Investigations

A panel of investigations should be performed to establish the underlying cause of bronchiectasis (1):

• full blood count - blood eosinophilia is common in allergic bronchopulmonary aspergillosis
• serum total IgE and assessment of sensitization (specific IgE or skin prick test) – to assess Aspergillus fumigatus
• serum immunoglobulin determination - should be done at presentation by measuring serum IgG, IgA and IgM levels and serum electrophoresis (1)
• consider measuring baseline specific antibody levels against capsular polysaccharides of Streptococcus pneumoniae in all patients to investigate for specific antibody deficiency
  • if antibodies are low, immunise with 23 valent polysaccharide pneumococcal vaccine followed by measurement of specific antibody levels 4-8 weeks later (1)
• sputum examination:
  • obtained by deep coughing, physiotherapy or aerosol inhalation (1)
  • with the naked-eye to confirm patients account
  • bacteriological examination
  • tests for mycobacteria are essential in all children and adults (1)
• chest radiography:
  • to exclude obvious localised lung disease
  • note that only about 50% of patients with bronchiectasis does a chest X-ray show the characteristic features of thickened bronchial walls (seen as parallel 'tramlines', ring or curvilinear opacities), cystic lesions with fluid levels, areas of collapse with crowding of pulmonary vasculature, or scarring (1)
• lung function tests to assess extent of lung damage
  • in children (usually >5 years) - FEV1, FVC, forced expiratory flow (FEF)
  • in adults - FEV1, FVC, peak expiratory flow PEF (1)
• screening for cystic fibrosis
  • done in all children and adults up to 40 years of age and adults over 40 years with clinical features suggestive of cystic fibrosis
  • two measurements of sweat chloride
  • CFTR genetic mutation analysis (1)
• high resolution CT scan:
  • is the investigation of choice to confirm the diagnosis (1)
  • used in patients in whom bronchiectasis is suspected but the X-ray is unhelpful
  • characteristic features seen in HRCT are
    • bronchial wall dilation (internal diameter of the lumen is bigger than the diameter of the accompanying bronchial artery)
    • lack of bronchial tapering (2)
• bronchoscopy is indicated to investigate haemoptysis or to exclude an obstructing lesion in localised bronchiectasis (1)
• gastrointestinal investigations such as 24-hour pH monitoring, barium studies
  • the threshold for gastrointestinal investigations should be low for children due to the higher incidence of structural abnormalities
  • gastric aspiration should also be considered as a cause after lung transplantation (1)
• urinalysis:
  • amyloidosis may cause proteinuria.

Reference:

1. Hill AT, Sullivan AL, Chalmers JD, et al British Thoracic Society guideline for bronchiectasis in adults. BMJ Open Respiratory Research 2018;5:e000348. doi: 10.1136/bmjresp-2018-000348.