11/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation

Abdominal X-ray (AXR) interpretation

Table of contents

Introduction

This guide provides a structured approach to abdominal X-ray interpretation and includes examples of relevant pathology.

Con

Begin abdominal X-ray interpretation by checking the following details\:
Patient details\: name, date of birth and unique identi
Date and time the
Previous imaging\: useful for comparison.

Assess image type and quality

Projection of image

Assess the projection of the abdominal X-ray.
Typical projections of an abdominal X-ray include\:
Anterior-posterior (AP) supine
Anterior-posterior (AP) erect

Exposure of image

Assess the X-ray to ensure the whole abdomen is visible from the level of the diaphragm to the pelvis.
Ensure the exposure is adequate to allow radiological assessment of both the small and large bowel.
Abdominal X-rays do not provide a good view of posterior abdominal structures due to overlying bowel and gas.
If bowel perforation is being considered, you don't usually require an abdominal
this allows free gas under the diaphragm to be identi
to the X-ray to allow time for the air to rise).

A structured approach to interpretation

It's important to have a systematic approach to interpreting abdominal X-rays as this decreases the risk of missing pathology.
In this guide we use the BBC approach\:
Bowel and other organs\: small bowel, large bowel, lungs, liver, gallbladder, stomach, psoas muscles, kidneys, spleen and
bladder.
Bones\: ribs, lumbar vertebrae, sacrum, coccyx, pelvis and proximal femurs.
Calci

Bowel and other organs

https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 1/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation

Small and large bowel

Di
number of clues that may help you\:
The small bowel usually lies more centrally, with the large bowel framing it.
The small bowel’s mucosal folds are known as valvulae conniventes and are visible across the full width of the bowel.
The large bowel wall features pouches or sacculations that protrude into the lumen, known as haustra. In between the
haustra are spaces known as plicae semilunaris. The haustra are thicker than the valvulae conniventes of the small bowel
and typically do not appear to completely traverse the bowel. This distinction is unfortunately unreliable as dilated large
bowel can have a haustral pattern that does, in fact, traverse the bowel.
Faeces have a mottled appearance and are most often visible in the colon, due to trapped gas within solid faeces.
Bowel diameter
The upper limits for the normal diameter of di
Small bowel\: 3cm
Colon\: 6 cm
Caecum\: 9 cm
This is often referred to as the ‘3/6/9 rule’
.
A normal abdominal X-ray showing large bowel (white arrow) framing the small bowel (black arrow) [5]
Small bowel obstruction
Typical abdominal X-ray features of small bowel obstruction include dilation of the small bowel (>3cm diameter) and much
more prominent valvulae conniventes creating a 'coiled-spring appearance'
.
Adhesions are the most common cause of small bowel obstruction in the developed world accounting for 75% of all cases.
Some other causes include abdominal hernias (10%) and either intrinsic or extrinsic compression by neoplastic masses.
9
When interpreting an abdominal X-ray you should always inspect the inguinal regions, particularly if considering a hernia as a
cause of small bowel obstruction, as they are often fairly obvious (even on plain abdominal X-rays).
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 2/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation
Small bowel obstruction (note the dilated loops of small bowel creating a “coiled-spring” appearance)
Large bowel obstruction
The most common causes of large bowel obstruction include colorectal carcinoma and diverticular strictures. Less
common causes include hernias and volvulus.
Volvulus involves a twisting of the bowel on its mesentery and most commonly occurs at the sigmoid colon or caecum.
Patients with volvulus are at high risk of bowel perforation and/or bowel ischaemia secondary to vascular compromise.
Typical abdominal X-ray
Sigmoid volvulus\: a characteristic ‘co
Caecal volvulus\: often described as having a fetal appearance.
Large bowel obstruction [1]
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 3/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation
Rigler’s (double wall) sign
In healthy individuals, only the inner wall of the bowel should be visible on an abdominal X-ray. The presence of free air within
the abdomen (pneumoperitoneum) can result in both sides of the bowel wall becoming visible (this is known as Rigler's sign).
Causes of pneumoperitoneum include a perforated abdominal viscus (e.g. perforated bowel, perforated duodenal ulcer) and
recent abdominal surgery.
You should look closely for free air under the diaphragm on an erect chest X-ray if you suspect pneumoperitoneum.
Rigler's sign [2]
In
Features of in
Thumbprinting\: mucosal thickening of the haustra due to in
thumbprints projecting into the lumen.
Lead-pipe (featureless) colon\: loss of normal haustral markings secondary to chronic colitis.
Toxic megacolon\: colonic dilatation without obstruction associated with colitis.
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 4/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation
Toxic megacolon in a patient with ulcerative colitis. Note the lead-pipe colon with loss of the normal haustral folds due to chronic colitis. [6]

Other organs and structures

Although abdominal X-ray isn't an ideal imaging modality for assessing the structures listed below, it's useful to be able to
recognise them to help orientate yourself and identify relevant pathology\:
Lungs\: inspect the lung bases for pathology (e.g. consolidation) as abdominal pain can, in some cases, be caused by basal
pneumonia.
Liver\: a large right upper quadrant structure.
Gallbladder\: rarely visible on an abdominal X-ray, however, you should quickly inspect for calci
cholecystectomy clips.
Stomach\: visible between the left upper quadrant and midline, containing a variable amount of air.
Psoas muscles\: the lateral edge is marked by a relatively straight line either side of the lumbar vertebrae and sacrum.
Kidneys\: both are often visible, the right kidney is lower than the left due to the presence of the liver on the right.
Spleen\: located in the left upper quadrant, superior to the left kidney.
Bladder\: has a variable appearance depending on the fullness of the bladder.
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 5/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation
Other structures visible on an abdominal X-ray

Bones

Lots of bones are visible on an abdominal X-ray and it's important that you can identify each and screen for pathology. In
addition, bones on an abdominal X-ray provide useful landmarks which allow you to approximate the location of soft tissue
structures (e.g. the ischial spines are the usual level of the vesicoureteric junction).
Bony structures commonly visible on abdominal X-ray include\:
Ribs
Lumbar vertebrae
Sacrum
Coccyx
Pelvis
Proximal femurs
A wide range of bony pathologies can be identi
bony metastases.
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 6/711/13/24, 7\:30 PM Guide | Abdominal X-ray (AXR) interpretation
Sclerotic bony metastases (arrows) in a male patient with prostate cancer [3]

Calci

Various high density (white) areas of calci
Calci
Renal stones/staghorn calculi
Pancreatic calci
Vascular calci
Costochondral calci
Contrast (e g following a barium meal)
Source\: geekymedics.com
https\://app.geekymedics.com/osce-guides/data-interpretation/abdominal-x-ray-AXR-interpretation/ 7/7