Many Faces of Bowel Obstruction.

1. Many Faces of Bowel Obstruction
Prof. Raju Sharma
All India Institute of Medical Sciences, New Delhi

2. Bowel Obstruction
 Wide variety of causes
 Non-specific clinical manifestations: pain, vomiting, distension, decreased
passage of stool & flatus
 Pain out of proportion to exam. findings s/o strangulation
 Imaging plays a vital role
 Time is critical
 Reliance on imaging has steadily increased
 Qs: Sx or not?
 Expectations are very high!

3. IMAGING MODALITIES
 Plain radiograph (supine/erect)
 Ultrasonography- children, pregnant women
 Computed Tomography- modality of choice
 CT Enterography in low grade obstruction
 Magnetic Resonance Imaging – seldom used

4. Computed Tomography
 Modality of choice
 Global perspective of entire abdomen
 Uninhibited by bowel gas & fat
 Transition point, cause, vascular compromise
 MDCT: thin collimation, MPRs
 Oral contrast: not useful in emergent situation
 I.V contrast mandatory unless CI
 CT Angiography: bowel ischemia
 Radiation concern: ASIR, low dose protocols

5. Bowel Obstruction
 Accounts for 20% of acute abdominal surgical condition
 Small bowel obstruction 4 to 5x more common than large
 Common causes: adhesions, hernia, volvulus, inflammatory strictures,
neoplasms, intussusception, ischemic
 Intraluminal/ Intramural/ Extrinsic
 Acute/Subacute/Chronic
 Simple/Strangulated
 Complete/Incomplete
 Open/Closed loop

6. Plain Radiographs
 Supine, erect, chest radiographs
 Utility of erect radiograph?
 If severely ill- lateral decubitus abdominal radiograph
 Moderate sensitivity 40-80%
 Dilated loops > 3cm
 Air fluid levels: >2.5 cm, at disparate levels
 Transition point is important
 D/D: Paralytic ileus

7. Plain Radiographs
Mechanical Obstruction
Paralytic Ileus
Pseudo-obstruction
Small Bowel
Proximal/Distal Large Bowel
Acute/Subacute
Partial/Complete
Simple/Strangulated
Open/Closed loop
Ischemia/ PerforationEtiology
CT

8. Causes of Small Bowel Obstruction
 External hernias
 Adhesions
 Malrotation, bands
 Internal hernias
 Peritoneal Carcinomatosis
 Gall stone ileus
 Parasites
 Foreign body
 Ulcero-constrictive lesions
 Intussusception
 Tumors
 Carcinoma
 Carcinoid
 Radiation
 Ischemia
Extrinsic
Intra-luminal
Intrinsic

9. Small Bowel Obstruction Large Bowel Obstruction

10. Large Bowel Obstruction
• Cecum has the widest diameter – develops the maximum tension in the wall
• Risk of perforation ↑ when diameter > 9 cm

11. Pneumoperitoneum

12. • CT has sensitivity of 81-94% &
specificity of 96% for high grade
obstruction
• Dilated bowel with transition point
• Small bowel faeces sign close to
transition point
• Evaluate for hernia, volvulus,
ischemia

13. Closed Loop Obstruction
 2 points along the course of bowel are obstructed
at single location
 More than one transition zone
 Affected loops are markedly dilated (>4cm) with
fluid
 Fusiform tapering at point of twist
 Stretched mesenteric vessels converging to a point
 Vascular supply may get compromised: prompt
surgery

14. MRI

15. Signs of Vascular Compromise
 Clinical signs like fever, tachycardia, acidosis are not reliable
 Meta-analysis found CT sensitivity of 83% and specificity 92%
 Bowel wall edema or hemorrhage
 Altered bowel wall enhancement: ↑ enhancement then ↓
 Mesenteric fluid & stranding
 Vascular engorgement
 Pneumatosis, free intraperitoneal air, portal venous gas
 Certain causes have higher likelihood of vascular compromise: closed loop,
volvulus, hernia, obstructing mass

17. Bowel Ischemia

18. 58 yr male with acute pain abdomen

19. Mesenteric Venous Ischemia

20.  Usually a diagnosis of exclusion, kinking or tethering of loops
 Form in 90% abdominal surgeries but only 5% complicated by SBO
 Highest incidence after colo-rectal surgery
 1% of patients develop obstruction in immediate post-op period -90% of
are due to adhesions
 Signs for predicting need for surgery:
 Free intra-peritoneal fluid
 Mesenteric fat stranding
 High grade obstruction
 Absent small bowel feces sign
Adhesive Obstruction

21. Adhesive Obstruction

22. Ileo-Cecal Tuberculosis

24. Inflammatory Stricture

25. Duodenal Tuberculosis
• 2% of GI TB
• 3rd part most common
• Ulcerative type or hyperplastic
• Healing with fibrosis may lead to duodenal
obstruction

26. Crohn’s Disease

27. Chronic Fibro-stenotic Disease

28. Hernia Causing Obstruction
 Internal/ External
 Inguinal (80%)/ Femoral (5%)/ Obturator/ Ventral/ Spigelian
 Hernial sites should be included on plain radiographs
 Inferior epigastric artery is landmark to differentiate indirect/ direct IH
 Femoral hernia is seen anteromedial to femoral vein, more common in
women, more prone to strangulation
 Obturator hernia: more common in elderly women, between the pectineus
and obturator externus

29. Obstructed Right Inguinal Hernia

30. 80 yr lady: Obturator hernia

32. Intussusception

33. 70 yr old male patient with vomiting & abdominal distension

36. Small Bowel Obstruction due to Intussusception Caused by GIST

37. Intussusception Causing Obstruction & Ischemic Bowel

38. Adenocarcinoma
• Duodenal/ Jejunal location
• Annular/ Polypoidal/ Asymm. wall thickening
• Obstruction is common

39. 25 year male with recurrent pain abdomen

40. Midgut Volvulus

43. Sclerosing Encapsulating Peritonitis

44. Ascariasis

45. Gall Stone Ileus: Riggler Triad

49. Post-Gad
Mesenteric Lymphangioma causing SBO due to Volvulus

50. Mesenteric lymphangioma causing volvulus

51. Causes of Large Bowel Obstruction
 Sigmoid volvulus
 Cecal Volvulus
 Tumors: 55%
 Diverticulitis: 12%
 Intussusception
 Tuberculosis
 Ischemic strictures
 Stercoral colitis/ulcer
10%

52. Large Bowel Obstruction

53. Volvulus
Caecal Sigmoid

54. 70 year old man with constipation and vomiting

57. Adenocarcinoma Sigmoid Colon

59. Diverticulitis
• Bowel wall thickening, peri-colonic
inflammation, diverticulosis
• Inflamed diverticuli may be
hyperdense on CT
• Sigmoid colon: most often involved
• Hinchey’s classification
• Perforated malignancy may mimic
perforated diverticulitis

61. Sigmoid Perforation

62. Conclusion
 Confirm bowel obstruction
 Small bowel or large bowel
 Likely etiology
 Is strangulation / perforation present
 Increasing shift towards conservative management in uncomplicated SBO
 If CT features point towards vascular compromise – urgent surgery
 In conjunction with clinical signs guide management
 Early diagnosis is critical

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64. Thank you for your attention!