1. DR MOSES ACAN DEPARTMENT OF RADIOLOGY
The ACUTE ABDOMEN
DR MOSES ACAN
DEPARTMENT OF RADIOLOGY

2. Definition Acute abdominal pain Is Pain unrelated to trauma
It is one of the most common conditions in patients presenting to the hospital emergency department.
It is a syndrome characterized by the sudden onset of severe abdominal pain, requiring early medical or surgical treatment

3. The Abdominal Series
For all acute abdominal complaints where plain film imaging is indicated, get a COMPLETE abdominal series
Exceptions: Suspected renal calculus or foreign body, where a single view is OK
CT and ultrasound are often performed after plain films

4. Abdominal Series Indications:
Highest yield: Presentations suggestive of free air or obstruction
Not very good for masses, ascites, organomegaly, biliary tract disease, GI bleeding and vague abdominal complaints
Yield is higher in the elderly

5. The Abdominal Series Erect chest, AP supine and erect abdomen
Or, if patient unable to sit/stand:
supine chest, supine and left lateral decubitus abdomen
For calculus or foreign body: AP supine abdomen

6. The Erect Chest Best for free air
To evaluate for intrathoracic abnormalities presenting with abdominal complaints, especially pneumonia (more common in kids)

7. Supine Abdomen
Best for abdominal detail: Organs, bones and joints, calcifications, fat and gas pattern

8. Erect Abdomen
For air-fluid levels and little else

9. Left Lateral Decubitus Abdomen
Substitute for erect chest (free air) and erect abdomen (air-fluid levels) in a patient unable to sit or stand

10. Indications for a single erect abdomen film ONLY
NONE
None

11. The Check List Bones and joints Calcifications Organs Fat
Gas: In bowel and outside of bowel

12. A memory aid “First organs, bones, and stones,
Then masses, fat, and gas.
Don’t forget the corner zones,
And you’ll always cover your…subject”

13. The Normal Abdominal Series
Chest
Supine abdomen
Erect abdomen
Left lateral decubitus abdomen

14. Chest

15. Supine Abdomen

16. Erect Abdomen

17. Left Lateral Decubitus Abdomen

18. In the gut, and elsewhere
GAS
In the gut, and elsewhere

19. FREE AIR: Perforated Gut
PNEUMOPERITONEUM
FREE AIR: Perforated Gut

20. Free Air Best views: Erect chest and left lateral decubitus abdomen
Erect abdomen is less sensitive
Supine abdomen is insensitive

21. How Sensitive? Plain films are 85% sensitive for free air
Theoretical threshold is 2 cc
CT is much more sensitive and is the “Gold Standard”

22. Signs Air beneath diaphragm Both sides of bowel walls (Riglers sign)
Falciform ligament , medial and lateral umblical ligaments and the urachus
In the biliary system
Air in the Morisons pouch
Cupula sign
Football sign

23. Free Air: Erect Chest Air under the diaphragm Usually on the right
Occasionally only seen on the left

24. Free Air: Erect Chest

25. Free Air: Left Lateral Decubitus
Right side up, left side down
Patient who can’t sit or stand
Air under right abdominal wall

26. Free Air: Left Lateral Decubitus

27. Free Air: Supine Abdomen
Double bowel wall sign

28. Bile ducts Gall bladder
Air in Biliary System
Bile ducts
Gall bladder

29. Air in Biliary System Usually secondary to surgery on bile ducts
Can be due to biliary-bowel fistula from infection or neoplasm
Rarely, can be due to infection

30. Air in Bile Ducts/gall bladder

31. A sign of dead or dying bowel
Portal Venous Air
A sign of dead or dying bowel

32. Portal Venous Air

33. Gas and Fluid Too Much and Too Little
The GUT
Gas and Fluid
Too Much and Too Little

34. The Gas Pattern Can be specific for obstruction
Often, nonspecific: General ileus, focal ileus, ischemia, or obstruction
A paucity of gas may be due to vomiting or fluid-filled bowel

35. OBSTRUCTION
Small bowel
Colon

36. Small Bowel Obstruction: Causes
Small bowel obstruction much more common than colon: 70:30
Causes
Adhesions 80%
Hernia 15%
Tumors, intussusception, midgut volvulus, etc.

37. Small Bowel Obstruction: Findings
Step-ladder dilated bowel loops on supine view
Step-ladder air-fluid levels on erect/decubitus views
Stretch sign on supine view
String-of-pearls sign on erect/decubitus views

38. Ultrasound
Can demonstrate dilated fluid filled loops of small bowel obstruction
Assessment of peristalsis can be made at the same time
CT scan is increasingly being used
It is capable of demonstrating bowel caliber change and the level
Fluid filled loops are clearly visible
The level of obstruction can be identified

39. How Big is Big?
In an adult, any visible small bowel is abnormal, but small amounts often not significant. Kids normally have small amounts.
Jejunum over 3 cm and ileum over 2 cm diameter is very abnormal, but not specific for obstruction

40. Air, Fluid or Both?
Small bowel can be distended by either air or fluid or both
Fluid-filled bowel may be more significant than air-filled bowel, but often the significance is the same

41. Air Filled Small Bowel

42. Fluid Filled Small Bowel

43. Air-Fluid Levels
Always abnormal in small bowel, but not specific; often normal in colon
The height of the fluid levels, same or different, is NOT helpful in distinguishing ileus from obstruction

44. Small Bowel Air-Fluid Levels

45. What is Dilated?
If small bowel and colon dilated equally, probably not small bowel obstruction: nonspecific ILEUS
If small bowel significantly more dilated than colon, suggests SBO
Some gas in colon does NOT exclude SBO

