John Wiley & Sons, Ltd., The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, British Editors. The most new and exciting aspect of abdominal x-rays for medical students is the way it uses color overlays to emphasize anatomy and pathology. mark', the radiographs distinguish this book from others and make it easy to appreciate the sign or pathology of interest.
Structures can only be seen if there is sufficient contrast with surrounding tissues (contrast is the difference in absorption between one tissue and another)
Patient safety and the use of ionizing radiation for medical exposures is governed by specific legislation in the UK – the Ionizing Radiation (Medical Exposure) Regulations or IRMER. The patient is asked to hold their breath (so that breathing movements do not blur the image) and the X-ray is taken.
Right hypochondriac 2. Epigastric
Keep in mind that when looking at an abdominal x-ray, the left side of the image is the patient's right side, and the right side of the image is the patient's left side.
Left hypochondriac 4. Right lumbar
Liver (purple) 2. Spleen (pink)
Location of the pancreas (white outline) – not normally visualised
Right kidney (red) 2. Left kidney (red)
Location of right ureter (white outline) – not normally visualised
Location of left ureter (white outline) – not normally visualised
Urinary bladder (orange)
Gas in the rectum (green)
Location of right adrenal gland (white outline) – not normally visualised
Location of left adrenal gland (white outline) – not normally visualised
Location of the gallbladder (white outline) – not normally visualised
Left 12th rib (light green)
Psoas outline – left and right (red) 3. Vertebral body of L3 (light blue)
Right transverse processes of L1–L5 (black) 6. Spinous process of L4 (brown)
Sacrum (blue)
Coccyx (rose)
Right hemi‐pelvis (yellow) 10. Right sacroiliac joint (green)
Left femur (purple)
Ilium (green) 2. Pubis (red)
Obturator foramen (purple)
Location of right inguinal ligament (blue) – not normally visualised. The inguinal ligament runs
Shenton’s line (black outline) – imaginary line along the inferior border of the superior pubic
Right lung base (blue) – seen projected behind the liver
Left costophrenic angle (white outline)
Figure 14)
Stomach – note the stomach wall rugae (highlighted between the white arrows)
Ascending colon 4. Hepatic flexure
Transverse colon 6. Splenic flexure
Figure 15)
You should present an abdominal radiograph in a systematic way to ensure that you cover all areas and do not miss anything important. Look for clinically significant calcified structures such as calcified gallstones, kidney stones, nephrocalcinosis, pancreatic calcification, and an abdominal aortic aneurysm (AAA).
How to look?
What to look for in A – Air in the wrong place?
Look for a very large dilated bowel loop that may represent a sigmoid or cecal volvulus. Look at the left and right iliac regions for any intestinal gas seen projecting below the level of the inguinal ligament, suggesting an inguinal or femoral hernia.
What to look for in B – Bowel?
If a fracture is observed, use the 3 Polo ring test to look for a second fracture (or disruption of the pubic symphysis or sacroiliac joints). Look at the spine for loss of vertebral body height, loss of pedicle visualization, loss of normal alignment (eg, scoliosis), and bamboo spine (ankylosing spondylitis).
What to look for in D – Disability (bones and soft tissues)?
Bowel perforation
The key to identifying a pneumoretroperitoneum is to look for gas (black) surrounding all or part of the kidney. When gas is present in the retroperitoneal space, the edges of the kidneys are much easier to see.
Biliary‐enteric connection (abnormal connection between biliary tree and bowel)
It appears as branching dark lines in the center of the liver, usually larger and more prominent towards the hilum. Gas in the portal vein appears as dark branching lines within the periphery of the liver on a plain abdominal radiograph.
Ischaemic bowel (most common)
Necrotising enterocolitis (NEC) (most common in an infant)
Severe intra‐abdominal sepsis (diverticulitis/pelvic abscess/appendicitis)
In a normal individual, the small intestine is not visualized because it is collapsed or contains fluid. Dilation >3 cm: The small intestine is dilated if it is more than 3 cm in diameter. They are thin, closely spaced and classically seen as a continuous thin line across the entire width of the intestine.
