Abdominal x-ray review: bowel

Last revised by Dr Jeremy Jones on 14 Aug 2021

Abdominal x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using ABDO X is a helpful and systematic method for abdominal x-ray review, where B refers to the assessment of the bowel loops.


  • introduction
    • stomach, small bowel and large bowel may be differentiated on an abdominal x-ray
    • pathological features to detect include bowel dilatation, bowel loop displacement and bowel wall thickening
  • procedure
    • the stomach usually appears thick-walled and lies in the left upper quadrant, and may contain the tip of a nasogastric tube
    • can you identify the small and large bowel? Use these features:
      • the small bowel usually lies centrally, has folds than run all the way across the diameter of the lumen (valvulae conniventes) and usually contains a small volume of air
      • the large bowel lies peripherally, has folds that run part of the way across the diameter of the lumen (haustral folds) and usually contains some air and fecal matter
    • is the bowel dilated? 
      • the 3-6-9 rule refers to the approximate allowable diameter (in centimeters) of the small bowel, large bowel and cecum
    • are the bowel loops are clustered centrally with hazy homogeneous opacification of the rest of the abdomen?
      • this is an indication that there may be ascites
    • is the wall of the large bowel thickened and undulating in its contour?
      • this is known as thumbprinting and indicates colonic wall edema which may be due to infection, inflammation or ischemia

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Cases and figures

  • Case 1: small bowel obstruction
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