Sentinel loop

Sentinel loop sign is a short segment of paralytic ileus or adynamic ileus close to an intra-abdominal inflammatory process ¹. The sentinel loop sign may aid in localizing the source of inflammation. For example, a sentinel loop in the upper abdomen may indicate acute pancreatitis, while one in the right lower quadrant may be due to acute appendicitis.

Figure 1. Sentinel loop

Footnote: Focal area of adynamic ileus close to the appendix location at right lower quadrant in a patient with abdominal pain and tenderness is compatible with a sentinel loop due to acute appendicitis.

References

1. Nontraumatic Emergent Abdominal Vascular Conditions: Advantages of Multi–Detector Row CT and Three-Dimensional Imaging. Thomas Frauenfelder, Simon Wildermuth, Borut Marincek, and Thomas Boehm. RadioGraphics 2004 24:2, 481-496 https://doi.org/10.1148/rg.242025714