Mnemonic for Unilateral Hyperlucent Hemithorax

Three useful Mnemonics to help you remember the causes for a unilateral hyperlucent hemithorax are



  • C: contralateral lung increased density, e.g. supine pleural effusion
  • R: rotation
  • A: air, e.g. pneumothorax
  • W: wall, e.g. chest wall mass, mastectomy, polio, Poland syndrome, surgical removal of the pectoralis major muscle
  • L: lungs, e.g. airway obstruction, emphysema, Swyer-James syndrome, unilateral large bullae, large pulmonary embolus
  • S: scoliosis

Another useful mnemonic for causes of hyperlucent hemithorax is SAFE POEM.
  • S: Swyer-James syndrome
  • A: agenesis (pulmonary)
  • F: fibrosis (mediastinal)
  • E: effusion (pleural effusion on the contralateral side) 
  • P: pneumonectomy/pneumothorax 
  • O: obstruction 
  • E: embolus (pulmonary)
  • M: mucous plug

A third commonly used mnemonic for hyperlucent hemithorax is ACROSSS.

  • A: air- pneumothorax

          artery – pulmonary aplasia or hypoplasia

  • C:  chest wall – mastectomy, polio, Poland syndrome
  • R:  rotated film
  • O: obstructive causes – airway obstruction, foreign body, unilateral emphysema, or large embolus
  • S: scoliosis
  • S: surrounding – increased density in contralateral lung, e.g. pleural effusion in the opposite lung in a recumbent patient
  • S:  Swyer-James syndrome (Macleod syndrome).

More useful mnemonics below

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