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Abdominal X-Ray Radiograph Interpretation

Abdominal X-Ray Radiograph Interpretation

AB'C' of Abdominal X-Ray


Some say that the abdominal X-ray is a bit harder to interpret than the CXR but I think the logic stays the same. As long as you have a system of looking at it, you should not miss the crucial bits and should stick in your mind.


Here is my take on it.

Start general then go to the specifics.


1. First, comment on the demographics (follow the arrows on the image below)

I follow my order of: This is an abdominal radiograph (don't say X-ray) of Mr X, in supine AP position, taken on 01/01/11. (unlike CXR which tends to be taken in erect PA, AXR tends to be supine AP)


2. Next, comment on PFR 

  • Penetration/exposure: Under exposure = Too black! Good? (Just about it... should be just be able to work out the spinous process) Over exposure = Too white.
  • Field: Diaphragm (you don't want to miss pneumo-peritoneum!) down to the groin (don't miss a hernia!) 
  • Rotation

3. The most obvious abnormality is...



4. Going through it systematically


A: Air (black)

  • Intraluminal: Small bowel (should not contain any air), large bowel (3-6-9 rule: Normal measurements – smal bowel <3cm, large bowel <6cm, caecum <9cm)         
    • Small bowel: Valvulae conniventes (continuous along bowel diameter), central location
    • Large bowel: Haustrae (non-continuous: 1/3 of bowel diameter only), peripheral location
  • Intramural: ischaemic colitis
  • Extraluminal: Biliary tree (gallstone ileus), diaphragm (in erect view: perforated viscus – pneumoperitoneum; though may be normal if abdominal surgery)


B: Bones and calcification (white)

  • Normal calcification: Spine, aorta
  • Abnormal calcification: Gallstone, pancreas, urinary tract stone


C: 'S'oft tissue (grey)

  • Spleen
  • Psoas shadow: Absence indicates any intra-abdominal or retroperitoneal fluid i.e. ruptured AAA or ascites


5. Summarise

  • In summary, This is an abdominal radiograph of Mr X, in supine AP position, taken on 01/01/01. There are signs of _______, in line with the diagnosis of ______.


    Familiarise yourself with the most commonly tested AXRs. Here are their signs. See corresponding AXRs in the images below arranged in descending order.

  • Pneumoperitoneum: Subphrenic air (solid white), Superior falciform-ligament sign (Dashed white), Inferior ligamentum-teres sign (solid black), Rigler's sign (dashed black)
  • Small bowel obstruction: Distended small bowel loops (valvulae conniventes - white arrow)
  • Large bowel obstruction: Distended large bowel loop
  • Sigmoid volvulus: Coffee bean sign in RLQ
  • Sentinel loop: Isolated ileus due to adjacent inflammation (RUQ: Cholecystitis, LUQ: Pancreatitis, LLQ: Diverticulitis, RLQ: Appendicitis)


Pneumoperitoneum. From [N Engl J Med, Lee CH, Radiologic Signs of Pneumoperitoneum, Vol 362, pg 2410Small Bowel Obstruction

Large Bowel ObstructionSigmoid Volvulus

Sentinel Loop secondary to Pancreatitis

Now have a go at commenting on this abdominal X-ray! (See below for my interpretation)



  1. Demographics... This is an abdominal radiograph of Mr Bean, taken in erect position, on 01/01/01.
  2. PFR... Penetration and field, is adequate. The patient does not appear to be rotated.
  3. Most obvious abnormality.. The most obvious abnormality is presence of multiple fluid-air levels and peripheral located bowel loop dilation, most likely the large bowel.
    1. A: Multiple air-fluid levels in peripheral location. There is no intramural air and no extraluminal air.
    2. B: No abnormal calcifications are visible.
    3. C: No soft tissue abnormalities are visible.
    1. Summarise: In summary, this is an abdominal radiograph of Mr Bean, in erect PA position, taken on 01/01/01. There are signs of bowel obstruction, with peripheral multiple air-fluid levels but no signs of a perforated viscus (Subphrenic air, Rigler's sign etc.); in line with a diagnosis of large bowel obstruction. 

    In summary:

    1. Demographics
    2. PFR
    3. Most obvious abnormality
    4. Systematic commentary on A, B, C
    5. Summarise


    My method may not suit all so it is best if you adapt it or find/create one that works for you! Good luck with your interpretation!



    • RadiologyMasterclass (2012). Abdomen X-ray. Available: Last Accessed Date:2012.
    • Images published with permission from (,
    • From [N Engl J Med, Lee CH, Radiologic Signs of Pneumoperitoneum, Vol 362, pg 2410 Copyright © (2013) Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.
    • Image courtesy of Dr Varun Babu, ( Creative Commons BY-SA-N



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