Air bronchogram (summary)

Dr Jeremy Jones et al.

Air bronchogram describes gas within a bronchus that is surrounded by alveoli filled with fluid, pus or other material. It is a very useful sign because it is highly sensitive and specific for the presence of consolidation rather than collapse.

Reference article

This is a summary article; read more in our article on air bronchogram.

  • pathophysiology
    • gas-filled bronchus inside consolidated lung
      • pus/fluid/cells within the alveolar spaces
    • proves pulmonary consolidation
      • useful when differentiating from collapse
  • investigation
    • chest x-ray
      • first line investigation for chest pathology
      • air-bronchogram helps to differentiate airspace opacification from collapse
    • CT chest
      • only used if there is suspicion of underlying complications
        • e.g. cancer, lung abscess
Plain radiograph

On a plain radiograph, gas is black. Soft-tissue is denser and therefore, closer to white. So, an air-bronchogram appears as a black, gas-filled bronchus within an area of white, airspace opacification.

If there are air bronchograms in a region of density it must be airspace opacification and not atelectasis (collapse) or pleural fluid.


The appearances on a CT mirror those of a chest radiograph. The difference is that rather than 1 image of the lungs, you have slices through the lungs every 1-5 mm (depending on how the CT is performed).

Medical student radiology curriculum
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Article Information

rID: 51427
System: Chest
Synonyms or Alternate Spellings:

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Cases and Figures

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    Case 1: left lower lobe pneumonia
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    Case 2: right upper lobe consolidation
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    Case 3: air bronchograms on CT
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