The conditions in red are the four most important causes of small bowel obstruction to remember. You can tell it's the small intestine because it's in the middle and the valvulae conniventes can be seen everywhere. You can tell it's small intestine because the valvulae conniventes are visible everywhere.
You can tell it is the small intestine as it is in the center and the conniventes valves can be seen everywhere. Repeated episodes of cholecystitis cause the gallbladder to adhere to the intestine (usually the duodenum) and eventually a fistula forms.
Pneumobilia
Small bowel obstruction
Gallstone (usually in the right iliac fossa, but only seen in approximately 30% of cases)
The bowel proximal to the obstruction is dilated and the bowel distal to the obstruction is usually collapsed. Dilation >5.5 cm: The colon is dilated if it is more than 5.5 cm in diameter. The lines between the haustra are called haustral folds and usually do not cross the entire width of the intestine (unlike valvulae conniventes).
You can tell it's colon because it's distended >5.5 cm along the circumference and the haustra is visible inside. You can tell it's colon because it's distended >5.5cm (much larger than dilated small intestine would normally get) and the haustra is seen inside. The large intestinal loops are distended >5.5 cm, circumferentially located and a few haustra are seen inside.
The two loops of distended small intestine are identified by the presence of valvulae conniventes and indicate incompetence of the ileocecal valve as gas has passed retrograde from the large intestine to the small intestine. The right radiograph shows the dilated large intestine marked in green and the dilated small intestine marked in blue.
Bowel obstruction: The loop of twisted bowel causes a ‘closed‐loop’ obstruction
Bowel ischaemia: In some cases the twisting of the bowel mesentery compromises the vascular supply to the bowel leading to ischaemia and eventually necrosis, which can be fatal
Coffee bean sign: The shape of the distended gas filled ‘closed loop’ of colon looks like a large
General lack of haustra: Often the bowel is so
Distension of the ascending, transverse and descending colon: The colon proximal to the obstruction (volvulus) is often
Comma shaped: The shape of the distended gas filled ‘closed loop’ of colon often looks like a large comma (more rounded in
Haustra often visible: The haustral folds are often still clearly visualised, even when the bowel is very distended
Collapse of the ascending, transverse and descending colon: The colon distal to the obstruction (volvulus) is often
There is a circular comma-shaped loop of distended colon in the center of the abdomen, with visible haustra within it. There is a circular comma-shaped loop of distended colon in the center of the abdomen with some haustra visible within it. On the right side of the abdomen you can see that the duodenum is partially dilated as valvulae conniventes can be seen.
There is a loop of gas-filled intestine over the right inguinal region, below the right obturatory foramen and below the level of the inguinal ligament. The right x-ray shows the intestinal hernia in green and the position of the right inguinal ligament in gray. There is a loop of gas-filled intestine over the left inguinal area, over and below the left obturatory foramen and below the level of the inguinal ligament.
The right x-ray shows the intestinal hernia in green and the position of the left inguinal ligament in gray. There is a loop of gas-filled intestine over the left inguinal area, below the left obturatory foramen and below the level of the inguinal ligament.
Bowel wall thickening: Inflammation causes mucosal oedema and therefore thickening of the bowel wall. Often you can see the thickened bowel wall outlined by gas within the bowel lumen and peritoneal
Bowel inflammation can occur anywhere along the bowel, but is most commonly seen in the large intestine. Often you can see the thickened bowel wall surrounded by gas within the bowel lumen and peritoneal cavity.
Loss of formed faecal matter in the left‐hand side of the colon: Loss of the normal faecal matter in the left side of the colon indicates that the colon is not functioning properly and is suggestive of bowel
Diagrammatic representation of the appearances of ‘thumbprinting’
There is thickening of the intestinal wall with thickening of the haustral folds in the transverse colon. On the right X-ray, the inflamed intestine is highlighted in green and the thickening of the intestinal wall is highlighted in light green. There is a thickening of the intestinal wall and the colon appears featureless with loss of the normal intestinal wall due to chronic inflammation.
