This document discusses the interpretation of abdominal x-rays. It provides information on common clinical indications for abdominal x-rays such as abdominal pain, distention, vomiting, and placement of lines or tubes. It also discusses the radiographic principles including the series of films taken and obtaining different views. Key things to look for on abdominal x-rays are described such as the bowel gas pattern, extraluminal air, soft tissue masses, and calcifications. Both normal findings and various abnormal findings are summarized, including signs of small bowel and large bowel obstruction, localized and generalized ileus, free air, and retroperitoneal air.

1. INTERPRETATION OF
ABDOMINAL X-RAY
GROUP DISCUSSION
MODERATOR
DR.ANIT PARIHAR
MD.PDCC
PRESENTER
DR.NABA KUMAR BARMAN
JR 1

2. Common Clinical Indications for abdominal x-ray
Abdominal pain+++
•Distention ++
•Vomiting +
•Ingestion of foreign body +++
•Possibility of intestinal obstruction +++
•Possibility of bowel perforation ++
•Placement of lines or tubes +++
•Organomegaly?? +/-

3. Radiographic principles
Series of films for acute abdomen
• Obstruction series/ Acute abdominal series/ Complete
abdominal series
– Supine (almost always)
– Upright or left decubitus (almost always)
– Prone or lateral rectum (variable)
– Chest, upright or supine (variable)

4. Obtaining views
• Supine
– Patient on back, x ray beam directed vertically downward, casette posterior, x
ray tube anterior (AP)
Prone
– Patient on abdomen, x-ray beam directed vertically downward, cassette
anterior, x-ray tube posterior (PA)
• Upright
– Patient stands or sits, x-ray beam directed horizontally, cassette posterior, x-
ray tube anterior (AP)
Upright chest
– Patient stands or sits, horizontal x-ray beam, cassette anterior, x-ray tube
posterior (PA)

5. Acute abdominal series
What to look for
Substitutes: Prone Lateral rectum
Upright Left lateral decubitus
Upright chest Supine chest
VIEW LOOK FOR
SUPINE ABDOMEN Bowel gas pattern
Calcifications
Masses
PRONE ABDOMEN Gas in rectosigmoid
Gas in rectosigmoid
Gas in ascending and
Descending colond
descending colon
UPRIGHT ABDOMEN Free air, air-fluid levels
UPRIGHTUPRIGHT CHEST
CHEST
FrFree air ,lung
pathology to intraabdominal
process

6. Approach to AXR
 Bowel gas pattern
 Extraluminal air
 Soft tissue masses
 Calcifications

7. Normal AXR
11th rib
Hepatic flexure
Gas in
stomach
T12
Gas in
caecum
Iliac crest
Femoral head
SI joint
Gas in sigmoid
Transverse colon
Splenic flexure
Psoas margin
Sacrum
Left kidney
Liver
Bladder

8. Gas pattern
 Stomach
Almost always air in stomach
 Small bowel
Usually small amount of air in
2 or 3 loops
 Large bowel
Almost always air in rectum
and sigmoid
Varying amount of gas in rest of large
bowel
What is normal?

9. Normal fluid levels
 Stomach
Always (upright, decub)
 Small bowel
Two or three levels
acceptable (upright, decub)
 Large bowel
None normally
(functions to remove fluid)

10. Large vs small bowel
 Large bowel
Peripheral (except RUQ occupied by liver)
Haustral markings don’t extend from wall to wall
 Small bowel
Central
Valvulae conniventes extend across lumen and are spaced
closer together

11. Abnormal Gas Patterns
 Functional ileus
One or more bowel loops become aperistaltic usually due
to local irritation or inflammation
Localised “sentinel loops” (one or two loops)
Generalised (all loops of large and small bowel)
 Mechanical obstruction
Intraluminal or extraluminal
Small bowel obstruction
Large bowel obstruction

12. 3, 6, 9 RULE
Maximum Normal Diameter of bowel
Small bowel 3cm
Large bowel 6cm
Caecum 9cm

13. Localised ileus
Key features
One or two persistently dilated
loops of small or large bowel
(multiple views)
Often air-fluid levels in
sentinel loops
Local irritation, ileus in same
anatomical region as
pathology
Gas in rectum or sigmoid
May resemble early SBO

