Definition of Bronchiectasis in Adults
Bronchiectasis in adults is defined by the presence of permanent, irreversible bronchial dilatation on chest CT scan combined with characteristic clinical symptoms such as chronic cough, sputum production, and recurrent respiratory infections 1.
Radiological Criteria (Required for Diagnosis)
The diagnosis requires thin-section chest CT imaging to confirm bronchial dilatation, demonstrated by one or more of the following CT features 2:
- Bronchoarterial ratio >1 (internal airway lumen diameter compared to adjacent pulmonary artery)
- Lack of bronchial tapering as airways extend toward the periphery
- Airway visibility within 1 cm of the costal pleural surface or touching the mediastinal pleura
Important Imaging Considerations
CT should ideally be performed during clinically stable disease for optimal diagnostic accuracy and to serve as a baseline for future comparisons 2. The radiological findings alone are insufficient—the diagnosis requires correlation with clinical features.
Clinical Criteria (Required for Diagnosis)
Clinically significant bronchiectasis requires the radiological findings described above plus characteristic symptoms 1. The most recent 2025 ERS guidelines emphasize that both components must be present—radiological changes without symptoms do not constitute clinically significant disease requiring treatment.
Characteristic Clinical Features Include:
- Chronic productive cough with mucopurulent or purulent sputum
- Recurrent respiratory infections
- Dyspnea and fatigue
- Chronic respiratory symptoms that cannot be explained by other conditions
Key Diagnostic Principle
The definition is both radiological AND clinical—you cannot diagnose bronchiectasis based on imaging alone, nor can you diagnose it based on symptoms alone 1, 3. This dual requirement distinguishes clinically significant bronchiectasis from incidental radiological findings that may not require intervention.
Common Pitfall to Avoid
Do not diagnose bronchiectasis based solely on chest X-ray findings. While chest X-ray should be performed initially when bronchiectasis is suspected, CT scan is required to confirm the diagnosis 2. Chest X-rays lack the sensitivity and specificity needed for definitive diagnosis and may miss early or mild disease.
Exclusions from This Definition
This definition applies to non-cystic fibrosis bronchiectasis in adults. Separate guidelines exist for:
- Cystic fibrosis-related bronchiectasis
- Pediatric bronchiectasis
- Specific conditions like primary ciliary dyskinesia, allergic bronchopulmonary aspergillosis, and non-tuberculous mycobacterial disease (though the general definition still applies, these require syndrome-specific management) 1