Pneumoperitoneum – AXR

45 Pneumoperitoneum – AXR

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Fig. 45.1A Large pneumoperitoneum.

Background

Please see Chapter 27 for an account of perforation on an erect CXR.

The diagnosis of pneumoperitoneum is more difficult to make on an AXR than a CXR. However, if it is suspected, both an erect CXR and supine AXR should be performed as an erect CXR is only 80% sensitive for perforation and an AXR may provide further information. AXR is, however, only about 50% sensitive for perforation.

The AXR may also reveal the cause of the perforation, for example obstruction.

Clinical features

Please see Chapter 27.

Radiological features

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Fig. 45.1B Rigler’s sign: On a normal AXR, all air is contained within the bowel lumen. Thus it only outlines the luminal surface of the bowel (arrow 1), The luminal surface of the bowel can be seen because of the difference in density between air and bowel wall (see Introductory section, p. 3).

When a viscus perforates, there is air within the peritoneal cavity which can now outline the outside of the bowel wall (arrow 2). This is known as Rigler’s sign, where both sides of the bowel wall are seen.

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Aug 20, 2016 | Posted by in ULTRASONOGRAPHY | Comments Off on Pneumoperitoneum – AXR

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