14. Causes of Localised Ileus
by location
SITE OF DILATED LOOPS CAUSE
Right upper quadrant Cholecystitis
Left upper quadrant Pancreatitis
Right lower quadrant Appendicitis
Left lower quadrant Diverticulitis
Mid-abdomen Ulcer or kidney/ureteric calculi

15. Colon cut off sign
Abrupt cutoff of colonic gas column at the splenic flexure
(arrow). The colon is usually decompressed beyond this point

16. Generalised ileus
Key features
 Entire bowel aperistaltic/hypoperistaltic
 Dilated small bowel and large bowel to rectum (with LBO
no gas in rectum/sigmoid)
 Long air-fluid levels
CAUSE REMARK
*Postoperative Usually abdominal
surgery
Electrolyte imbalance Diabetic ketoacidosis
* almost always

17. Generalised adynamic ileus
The large and
small bowel are
extensively airfilled but
not dilated.
The large and
small bowel "look the
same".

18. Mechanical SBO
 Dilated small bowel
 Fighting loops (visible loops, lying transversely, with air-fluid
levels at different levels)
 Little gas in colon, especially rectum

19. SBO Erect SBO Supine
Air fluid levels

20. Causes of Mechanical SBO
* May be visible on AXR
Adhesions
Hernia*
Malignancy
Gallstone ileus*
Intussesception
Inflammatory bowel disease

21. Step ladder appearance
Loops arrange
themselves
from left upper
to right lower
quadrant in
distal SBO

22. String of pearls
sign
Considered diagnostic of obstruction (as opposed to
ileus)
and is caused by small bubbles of air trapped in the
valvulae of the small bowel.

23. Stretch/slit sign
Slit of air caught in a
valvulae, characteristic of
SBO

24. Mechanical LBO
Colon dilates from
point of obstruction
backwards
Little/no air fluid
levels (colon
reabsorbs water)
Little or no air in
rectum/sigmoid

25. Large bowel obstruction
Bowel loops tend not to
overlap therefore
possible to identify site
of obstruction
Little or no gas in small
bowel if ileocaecal valve
remains competent*
* If incompetent, large bowel
decompresses into small bowel, may
look like SBO

26. Thumbprinting
The distance
between loops of
bowel is increased
due to thickening of
the bowel wall.
The haustral folds
are very thick,
leading to a sign
known as
'thumbprinting.'

27. Causes of Mechanical LBO
TUMOUR
VOLVULUS
HERNIA
DIVERTICULITIS
INTUSSUSCEPTION

29. When the bowel measures more than the
interpedicular width of L2, it is said to be
dilated.
Massive dilatation is seen in complete
obstruction and is accompanied by fluid
levels on the dorsal decubitus radiograph.
However, fluid levels alone do not
necessarily correspond to dilatation, but
rather reflect abnormal peristalsis.
An unchanging bowel gas pattern over time
indicates absence of perstalsis.
IN CASE OF NEONATES

30. Double Bubble Sign
Duodenal Atresia

31. Closed loop obstruction
 Two points of same loop of bowel obstructed at a single
location
 Forms a C or a U shape
Term applies to small bowel, usually caused by
adhesions
Large bowel, called a volvulus

32. Note on volvulus
 Sigmoid colon has its own mesentry therefore prone to
twisting
 Caecum usually retroperitoneal and not prone to
twisting; 20% people have defect in peritoneum that
covers the caecum resulting in a mobile caecum

33. Volvulus
A volvulus always extends away from the area of
twist.Sigmoid volvulus can only move upwards and usually
goes to the right upper quadrant. Caecal volvulus
can go almost anywhere.

34. Coffee Bean Sign
Sigmoid volvulus
Massively
dilated
sigmoid
loop

35. Hernia
Lateral decubitus of value
The advantage is that there may be a greater chance of
air entering the herniated bowel because it is the least
dependent part of the bowel in the supine position.

36. Extraluminal air
• TYPES
– Pneumoperitoneum/free air/intraperitoneal air
– Retroperintoneal air
– Air in the bowel wall (pneumatosis intestinalis)
– Air in the biliary system (pneumobilia)

37. Upright film best
 The patient should be positioned sitting upright for 10-20
minutes prior to acquiring the erect chest X-ray image.
 This allows any free intra-abdominal gas to rise up, forming a
crescent beneath the diaphragm. It is said that as little as 1ml
of gas can be detected in this way.