The right radiograph shows the inflamed bowel marked in green and the thickening of the bowel wall marked in light green. Bowel wall thickening is most easily seen in the transverse colon with severe thickening of the haustral folds giving a 'finger print' appearance. The rectum, sigmoid and descending colon are featureless with loss of normal haustra and have a 'lead pipe' appearance.
There is mild thickening of the bowel wall, and the descending colon is featureless with loss of the normal haustra giving it a 'lead pipe' appearance. The right radiograph shows the featureless bowel marked in green and the thickening of the bowel wall marked in light green.
Large bowel dilatation to >6 cm diameter
Inflammatory pseudopolyps (mucosal islands): Lobulated opacities in the bowel wall from areas of raised mucosal tissue surrounded by areas of ulceration
Thumbprinting and mucosal oedema may be present 4. Usually transverse colon affected (as in the following example)
Hardened faecal material inside the right side of the colon is very indicative of faecal loading as the faecal material here should normally be liquid. If gallstones are visible, they will be seen projected over the right upper quadrant along the lower border of the liver. Calcific density projected over the kidney: Look carefully over the area of the kidneys for any small calcific densities.
Look carefully in the course of the ureter for small calcifications, which can appear very subtle. Ureteral stones are seen along the line of the ureter (3), which runs along the line of the transverse processes (4). There are a few small calcified densities projected over the left kidney and a small calcified density projected over the lower pole of the right kidney consistent with kidney stones.
These are most likely consistent with ureteric stones as they protrude beyond the line of the right ureter and are too small to be calcified lymph nodes. The right x-ray shows the ureteric stones in yellow, the position of the right kidney in white, and the line of the right ureter marked by a white dashed line.
Urinary stasis (most common)
Migrated renal calculus 4. Foreign material left in place
There are several irregular foci of calcification projecting across the midline in the rough shape of the pancreas. The radiographic appearance is a triangular-shaped area of irregular calcification projected in the region of the upper pole of the kidney. On the right X-ray, the calcification of the adrenal gland is marked in yellow and the approximate position of the kidneys is marked with a white dashed line (not clearly visible).
An AAA will only be visualized on an abdominal radiograph if there is calcification in the wall of the aorta. Mural calcification appears as white lines projected across the lower abdomen, delineating the wall of the aorta. It occurs as fine or coarse calcification in the lower pelvis, just below the position of the urinary bladder.
There is an irregular calcification projecting over the lower pelvis just below the position of the bladder. Calcification of the wall of the aorta (and other major arteries) can occur in the elderly and in patients with diabetes.
Pelvic ring: The paired ilium, ischium and pubic bones along with the sacrum are held together by tough ligaments to form a large pelvic ring
If the pelvis is included on the X-ray, it is important to check for pelvic fractures. Pelvic ring: The paired ilium, ischial, and pubic bones, along with the sacrum, are held together by sturdy ligaments to form a large pelvic ring.
Ring of bone surrounding the right obturator foramen 3. Ring of bone surrounding the left obturator foramen
The right radiograph shows the approximate position of the hernia mesh repair, marked in orange. The right radiograph shows the NG tube marked in purple and the approximate position of the stomach marked in brown. The right radiograph shows the NJ tube marked in purple and the approximate position of the stomach marked in brown.
There is a metallic tubular stent designed on the right side of the abdomen in the position of the duodenum. There is a tubular metal stent designed on the left side of the abdomen in the region of the splenic flexure. There is an umbrella-like wire device projected just to the right of the midline at the line of the IVC.
The right x-ray shows the position of the IVC (usually not visible) highlighted in blue with a white outline. There is also a well-defined calcified opacity with a polygonal shape projecting over the right upper quadrant in the gallbladder region (marked in yellow). C: “Several small calcific densities (indicated in yellow) are projected on the left side of the lumbar spine.
Rugae (of the stomach) - The large ridges or folds seen in the lining of the stomach.
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