Colon Cutoff Sign

Fig. 1: Supine abdominal radiograph in a 30-year-old man with acute abdominal pain shows gas in the transverse colon (C) with an abrupt termination at the level of splenic flexure (arrowheads). The more distal colon is decompressed. S = stomach
Fig. 2: Axial CT image of the same patient (done a few hrs later) shows extensive inflammation and necrosis of the pancreas (arrows) with free fluid in the abdomen (stars).

What is Colon Cutoff Sign?
Abrupt termination of gas in proximal colon at the level of the splenic flexure.
Applied to radiography, CT and contrast enema studies

What Can Cause Colon Cutoff Sign?

• Most common = acute pancreatitis
• True colonic obstruction e.g. colonic malignancy
• Other causes of colonic inflammation

Why Does It Occur?
In acute pancreatitis, inflammatory exudates in retroperitoneal space extend into 'phrenicocolic ligament' causing spasm of the splenic flexure wherer the colon returns to retroperitoneum. (Remember - transverse colon in peritoneal cavity, descending colon in retroperitoneum, phrenicocolic ligament is a transition point where transverse and descendinc colon is separated)

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Reference:
Pickhardt P. The colon cutoff sign. Radiology 2000;215:387.