# Sentinel loop

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Not to be confused with [Sentinel value loop](/source/Sentinel_value_loop).

A **sentinel loop** is a [sign](/source/Radiologic_sign) seen on a radiograph that indicates localized [ileus](/source/Ileus) from nearby inflammation.[1] Simply put, it is the dilation of a segment of [small intestine](/source/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. This loop is called a "sentinel loop." It arises from the body's efforts to localize traumatic or inflammatory lesions. The local distention of that intestinal loop is due to local paralysis and accumulation of gas in the intestinal loop. In acute [pancreatitis](/source/Pancreatitis), the sentinel loop is usually seen in the left [hypochondrium](/source/Hypochondrium), while in acute [cholecystitis](/source/Cholecystitis), it is seen in the right hypochondrium. In acute [appendicitis](/source/Appendicitis), the sentinel loop is seen in the [right lower quadrant](/source/Quadrants_and_regions_of_abdomen#Quadrants).[2]

## References

1. Brant, William E. & Helms, Clyde A. (2007). [*Fundamentals of Diagnostic Radiology*](https://books.google.com/books?id=Sossht2t5XwC&dq=Sentinel+loop&pg=PA742). Lippincott Williams & Wilkins. p. 742. ISBN 9780781761352. Retrieved 18 September 2019.

1. Levitin, Joseph (1946). "Scout Film of the Abdomen". *Radiology*. **47** (1): 10–29. Radiological Society of North America (RSNA). [doi:10.1148/47.1.10](https://doi.org/10.1148/47.1.10). [ISSN 0033-8419](https://www.worldcat.org/issn/0033-8419). [PMID 20992153](https://pubmed.ncbi.nlm.nih.gov/20992153)

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Adapted from the Wikipedia article [Sentinel loop](https://en.wikipedia.org/wiki/Sentinel_loop) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Sentinel_loop?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.