38. Free Air
Causes
Rupture of a hollow viscus
Perforated peptic ulcer
Trauma
Perforated diverticulitis (usually seals off)
Perforated carcinoma
Post-op 5-7 days normal, should get less with
successive studies

39. Signs of free air
 Crescent sign
 Riglers (and False Rigler’s)
 Football sign
 Falciform ligament sign
 Triangle sign
 Cupola sign
 Lesser sac sign

40. Crescent Sign
Free air under the diaphragm
Best
demonstrated on
upright chest x
rays or left lat
decub
Easier to see
under right
diaphragm

41. Chilaiditis sign
 May mimic air under
the diaphragm
 Look for haustral folds
 Get left lat decub to
confirm

42. Rigler’s Sign
Bowel wall visualised on both sides due to intra and
extraluminal air
Usually large amounts of free air
May be confused with overlapping loops of bowel, confirm
with upright view

43. False Rigler’s Sign
 The Rigler sign can sometimes be simulated by contiguous
loops of bowel, whereby intraluminal air in one loop of bowel
may appear to outline the wall of an adjacent loop, which
results in a misdiagnosis of free air.
 Measure distance of interface if unsure

44. Football SIgn
Seen with massive
pneumoperitoneum
Most often in children
with necrotising
enterocolitis
Paediatric
Adult
In supine position
air collects anterior
to abdominal
viscera

45. Falciform ligament sign
Normally invisible.
Supine film, free air rises
over anterior surface of
liver

46. Other patterns of air around liver
Doge’s Cap Sign

47. Inverted V sign
 On the supine radiograph, an inverted "V" may be seen over
the pelvis in a patient with pneumoperitoneum.
 While in infants this is produced by the umbilical arteries, in
adults it appears to be created by the inferior epigastric
vessels

48. Continuous diaphragm sign
Sufficient
free air,
left and
right
hemi-
diaphrag
ms
appear
continous

49. Lesser sac Sign Cupola Sign
Lesser sac
sign
 (black
arrows)
The lesser sac is positioned
posterior to the stomach and
is usually a potential space.
There is free connection
between the lesser sac and
the greater sac through the
foramen of Winslow
Cupola
sign
– (white
arrows)
Air
superior
to left
lobe of
liver
Double Bubble Sign

50. Cupola Sign
The term cupola comes from a dome such as
this famous dome of the Duomo in Florence.
Air beneath the central tendon of the diaphragm

51. Triangle Sign
 The triangle sign refers
to small triangles of free
gas that can typically be
positioned between the
large bowel and the
flank

52. Retroperitoneal Air
• Recognised by:
– Streaky, linear appearance outlining retroperitoneal
structures
– Mottled, blotchy appearance
– Relatively fixed position
• May outline:
– Psoas muscles
– Kidneys, ureters, bladder
– Aorta or IVC
– Subphrenic spaces

53. Causes of retroperitoneal air
 Bowel perforation (appendix,
ileum, colon)
 Trauma (blunt or penetrating)
 Iatrogenic
 Foreign body
 Gas producing infection

54. Pneumoretroperitoneum
 This patient has free air in the
retroperitoneal space. The air is seen
surrounding the lateral border of the
right kidney (white arrow). There is
other evidence of free gas including
Rigler's sign.
 If you are not confident that the
appearance is pneumoretroperitoneum,
you can try an erect and decubitus view
to see if the gas moves. If the gas is
seen to move, it's not in the
retroperitoneum.