46. Ileus

47. Classic Small Bowel Obstruction, Supine

48. Classic Small Bowel Obstruction, Erect

49. Stretch Sign: Supine

50. String-of-Pearls Sign: Erect

51. COLON Obstruction Causes
Carcinoma of the colon 80%
Volvulus 5%
Diverticulitis 5%
Fecal impaction 5%
Everything else 5%

52. Colon Obstruction: Carcinoma

53. Colon Obstruction: Volvulus
5% of total
80% sigmoid
20% cecum

54. Volulus: Sigmoid Specific signs include: - coffee bean sign
- Frimann Dahl's sign - three dense lines converge towards site of obstruction
absent rectal gas

55. Volvulus: Cecum Radiologically
Large gas filled and fluid filled viscus situated almost anywhere in the abdomen
Identification of an attached gas filled appendix confirms the diagnosis
Moderate or severe small bowel distension is found in about ½ of cases
The left half of the colon is usually collapsed

56. Colon Obstruction: Measurements
The cecum is the most distensible part of the colon
A cecum of 9 cm diameter is cause for concern
A cecum of 11 cm is impending perforation

57. Other Emergency Conditions of the Gut
Toxic megacolon: Crohn, UC; 5cm transverse colon is impending perforation
Enterocolitis: C. diff. and other microbes
Ischemia

58. A word on Thumbprinting
It means thickened bowel wall
It can occur acutely in C. diff. or ischemia or hemorrhage
Chronically, it can be seen in inflammatory bowel disease and neoplasm and a few other less common diseases

59. C. diff. Enterocolitis

60. Ischemic Bowel Disease
Arterial emboli
Arterial thrombi
Venous thrombi: Hypercoag., neoplasm
Non-occulsive mesenteric ischemia: Low flow states

61. Ischemia: Findings Normal gas pattern Non-specific ileus Thumbprinting
Gas in bowel wall
Gas in portal vein system
Free air

62. Ischemia: Thumbprinting

63. ACUTE APPENDICITIS

64. Ultrasound in acute appendicitis; graded compression technique
Blind ending tubular structure at the point of tenderness
Non compressible
Diameter 7mm or greater
No peristalsis
Appendicolith casting acaustic shadow
High echogenicity non compressible surrounding fat
Surrounding fluid or abscess
Oedema of caecal pole

65. CT in acute appendicitis – is highly accurate
An appendix measuring greater than 6mm in diameter
Failure of the appendix to fill with oral contrast or air upto its tip
An appendicolith
Enhancement of its wall with contrast
Surrounding inflammatory changes
Increased fat attenuation
Fluid
Inflammatory phlegmon
Caecal thickening
Abscess
Extraluminal gas
Lymphadenopathy
The “arrow head sign” Sometimes the lumen of the caecum can be seen pointing towards the obstructed opening to the appendix

66. Acute Appendicitis: CT

67. Focal Ileus and appendicolith

68. Gall Bladder Disease

69. Acute Cholecystitis
Almost all cases are associated with gallstones and most are caused by obstruction of the cystic duct
Only about 20% of gall stones contain sufficient calcium to be visible on plain radiographs and only rarely does the wall of the gallbladder itself calcify

70. Inflammation- Cholecystitis
Ultrasound is the preferred imaging method to confirm cholecystitis in the appropriate clinical setting.
Hypoechoic margin
Indistinct contour of the gallbladder wall and fluid around the fundus of the GB
Gallstones which cast acaustic shadows
A stone obstructing the cystic duct producing a grossly dilated GB
Echogenic sediment seen in the lumen caused by inspissated bile or pus
Tenderness of the GB (positive Murphy sign)

71. Cholelithiasis: Ultrasound

72. Cholelithiasis

73. PANCREATITIS
Acute

74. Acute Pancreatitis
Clinical diagnosis is extremely difficult in the initial stages with perforated PUD and acute cholecystitis as differentials
Alcohol abuse and gallstones are the commonest causes
Other causes include trauma, cryptogenic, tumor, infection, hyperlipidemia, and ERCP.

75. Ultrasound findings
Pancreatic enlargement with indistinct boundaries
Diminished echogenicity due to oedema
Duodenal atony and wall thickening
With necrotizing pancreatitis
Liquid or semifluid tissue may be identified spreading beyond organ boundaries
Pleural effusion and ascites may be detected
State of the biliary tree (dilatation if obstruction is present)

76. Pancreatitis
CT Findings typical of pancreatitis include: necrosis, hemorrhage and solid parenchyma that enhance with i.v contrast 1. An enlarged pancreas with infiltration of the surrounding fat 2. Peripancreatic fluid collections can often be seen 3. Pseudocysts, (encapsulated fluid collections containing pancreatic secretions, are later complications of pancreatitis) CT is also useful for assessing patients with complications of acute pancreatitis pseudocysts, abscess, hemorrhage, necrosis and ascites

77. Notice the peripancreatic stranding (bars) as well as the fluid thickening of the interfascial space

78. A common complication of pancreatitis is the development of pancreatic necrosis. Lack of gland enhancement following IV contrast administration is diagnostic. When over half the pancreas becomes necrosed, the mortality rate may reach as high as 30%.

79. Pancreatic pseudocyst

80. Chronic Pancreatitis

81. Abdominal Aortic Aneurysm

82. AAA Plain films are not sensitive, but can be diagnostic
Calcified walls of aorta can allow measurement of lumen
AAA if over 3 cm AP diameter
Ultrasound and CT are much more sensitive

83. AAA

84. AAA: CT

85. The odd and the interesting
A few more…
The odd and the interesting

86. Echinococcus cyst

87. Foreign Body: Battery

88. Tongue Ornament Misadventure

89. Body Packer or Mule