1. Bowel Ischemia Dr. Ahmed Refaey Consultant radiologist
Riyadh Military Hospital
MBBCh, MS, FRCR

2. Blood supply

3. Blood supply of small intestine
The entire small intestine is supplied by the superior mesenteric artery and drain to the superior mesenteric vein, which in turn drains to the portal vein.

4. The arterial supply of the colon
That right part of the colon to the midtransverse colon is supplied by the superior mesentric artery
The inferior mesenteric artery supplies the colon as far as the upper rectum

5. Venous drainage of the colon
Veins corresponding with arteries drain to the superior and inferior mesenteric veins.

6. Blood supply of large intestine

7. Etiology

8. Risk factors * atrial fibrillation/flutter
* recent acute myocardial infarction
* hypovolemia or hypotension ( sepsis )
* coagulation disorders or malignancy
* portal hypertension/ cirrhosis
* medications
- vasopressin-digitalis-beta blockers

9. Pathogenesis
Mesenteric arterial or venous narrowing or occlusion leading to inadequate supply of oxygen to the bowel.

10. Classification

11. Bowel ischemia Acute or chronic Occlusive or nonocclusive
Arterial or venous
Small bowel or large bowel .
{{ ischemic enteritis or ischemic colitis }}.

12. Acute ischemia Acute interruption of blood flow to the bowel causes :
@ arterial
_ occlusive
* embolism {40-50%} : atrial fibrillation or endocarditis
(SMA most commonly involved)
* thrombosis { 20-40% } : atherosclerosis
* mechanical obstruction: strangulation, tumor
_ nonocclusive
hypoperfusion ( low flow states, hypotension, sepsis or
heart failure with diffuse mesenteric vasoconstriction )
( IMA most commonly involved )
@ venous
* Mesenteric venous thrombosis { 10% }

13. .
Arterial sources occur more frequently than venous sources by a ratio of 9:1
Similarly, arterial occlusive disease occur more frequently than nonocclusive disease by a ratio of 9:1
Large or smaller segments of bowel may be involved, depending on the location of the occlusion
Regardless the mechanism, the disease follows the same course.

14. .
Clinical details :
* clinical triad of {sudden onset of abdominal pain, diarrhea & vomiting}
* diffuse abdominal pain, out of proportion to physical examination.
* leukocytosis
* gross rectal bleeding

15. . Chronic ischemia. { abdominal angina}
* * most commonly caused by atherosclerosis of coeliac and SMAs & symptoms are unlikely unless at least two vessels are involved.

16. .
** clinical details
* post-prandial abdominal pain, minutes after food intake ( due to “gastric steal” diverting blood flow away from intestine ) and the pain subsides 1-2 hours after meal.
* fear of eating large meals
* malabsorption
* weight loss

17. Pathophysiology of bowel ischemia
Mucosa is most sensitive area to anoxia from arterial / venous occlusion with early ulceration, later on necrosis and perforation occur.( of clinical importance )
Ischemia causes increased permeability of capillaries resulting in both submucosal edema and hemorrhage.( of radiological importance )

18. Ischemic colitis
Most cases are thought to be related to diminished blood flow within the bowel
Predominantly a disease involving the distribution of IMA .i.e., from distal transverse colon to rectum
When the more proximal colon is involved, it is frequently associated with extensive small bowel ischemia & a correspondingly much graver prognosis.
Patients are usually elderly .
The clinical picture may mimic acute diverticulitis.
Most common cause of colitis in elderly & is often self limiting.

19. . Prognosis of ischemic colitis
complete resolution (75%) within months
Stricturing ischemia (20%)
Gangrenous with necrosis and perforation (5%)

20. Imaging

21. Imaging
Plain abdominal radiography
Barium study
Angiography CT

22. Imaging Plain abdominal radiograph * abnormal in 20-40%
* thumbprinting ( non specific finding, indicating intestinal wall edema with haemorrhage
* pneumatosis
* PV gas
* pneumoperitoneum
( all indicative of bowel infarction)

23. SMA thrombosis

24. .
81 y old woman with myocardial infarction. Plain abdominal radiograph shows air in the wall of right colon and small & large bowel dilatation.

