Ans- A Ref- Mnemonics CRAWLS 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 pectoralis major L: lungs, e.g. airway obstruction, emphysema, Swyer-James syndrome, unilateral large bullae, large pulmonary embolus S: scoliosis 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 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 opposite lung in a recumbent patient S: Swyer-James syndrome (Macleod syndrome). References