The sentinel loop sign

摘要

First reported by Levitan in 1946, the sentinel loop sign refers to the appearance of localized ileus on abdominal radiographs [1]. Levitan described a single distended loop of small bowel in cases of acute gallbladder disease, acute appendicitis, and subhepatic abscess on supine abdominal radiographs. This sign was subsequently used by Grollman et al. as a radiographic sign of pancreatitis in 1950 [2]. In the Oxford English dictionary, sentinel is defined as "a soldier or guard whose job is to stand and keep watch" [3] (Fig. 1). Medically, sentinel is defined as "an indicator of the presence of disease" [3]. As such, a dilated "sentinel loop" of bowel, or focal ileus, indicates the presence and likely location of adjacent pathology. For example, a sentinel loop in the upper mid-abdomen is classically used to diagnose acute pancreatitis (Fig. 2).