25. Barium study

26. Barium study * small bowel 1 - thick, smooth valvulae conniventes.
2 - Barium trapped between the thick folds produces the “ interspace spicking”
3 – (1:2) cm submucosal fluid or blood collections can form, known as “ thumbprinting”

27. . Thick, smooth valvula connivents (black arrows)
Interspace spicking (white arrows)
Thumbprinting
(arrow head)

28. .

29. . * large bowel 1- thumbprinting (75%) 2- ulceration
3- loss of interhaustral folds
4- luminal narrowing
5- confined to left hemicolon (90%)

30. .
Segmental narrowing of the entire transverse colon . Within the narrowed segment, there are multiple thumbprinting indentations

31. .
Postischemic stricture , contain pseudodiverticula

32. CT

33. CT Examination of choice Sensitivity more than 95% ( MDCT )
Identifies or excludes other pathologies
Delineates cause,severity and complications.
Guides management

34. Acute ischemia, why CT ?
Plain film– 33% sensitivity – non specific –no information on causes, severity.
Barium study – do NOT do , non-specific, interfere with CT
Angiography – technically difficult, invasive, contraindicated in hypotensive patients

35. CT technique MDCT “if possible”
Water oral contrast {1000 cc} “ not positive OC “
IV contrast : 3-5 ml/sec
Arterial and PV phase

36. .

37. CT findings Suggestive signs
1* “double halo” or “ target” sign. ( edema of
the submucosa –low attinuation- with
brighter mucosal and serosal surfaces in CECT )
2* circumferential bowel wall thickening
3* focal / diffuse bowel dilatation
4* increased attinuation of mesenteric fat ( edema )
5* pneumatosis intestinalis
6* pneumoperitoneum
7* ascites
8* variable enhancement pattern

38. .
highly suggestive signs:
1- bowel wall thickening with dilatation

39. . reliable signs: 1- thromboembolism in mesenteric vessels.
2- lack of enhancement of the ischemic segment of bowel.
3- Portal venous & mural gas.

40. .
A reliable method to differentiate arterial causes from venous causes is depiction of the characteristic bowel wall enhancement pattern. Arterial occlusive disease demonstrate no enhancement of the involved segment, whereas venous occlusive disease or hypoperfusion reveal marked contrast enhancement and retention 2ry to stagnant flow, with thickening of bowel wall.

41. .

42. Differential diagnosis

43. * Causes of intramural edema ( hypoprotinemia, lymphatic blockage 2ry to tumor, inflammatory infiltrate like graft vs host disease and esinophilic enteritis.
Inflammatory bowel disease (Crohn disease-UC)
Infectious bowel diseases
Causes of intramural hemorrhage:
1-ischemia
2-radiation
3-vasculitis –CT disease( SLE, RA,Henoch Schonlein purpura)
4-bleeding : from hemophilia, thrombocytopenic purpura, anticoagulant therapy, DIC.

44. illustrated cases

45. .
SBFT shows “stack of coins” small bowel fold pattern due to ischemia,intramural hge.

47. .
Axial CECT in 23 y old woman with hypercoagulable state + bowel ischemia. Dilated fluid filled small bowel + thrombosis of SMV.

48. .
Axial CECT shows dilates small bowel with areas of wall thickening (arrow). Patient has severe abdominal pain. Bowel infarction from atrial fibrillation.

49. .
Patient with acute ischemia , grossly thickened wall of the splenic flexure and descending colon. There is intraperitoneal air in the subhepatic region & Morrison’s pouch.

50. CT demonstrate distension of the caecum
CT demonstrate distension of the caecum. The bowel wall is thickened, and contains multiple small intramural gas bubbles. .

51. .
CT scan shows thickening of the transverse colon . These findings suggest a distribution in superior mesenteric artery territory.

