Colon cut-off sign | Radiology Signs

The colon cut-off sign is caused by localized inflammation or irritation of the splenic flexure of the colon, most commonly due to acute pancreatitis. This inflammatory process involves the pancreas and extends to adjacent colonic structures, leading to a marked dilatation of the proximal transverse colon with an abrupt transition to the collapsed distal colon at the splenic flexure. Other conditions such as splenic infarction, colonic ischemia, trauma, gastric cancer, splenic artery bleeding, and ruptured abdominal aortic aneurysm can also produce this sign by similar localized inflammatory mechanisms or ischemic changes.

Why is it called so?

It is named the “colon cut-off sign” because it radiographically appears as an abrupt termination or “cut-off” of gas within the colon at the splenic flexure, where dilated proximal colon sharply transitions to a collapsed distal segment on abdominal radiographs or computed tomography (CT). The visual impression is that the colon is “cut off” at this anatomical point.

Pathophysiology

Inflammatory mediators and pancreatic enzymes leak from an inflamed pancreas through the phrenicocolic ligament and associated ligaments to the splenic flexure area, causing localized colonic spasm and paralytic ileus. This results in gaseous distension of the proximal colon but decompression beyond the splenic flexure. Continued inflammation can lead to colonic ischemia and edema, further impairing distal gas passage and sometimes risking colonic perforation. The sign thus reflects the spread of peripancreatic inflammation to the adjacent colon producing a localized functional obstruction at the splenic flexure.