Table 3.

Selected lung ultrasound (LUS) signs and phenomena

Sign/phenomenon	Description
Lung sliding	Presence of perceptible motion at the level of pleural line
Seashore sign	Physiologic, seen in the case of aerated lung On M-mode image one can distinguish sea above the level of pleural line (resulting from lack of movement) and sand below it (Merlin’s space dynamics)
Stratosphere/barcode sign	Pathologically seen in case of pneumothorax On image one can see only parallel horizontal lines, resembling barcode
Lung point	Point at which pneumothorax (lack of lung sliding) meets with normal lung sliding (or pathologic artifacts)
Double lung point	Presence of dense ground glass rockets in lower lung fields and relative aeration of upper lung fields, with sharp demarcation between 2
Lung pulse	Absence of lung sliding in conjunction with pulsing motion synchronous to heart activity
Static air bronchogram	Seen as hyperechoic branching structures in consolidations
Dynamic air bronchogram	As above, with real-time movement seen during ventilation (centrifugal on inspiration, centripetal on expiration)
Fluid bronchogram	Usually anechoic branching structures with hyperechoic wall
Lung hepatization	Tissue-like appearance of lung consolidation, similar in echotexture to liver
Shred/fractal sign	Seen in consolidations, name comes from shredded border between consolidated and normal lung
Suspended microbubble sign	Air bubbles suspended in viscous, dense pleural effusion
Plankton sign	Presence of tiny hyperechoic spots swirling in pleural fluid with respiratory and occasionally cardiac motion
Jellyfish sign	Lung rocking in pleural effusion – resembles jellyfish
Sinusoid sign	M-mode equivalent of jellyfish sign, resembles sinusoid