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Small Bowel Obstruction (SBO)

Alex Wiles


  • Risk Factors: prior abdominal surgeries (adhesions), malignancy, hernia, intestinal inflammation (IBD)/stricture, radiation, abscess, foreign bodies
  • Indicators for bowel ischemia: fever, leukocytosis, tachycardia, peritonitis
  • Ddx: early appendicitis, large bowel obstruction, Ogilvie’s, DKA, Pancreatitis, IBD, Gastric outlet obstruction


  • Nausea, emesis, intermittent colic, bloating, constipation
  • Obstipation if completely obstructed, loss of flatulence
  • Exam: classically with “tinkling” bowel sounds, tympanic abdomen, distended abdomen


  • CBC, BMP, lipase, hepatic function panel, lactate (sensitive, not specific for ischemia)
  • Start with KUB to rule out perforation but typically will require CT (x-ray only ~80% sensitive)
  • CT abdomen/pelvis with IV contrast is optimal study if adequate renal function
    • No oral contrast (American College of Radiology (ACR) Appropriateness Criteria) as it will not aid diagnosis and can lead to aspiration; IV helps evaluate ischemia
  • Key word: transition point
  • Non-specific signs of bowel inflammation: bowel wall thickening, submucosal edema


  • Consult EGS: if any concern for SBO, evaluate need for urgent surgery
  • Surgical indications complete obstruction, CT with ischemia, perforation
  • Gastric decompression: place NGT (prevent aspiration)
  • NPO until obstruction relieved and NGT removed
  • Fluids: two large bore IVs (nursing communication); LR bolus + maintenance while NPO
  • If no resolution of partial obstruction at 48 hours:
  • Fluoroscopy Upper GI small bowel ft (follow through)
    • In comments, write “Gastrografin contrast” (water-soluble contrast) which osmotically reduces bowel wall edema and aids peristalsis
    • If gastrografin reaches the colon within 24 hours, it predicts clinical resolution of SBO without surgery
    • Note: this can also be therapeutic for pSBO and get bowels moving

Last update: 2022-06-13 16:57:02