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Imaging of pneumothorax

Paul Stark, MD
Section Editors
Nestor L Muller, MD, PhD
V Courtney Broaddus, MD
Deputy Editors
Geraldine Finlay, MD
Susanna I Lee, MD, PhD


Pneumothorax refers to gas within the pleural space [1-4]. Its clinical manifestations are widely variable. Small pneumothoraces can be asymptomatic and self-limited, but need to be monitored for progression. Large pneumothoraces can cause hypoventilation, hypoxemia, and/or hemodynamic instability. If such pneumothoraces are not promptly treated, progression to cardiac arrest and death is possible.

Radiographic imaging of a pneumothorax is reviewed here. The causes and management of a pneumothorax are discussed separately. (See "Primary spontaneous pneumothorax in adults" and "Secondary spontaneous pneumothorax in adults".)


The first-line imaging modalities used to identify a pneumothorax are chest radiography and computed tomography (CT). Ultrasound can also be used to image pneumothorax, especially in the emergency situation. We would endorse confirming the ultrasound diagnosis of pneumothorax with conventional radiographs or CT scanning prior to interventional procedures if time and circumstances allow.

Chest radiographs — The main feature of a pneumothorax on a chest radiograph is a white visceral pleural line, edge or interface, which is separated from the parietal pleura by a collection of gas (image 1). In most cases, no pulmonary vessels are visible beyond the visceral pleural line (the collection of pleural gas is avascular). A pneumothorax may be identified on an upright, supine, or lateral decubitus chest radiograph. The lateral decubitus view tends to be the most sensitive, while the supine view is the least sensitive.

Upright – In an upright patient with a pneumothorax, most pleural gas accumulates in an apicolateral location (image 2 and image 3). The visceral pleural line appears either straight or convex towards the chest wall. As little as 50 mL of pleural gas may be visible on a chest radiograph [5]. Although a pneumothorax is generally accompanied by a considerable loss of lung volume, the collapsed lung preserves its transradiancy because hypoxic vasoconstriction diminishes the blood flow to the collapsed lung [6].

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Literature review current through: Nov 2017. | This topic last updated: Mar 01, 2017.
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