52. .
CT confirms the presence of air in the portal venous system and proximal small bowel mucosal edema. These findings suggest ischemia of the affected bowel.

53. . Top CT image shows gas in the portal venous system (blue circle).
Center image shows thrombosed SMA (blue arrow) .
Lower cuts show extensive pneumatosis intestinalis.

54. SMV thrombosis

55. Ischemic colitis
The enema confirms the appearance of mucosal thickening and localizes the affected bowel to distal transverse colon , splenic flexure and proximal descending colon

56. Ischemic colitis
The enema confirms the appearance of mucosal thickening and localizes the affected bowel to distal transverse colon , splenic flexure and proximal descending colon.

57. .
Pneumatosis coli

58. .
Splenic flexure to descending colon watershed
Ischemic colitis

59. .
Abscent enhancement
IMA occlusion {left colic bransh}

60. .
SMA embolus

61. .
SMV thrombosis

62. Ischemic colitis
CT image in 22 y old woman with ischemic colitis after blunt abdominal trauma to right flank demonestrate marked thickening of hepatic flexure and right colon, with abrupt transition (arrows) between abnormal and normal wall in the transverse colon.

63. . Diffuse wall thickening of all colon. 50 y old male
Diarrhea, abdominal pain, fever, leukocytosis
Antibiotic (cephalosporin) treatment since 2 weeks
Pseudomembranous colitis

64. .
Marked low attinuation caecal wall thickening as well as proximal transverse colon with moderate pericolonic inflammatory stranding
45 y old male
Bloody diarrhea/ abdominal pain/ fever/vomiting.
History of leukemia
Neutropenia
Typhlitis ( neutropenic colitis)

65. . 18 y old female Small bowel wall thickening ( not dilated)
Mesenteric inflammatory stranding
Mesenteric adenopathy
Crohn’s disease

66. . 15 y old boy Circumferential wall thickening of ascending colon
Pericolic inflammatory mesenteric fat stranding
Crohn’s disease

67. .
Axial CECT shows narrowed lumen and thickened wall of descending colon . Submucosal halo of low density (edema) and engorged blood vessels indicate active disease.
Ulcerative colitis

68. .
Axial CECT shows mural thickening of ascending + transvrse colon plus dilated mesenteric vessels.
Infectious colitis ( campylobacter colitis)

69. . Diffuse colonic wall thickness Antibiotic treatment since 10 days
Pseudomembranous colitis

70. .
Thumbprinting of transverse colon
Ulcerative colitis

71. . Pancolitis Diffuse wall thickening of all colon
Pseudomembranous colitis.

72. Complications
Sepsis
Septic shock
Multiple system organ failure
death

73. Mortality

74. .
Occlusive mesenteric infarction { embolus or thrombosis } has a 90% mortality rate , whereas non-occlusive disease has a 10% mortality rate .
Ischemic enteritis % mortality rate
Ischemic colitis % mortality rate

75. Conclusion

76. The diagnosis of mesenteric ischemia often is a challenge to both clinicians and radiologists . Patients with inflammatory bowel disease and infectious colitis can present with similar physical signs and symptoms, including cramping abdominal pain ,bloody diarrhea & leukocytosis.
Bowel wall thickening is a finding common to all 3 types of disease, however,the pattern of vascular distribution can sometime narrow the differential diagnosis. .

77. . Ischemic bowel disease is a clinico-radiological diagnosis
High clinical suspecion is key to early diagnosis
Prognosis depends on underlying cause not imaging.

78. Many classifications for bowel ischemia
{ arterial or venous}
{ occlusive or nonocclusive}
{ small or large bowel}
{ acute or chronic}
Regardless the mechanism, the disease follows the same course.
Clinical picture is very important
Vascular supply is important ( location predicts distribution)
CT findings are important { highly suggestive & reliable}
DD: inflammatory & infectious bowel diseases- diseases causing submucosal hge and edema.

79. thank you