Coffee-bean sign (sigmoid colon)

Dr Dan J Bell and A.Prof Frank Gaillard et al.

The coffee-bean sign (also known as the kidney bean sign or bent inner tube sign 4) is a sign on an abdominal plain radiograph of a sigmoid volvulus although some authors have also used the term to refer to closed loop small bowel obstructions. Caecal volvulus may be mistaken with sigmoid volvulus and the number of air-fluid levels help in differentiating the two entities. In caecal volvulus only one air-fluid level is seen compared to sigmoid volvulus with a few air-fluid levels 4

This thick 'inner wall' represents the double wall thickness of apposed loops of bowel, with thinner outer walls due to single wall thickness.

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Article information

rID: 1145
Section: Signs
Synonyms or Alternate Spellings:
  • Coffee bean sign
  • Bent inner tube sign

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Cases and figures

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    Figure 1: coffee bean
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    Coffee bean sign.
    Case 1: with perforation
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    Case 2
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    Case 3
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    Case 5: on virtual colonoscopy
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