Sinusoid sign (ultrasound)

Dr Francis Fortin and Dr Tim Luijkx et al.

The sinusoid sign is a dynamic sonographic sign, present when respiratory variation decreases the distance between the parietal and visceral pleura, when separated by a pleural effusion. Classically demonstrated in M-mode, the appearance of which the moniker is derived, it is specific for the identification of a pleural effusion, although insensitive, as it may be absent with dense or heavily septated collections.

A subtype of the sinusoid sign is the "jellyfish sign," which alludes to the supposed appearance of this respiratory dynamic on B-mode.

The dynamic counterpart to the quad sign, it demonstrates the fluid dynamic of the collection observed, thus distinguishing a pleural effusion from other lung pathology, such as consolidation, or a hiatal hernia, both of which may appear anechoic and mimic the sonomorphology of a pleural effusion.

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Article information

rID: 30810
System: Chest
Section: Signs
Synonyms or Alternate Spellings:

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Cases and figures

  • Anechoic pleural effusion (ultrasound)
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