Investigations for and diagnosis of bronchiectasis
High-resolution computed tomography (HRCT) is the gold standard for diagnosis of bronchiectasis. Clinically significant bronchiectasis is diagnosed on HRCT when the bronchial diameter exceeds that of the adjacent vessel in a patient with symptoms of bronchiectasis. Children are more sensitive to ionising radiation; if an HRCT scan is considered in a child, consult with a paediatric specialist.
Chest X-ray is important for investigating causes of chronic cough, but is usually not adequate to diagnose bronchiectasis. Chest X-ray may be normal in bronchiectasis.
Pulmonary function testing in bronchiectasis often reveals airflow obstruction; however, 48% of patients with bronchiectasis have normal spirometry and only 34% of patients have airflow obstruction.
Consider specific diagnostic testing for conditions associated with bronchiectasis, directed by the clinical findings (patient history and physical examination) and radiological appearances. If there are no clinical clues to the cause of bronchiectasis, the following investigations are useful in determining a cause:
- full blood count and differential white cell count
- serum total IgE, specific IgG and IgE to Aspergillus (with or without Aspergillus skin-prick testing)
- serum IgG, IgM and IgA
- sputum culture and susceptibility testing (including testing for mycobacteria)
- cystic fibrosis (CF) sweat chloride test in children, and in adults with symptoms of CF (see Cystic fibrosis)
- screening for autoimmune disorders, if appropriate (eg rheumatoid factor [RF], antinuclear antibodies [ANA]).
Specific testing for primary ciliary dyskinesia (PCD), alpha-1 antitrypsin deficiency and complex immunodeficiencies may be ordered by specialists.
Severity, morbidity and mortality of bronchiectasis can be estimated using the FACED score, or the Bronchiectasis Severity Index (BSI), which also estimates hospitalisation admissions, exacerbations and quality of life.