Which ultrasound findings suggest pneumothorax?

Updated: Apr 28, 2020
  • Author: Brian J Daley, MD, MBA, FACS, FCCP, CNSC; Chief Editor: Mary C Mancini, MD, PhD, MMM  more...
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Features of the ultrasonographic examination for the diagnosis of pneumothorax include absence of lung sliding (high sensitivity and specificity), absence of comet-tail artifact (high sensitivity, lower specificity), and presence of lung point (high specificity, lower sensitivity).

In the absence of pleural disease, visceral pleura move against parietal pleura while breathing. This movement of the 2 pleura is detected by the ultrasound as lung sliding, which is a "kind of twinkling synchronized with respiration" seen in real-time and time-motion modes. That is, lung sliding refers to normal pleural movement in patients without pneumothorax. [50] One study showed absent lung sliding from an anterior approach indicated pneumothorax with 81% sensitivity and 100% specificity.

Comet-tail artifacts are vertical air artifacts that arise from the visceral pleural line (or in the case of parietal emphysema or shotgun pellets may arise above the pleural line). Lung point is the location that lung-sliding and absent lung-sliding alternately appear; it has been shown in multiple studies to allow determination of the size of a pneumothorax. Zhang et al obtained a 79% sensitivity in lung point's ability to determine pneumothorax size. [51]

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