Published in:
01-10-2015 | Classics in Abdominal Imaging
Coffee bean sign
Published in: Abdominal Radiology | Issue 7/2015
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The coffee bean sign is a metaphor describing the classic radiographic appearance of a closed loop obstruction, most notably associated with sigmoid volvulus [1, 2]. Twisting of the sigmoid colon about its mesenteric axis creates an inverted, U-shaped, and a gas-filled segment of dilated bowel originating in the pelvis and extending cephalad. A central linear opacity bisects the dilated loop (Fig. 1a), mimicking the cleft of a coffee bean (Fig. 1b). This central line represents the “double” thickness of apposed bowel walls [3] (Fig. 2).
Fig. 1
A Sigmoid volvulus. Supine frontal radiograph showing the inverted U-shaped sigmoid colon which resembles a coffee bean. The thick inner wall (“cleft”) represents the “double” thickness of apposed bowel walls (red arrows). B Photograph of a roasted coffee bean. Note the central cleft (red arrow).
Fig. 2
Sigmoid volvulus. CT scout view reveals the typical inverted U-shaped sigmoid colon with the coffee bean configuration (red arrows). Note the dilation of the more proximal colon, and extension of the distended sigmoid loop cephalad to the transverse colon (northern exposure sign) [5].
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