Atelectasis (summary)

Atelectasis describes loss of lung volume secondary to collapse. It has many causes, the root of which is bronchial obstruction with absorption of distal gas. Atelectasis may be subsegmental, segmental, lobar, or involve and entire lung. 

Reference article

This is a summary article; read more in our article on lobar collapse.


  • pathophysiology
    • bronchial obstruction
      • inflammation, infection, cancer, foreign body
    • distal gaseous absorption
    • partial or complete loss of volume distal to the obstruction
    • lung parenchyma collapses down
    • associated volume loss
  • Drowned lung: occasionally the obstructed portion of the lung is filled with fluid and exudate resulting in minimum volume loss. This condition results in a specific imaging appearance which is called " drowned lung"


  • radiographic features
    • chest x-ray
      • increased density and reduced volume
      • useful to determine the cause, e.g. lung cancer
      • assess for complications
    • CT chest
      • more accurately depicts the involved segment
      • helpful in determining the cause, e.g. cancer
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Article information

rID: 51373
System: Chest
Synonyms or Alternate Spellings:

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Cases and figures

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    Case 1: right upper lobe collapse in cancer
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    Case 2: left lower lobe collapse
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    Case 3: right middle lobe collapse on CT
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