55. Air in the bowel wall
– Best seen in profile producing a linear lucency that
parallels the bowel
– Air en face has a mottled appearance resembling gas
mixed with faeculent material

56. Causes of air in bowel wall
 Primary Pneumatosis cystoides intestinalis (rare)
usually affects left colon
Produces cyst-like collections of air in the submucosa or
serosa
Secondary
Diseases with bowel wall necrosis
Obstructing lesions of the bowel that raise intraluminal
pressure
 Complications
Rupture into peritoneal cavity
Dissection of air into portal venous system

57. Pneumatosis intestinalis
 Intramural air

58. Air in the biliary tree
 One or two tube-like branching lucencies in the RUQ, conform to location of
major bile ducts

59. Causes
 “Normal” if Sphincter of Oddi incompetence
 Previous surgery including sphincterotomy or
transplantation of CBD
 Pathology (uncommon)
Gallstone ileus: gallstone erodes through wall of GB
into the duodenum producing a fistula between the
bowel and the biliary system.
Stone impacts in small bowel = mechanical SBO.
“ileus” misnomer

61. Biliary vs Portal Venous Air
 Portal venous air
usually associated
with bowel necrosis
 Air is peripheral
rather than central
 Numerous
branching
structures

62. Soft tissue masses
 Organomegaly
Know normal landmarks
2 ways to identify soft tissue masses/organs:
Direct visualisation of edges of structure
Indirect by displacement of bowel
CT, US and MRI have essentially replaced conventional
radiography in the assessment of organomegaly and soft
tissue masses

63. Location Pattern
Abdominal Calcifications

64. First exclude artefact
 Vascular
 Liver
 Gallbladder
 Spleen
 Pancreas
 Lymph nodes
 Adrenals
 Kidneys
 Ureters
 Bladder
 Prostate
Location

65. Rim-like
 Calcification that has occurred in the wall of a hollow
viscus
Cysts
renal, splenic, hepatic
Aneurysms
aortic, splenic, renal artery
Saccular organs
Gallbladder
Urinary bladder
Calcified hydatid cysts

66. Linear/Track
 Calcification in walls of tubular structures
Arteries
Fallopian tubes
Vas deferens
Ureter
Aortoiliac calcification

67. Chinese Dragon Sign
Calcified splenic artery

68. Calcified vas deferens

69. Floccular, Amorphous, Popcorn
 Formed in solid organ or tumour
Pancreas (chronic pancreatitis)
Leiomyomas of uterus
Lymph nodes
Metastases
Soft tissue (previous trauma, crystal deposition)

70. Calcified enteric
lymph nodes
Calcified fibroids
Calcified
pancreas
Floccular

71. Lamellar or laminar
 Formed around a nidus inside hollow lumen
 Concentric layers due to prolonged movement of stone inside
hollow viscus
Renal stones
Gallstones
Bladder stones

72. Bladder calculi
Lamellar

73. Staghorn Calcification
Renal stones are often small, but if large can fill the renal
pelvis or a calyx, taking on its shape which is likened to a
staghorn.Tubular

74. Nephrocalcinosis
Uncommonly the
renal parenchyma can
become calcified.
This is known as
nephrocalcinosis, a
condition found in
disease entities such
as medullary sponge
kidney or
hyperparathyroidism.
Renal calculi
Parenchymal calcification
Flocculent

75. Putty Kidney
 "Putty kidney" – sacs of
casseous, necrotic
material (TB)
 Autonephrectomy –
small, shrunken kidney
with dystrophic
calcification
Flocculent

76. Calcified gallstones
Lamellar

77. Conclusion
 Approach to AXR should include gas pattern, extraluminal air, soft tissue and
calcifications
 Named radiological signs are a useful way of remembering, identifying and
reporting on films
For acute abdominal pain in adults, an abdominal x-ray has a
low sensitivity and accuracy in general, as well as for specific conditions such
as gastrointestinal perforation, bowel obstruction, ingested foreign body, and
ureteral stones. particularly computed tomography after negative abdominal
ultrasonography, provides a better workup than projectional abdominal
radiography alone. Computed tomography provides an overall better surgical
strategy planning, and possibly less unnecessary laparotomies. Abdominal x-
ray is therefore less recommended for adults with acute abdominal pain
presenting in the emergency department.

78. References
http://www.radiologyassistant.org
 http://www.imagingconsult.com
 Begg abdominal xray .
 http://www.swansea-radiology.co.uk Radiology Teaching Site.
Introduction to abdominal radiology
 http://www.radiologymasterclass.co.uk/tutorials/abdo/abdo_x-
ray_abnormaliti
 http://www.learningradiology.com/radsigns
 http://www.radiopaedia.org

79. THANK YOU