Bowel Obstruction (Small and Large)

Bowel Obstruction (Small and Large) is a topic covered in the 5-Minute Emergency Consult.

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  • Obstruction of normal intestinal flow from mechanical or nonmechanical causes
  • Small-bowel obstruction (SBO):
    • 20% of acute surgical admissions
    • Adhesions: Most common cause (60%)
    • Neoplasms
    • Hernias
    • Strictures: Inflammatory bowel disease
    • Trauma: Bowel wall hematoma
    • Miscellaneous (e.g., ascaris infection)
  • Large-bowel obstruction (LBO):
    • Disease primarily of the elderly
    • Carcinoma (60%)
    • Diverticular disease (20%)
    • Volvulus (5%)
    • Colitis (e.g., ischemic, radiation)
    • Crohn's 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%)


  • Obstruction leads to proximal dilatation of intestines due to swallowed air and accumulated GI secretions, leading to increased intraluminal pressures.
  • Retrograde peristalsis causes vomiting.
  • Distended bowel becomes progressively edematous, and additional intestinal secretions cause further distention and 3rd spacing of fluid into the intestinal lumen.
  • Obstruction may lead to intestinal wall ischemia (strangulated obstruction), resulting in increased aerobic and anaerobic bacteria, and methane and hydrogen production. Peritonitis, sepsis, and death may follow.
  • Mortality is 100% in untreated strangulated obstruction, 8% if treated surgically within 36 hr, but 25% if surgery delayed after 36 hr.

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