Coffee bean sign

The sigmoid colon is a part of the large intestine; it can twist upon itself abnormally – sigmoid volvulus.

Sigmoid volvulus is a life threatening condition that can present with vomiting, abdominal distension, abdominal pain and inability to pass flatus and stool, which emanate from intestinal obstruction caused by the sigmoid colon twisting on itself.

Abdominal X-rays in individuals with sigmoid volvulus usually have the coffee bean sign, so named because the dilated obstructed bowel which has coiled upon itself has an appearance resembling a coffee bean.

The coffee bean sign is also known as the 'omega', 'bent inner tube' or 'inverted U’ sign. The coffee bean sign is not exclusive to sigmoid volvulus, it can also be a feature of other diseases.

Reference:

Feldman D. The coffee bean sign. Radiology, 2000 216:178-179 (also source of image). Go to reference

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Abdominal X-ray showing the coffee bean sign, coffee beans 

Image reproduced with the kind permission of the Radiological Society of North America (RSNA®) - click here for image caption 

Image from Wikimedia Commons