Sigmoid volvulus. This is a fairly straightforward radiographic diagnosis – the sigmoid colon twists on its mesentery and becomes massively dilated, extending out of the pelvis and left iliac fossa, and often reaching the right upper quadrant. This example has the classic ‘coffee-bean’ appearance – the margins of the coffee bean are outlined by the yellow arrows while the white arrows indicate the line which is supposed to resemble the groove in the middle of a coffee bean. Sigmoid volvulus is a form of ‘closed-loop’ obstruction – by twisting on its mesentery, the lumen of the sigmoid becomes obstructed at both ends. This puts it at high risk of ischaemia and perforation.