Rigler's sign

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Rigler's sign

  • If there is free intra-abdominal gas adjacent to a gas-filled loop of bowel then both sides of the bowel wall are well-defined. This is known as 'Rigler's sign'.

Rigler's sign

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Rigler's sign

  • The multiple loops of dilated gas-filled bowel indicate small bowel obstruction.
  • Rigler's sign is visible, and so obstruction has been complicated by perforation.
  • When gas surrounds multiple loops of bowel there may be formation of sharp points or triangles (arrowheads).

Rigler's sign

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Rigler's sign

  • Rigler's sign is often less obvious.
  • This image shows a tiny triangle of gas outside the bowel, indicating pneumoperitoneum. Even this tiny volume of free gas is potentially life-threatening in the context of suspected perforation.
  • If in doubt make sure there is a good quality ERECT chest X-ray available.

Rigler's sign - Chest X-ray

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Rigler's sign - Chest X-ray

  • If perforation is suspected an erect chest X-ray is more sensitive than an abdominal X-ray for detection of free gas.
  • Occasionally Rigler's sign is visible on the erect chest X-ray. This image shows free gas under the diaphragm which outlines the outer side of the bowel wall.