Radiological Anatomy: Large Intestine


This page is dedicated to covering how the large intestine will appear across different radiological studies.


An abdominal X-ray is a very routinely ordered study, and a core component of reading this study is to evaluate the appearance of the large intestine.

Appearance of large bowel on a KUB. Note the haustra (folds of the bowel) that do NOT span the entire lumen (source)
Appearance of large bowel on a KUB (white arrows) contrasted with small bowel (black arrow). Note the haustra (folds of the bowel) that do NOT span the entire lumen (source)

Characteristics of the large bowel on a KUB: the below features can help identify the large bowel on a KUB.

  • Circumferential location: given the anatomical location of the large intestine it often will be found on the borders of the abdomen.
  • Gas pattern: there will be varying amounts of gas in the large bowel, but there will almost always be air in the rectum and sigmoid colon.
  • Air/fluid levels: very little to none present in normal large bowels.
  • Diameter: when dilated the large bowel can become very large.
  • Haustra: these intestinal markings will be visible, however they will not go across the entire length of the bowel lumen.
  • Stool: the nature of the large intestine justifies the fact that stool may be present in this structure.


Page Updated: 10.07.2016