Shifting pleural effusions.
The patient's position in bed may cause repositioning of free pleural fluid, which can track to paravertebral, subpulmonary, and paramediastinal planes. Awareness of this situation aids the clinician's recognition of the nature of the lesion on chest roentgenograms.
D006801:Humans; D010996:Pleural Effusion / Q000000981:diagnostic imaging*; D011187:Posture; D011859:Radiography