bodies/obstructive lesions
   • For patients who cannot expectorate sputum
   • For suspected NTM infection

3. Tests for specific conditions:

   • Allergic bronchopulmonary aspergillosis: Aspergillus-specific IgE, total IgE, skin testing
   • Primary ciliary dyskinesia: Nasal nitric oxide measurement, ciliary beat frequency/pattern
   • Alpha-1 antitrypsin deficiency: Serum alpha-1 antitrypsin level
   • Gastroesophageal reflux disease: 24-hour pH monitoring, impedance studies
   • Rheumatoid arthritis: Rheumatoid factor, anti-CCP antibodies
   • Inflammatory bowel disease: Fecal calprotectin, colonoscopy

4. In high-prevalence settings:

   • Tuberculosis testing
   • HIV testing 1

Diagnostic Pitfalls and Caveats

• CT findings alone may not be pathognomonic for specific etiologies 1
• Bronchoarterial ratio correlates with age; consider using lower threshold (>0.8) in children/adolescents 1
• Bronchiectasis may be idiopathic in up to 38% of cases despite thorough evaluation 3
• Perform imaging during clinically stable disease to avoid false positives during acute infections 1
• Certain CT distributions may suggest specific etiologies but require clinical correlation 1

Importance of Identifying Underlying Cause

A systematic search for underlying causes is crucial as it may identify conditions requiring specific treatment:

• Cystic fibrosis requires referral to specialty clinic
• Common variable immunodeficiency requires Ig replacement therapy
• Allergic bronchopulmonary aspergillosis requires corticosteroid treatment
• Recurrent aspiration may require intensive gastric acid suppression 1

By following this structured approach to bronchiectasis workup, clinicians can confirm the diagnosis and identify potentially treatable underlying causes, leading to improved patient outcomes and quality of life.