A sentinel loop is a sign seen on a radiograph that indicates localized ileus from nearby inflammation.
[1] Simply put, it is the dilation of a segment of small intestine to be differentiated from colonic cutoff sign which is a dilation of a segment of large bowel.
[citation needed] An isolated distended loop of bowel is seen near the site of injured viscus or inflamed organ.
It arises from the body's efforts to localize traumatic or inflammatory lesions.
In acute appendicitis, the sentinel loop is seen in the right lower quadrant.