Bowel Obstruction (Small and Large)



  • Obstruction of normal intestinal flow from either mechanical or nonmechanical causes, affecting either the small or large intestine
  • Can be classified into small bowel obstruction (SBO), large bowel obstruction (LBO), and nonmechanical or functional causes
  • Also classified as either partial, complete, or closed-loop obstruction
  • Obstruction leads to proximal dilatation of intestines due to swallowed air and accumulated GI secretions, leading to increased intraluminal pressures and vomiting
  • Distended bowel becomes progressively edematous, and additional intestinal secretions cause further distention and third spacing of fluid into the intestinal lumen
  • Obstruction may lead to intestinal wall ischemia (strangulated obstruction), resulting in increased aerobic and anaerobic bacteria possibly leading to peritonitis, sepsis, and possibly death
  • Closed loop obstruction: Distal and proximal obstruction leading to more rapid increase in intraluminal pressures and arterial/venous congestion making higher risk for bowel infarction
  • Mortality is 100% in untreated strangulated obstruction, 8% if treated surgically within 36 hr, but 25% if surgery delayed after 36 hr


  • SBO:
    • 20% of acute surgical admissions
    • More common than LBO
    • Adhesions: Most common cause (60%)
    • Neoplasms
    • Hernias
    • Strictures: Inflammatory bowel disease
    • Trauma: Bowel wall hematoma
    • Miscellaneous (e.g., ascaris infection)
  • LBO:
    • Disease primarily of the elderly
    • Carcinoma (60%)
    • Diverticular disease (20%)
    • Volvulus (5%)
    • Colitis (e.g., ischemic, radiation)
    • Crohn disease
    • Foreign bodies
  • Functional, nonmechanical:
    • Paralytic ileus (e.g., electrolyte abnormalities, injury)
    • Pseudo-obstruction (i.e., Ogilvie syndrome [e.g., operative and nonoperative trauma] 11%)

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