Small Bowel Obstruction (SBO)

Matei Caleap

Background

  • Risk Factors: prior abdominal surgeries (adhesions) - most common cause 55-80% of cases, malignancy - 20% of cases, hernia – 10% of cases, intestinal inflammation (IBD)/stricture, radiation, abscess, foreign bodies, intussusception, volvulus.
  • Indicators for bowel ischemia: fever, leukocytosis, tachycardia, peritonitis.
  • Ddx: early appendicitis, large bowel obstruction (volvulus), Ogilvie’s, Ileus, DKA, Pancreatitis, IBD, Gastric outlet obstruction.

Presentation

  • Nausea, emesis, intermittent colic, bloating, constipation.
  • Obstipation if completely obstructed, no flatulence.
  • Exam: dehydration (tachycardic, orthostatic, decreased urine output), classically with “tinkling” bowel sounds, tympanic abdomen, distended abdomen.

Evaluation

  • CBC, BMP, lipase, hepatic function panel, lactate (sensitive, not specific), procalcitonin (new evidence w/ suggestion of sensitivity for intestinal strangulation).
  • Start with KUB to rule out perforation but typically will require CT (x-ray only ~80% sensitive) - CT abdomen/pelvis with IV contrast is preferred.
  • Fluoroscopic Small bowel follow-through gives functional info about SBO but NOT a primary modality for diagnosing acute SBO. 
  • Key word: transition point.
  • Non-specific signs of bowel inflammation: bowel wall thickening, submucosal edema.

Management

  • Consult EGS: if any concern for SBO, evaluate need for urgent surgery 
    • Surgical indications: complete obstruction, CT with ischemia, perforation, incarcerated hernia, intussusception 
  • Gastric decompression: place NGT 
  • NPO until obstruction relieved and NGT removed (bowel rest) 
  • 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 especially if SBO caused by adhesions. Not as much evidence supporting the effect of gastrografin within nonadhesive SBO
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