Colon Cutoff Sign

The colon cutoff sign describes the abrupt termination of gas within the proximal colon at the level of the radiographic splenic flexure, usually with decompression of the distal colon.

Inflammatory exudate in acute pancreatitis that extends into the phrenicocolic ligament by directly spreading through the lateral attachment of the transverse mesocolon gives rise to this sign.

Infiltration of the phrenicocolic ligament results in functional spasm and/or mechanical narrowing of the splenic flexure at the level where the colon returns to the retroperitoneum.

This transition point, or cutoff, is further accentuated by distention of the intraperitoneal transverse colon from the focal adynamic ileus, which is also a result of the underlying inflammatory process. This appearance can mimic a true colonic obstruction.