Table IIIComputed tomography in acute bowel obstruction

  • Is 85–95% accurate in diagnosis of complete SBO
Simple SBO:
Open ended:
  • Marked discrepancy in caliber of proximal and distal bowel
Closed loop:
  • Fixed U-shaped or radial distribution of fluid filled bowel loops with the stretched and prominent mesenteric vessels converging towards point of torsion.
  • Whirl sign: tightly twisted mesentery around a collapsed segment of bowel
  • Beak sign: fusiform tapering of afferent and efferent limbs of bowel leading into site of obstruction.
  • Triangular, round or oval loops due to two adjacent collapsed loops despite proximally dilated loops
  • Anatomic segment involved
  • Tumor mass as lead point
  • Three concentric circles indicating segment of bowel invaginated into another
  • In intussuscepted MD, fat density (mesenteric fat at tip of MD) in Small Bowel lumen surrounded by edematous thickened bowel wall.
Complicated SBO:
  • Circumferential bowel wall thickening (> 3 mm)
  • Focal bowel dilatation
  • Increased attenuation of mesenteric fat
  • Target or halo sign: concentric ring of high and low attenuation of bowel wall
  • Pneumatosis intestinalis
  • Changes in the mesentery: increased haziness, blurring of vessels, and obliteration of fat due to hemorrhage
  • Ascites, or localized fluid collection with air bubbles (abscess)
  • Pneumoperitoneum
  • Adhesive obstruction: diagnosis based on not finding any other cause of obstruction
  • Gall stone ileus: air in biliary tree, contracted GB, air in GB, intraluminal calculus in SB, fluid filled bowel loops
  • Obstruction due to carcinomatosis: mass or bowel wall thickening along serosa of bowel at the transition zone
  • Crohn's disease: inflammatory mesenteric mass or discrete loculated fluid collection
  • Mural hematoma: Focal mass and depending on age of hematoma; density similar to circulating blood (early lesion), high density mass, or decreased density as clot lyses.
  • Sigmoid volvulous: whirl sign
  • Acute cholecystitis: enlarged thick walled gallbladder
  • Pancreatitis: swelling and fluid around pancreas
  • Mesenteric ischemia: thickened bowel wall, focal dilatation, pneumatosis
  • Acute diverticulitis: Thickened wall, mesenteric fat streaking, fluid collection, ascites
  • Acute appendicitis: inflammatory changes in fat around appendix; arrowhead sign

From: Small bowel obstruction

Cover of Surgical Treatment
Surgical Treatment: Evidence-Based and Problem-Oriented.
Holzheimer RG, Mannick JA, editors.
Munich: Zuckschwerdt; 2001.
Copyright © 2001, W. Zuckschwerdt Verlag GmbH.

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