Small bowel obstruction

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Pearls

  • SBO without hx of sx, no hernia = malignancy until proven otherwise
  • "Never let the sun rise or set on a small bowel obstruction"


Causes

  • Postoperative adhesions
  • Malignancy
  • Hernias
  • Intraluminal strictures
  • Crohn's disease
  • Radiation therapy
  • Mesenteric ischemia
  • Trauma (particularly to the duodenum)
  • Gallstone ileus


Clinical Manifestations

  • Nausea/vomiting
  • Seen more in proximal than distal obstruction
  • Abdominal distention
  • Seen more in distal than proximal obstruction
  • Abdominal pain
  • Typically crampy, periumbilical
  • Paroxysms of pain occur q5min
  • Inability to pass flatus
  • Pts may pass flatus/stool initially
  • Takes 12-24hrs for colon to empty
  • Dehydration
  • Anorexia
  • Metabolic alkalosis
  • Strangulation may occur
  • Fever
  • Leukocytosis


Laboratory Diagnosis

  • CBC - evidence of strangulation?
  • Chem - degree of dehydration, evidence of ischemia (acidosis)
  • Lactate -Sensitive (90-100%), though not specific, marker of strangulation


Imaging

  • Acute abdominal series
  • Upright chest film: r/o free air
  • Upright abd film: air-fluid levels
  • Supine abd film: width of loops of bowel most visible (estimate of amount of distention)
  • Presence of air in colon or rectum makes complete obstruction less likely (esp of symptoms > 24hr)
  • If pt cannot be placed in upright position a left lateral decub abd film can substitute


  • CT A/P with PO and IV contrast
  • Consider if plain films are non-diagnostic
  • Can show closed-loop obstruction, evidence of ischemia


Management

  • IV fluid resuscitation with electrolyte repletion
  • Assessment of need for operative vs nonoperative management
  • Nonoperative Management
  • Sometimes successful in patients with partial SBO (must rule-out strangulation first!)
  • IV fluid resuscitation with electrolyte repletion
  • NG tube
  • 14 French
  • Intermittent low wall suction
  • Nasogastric fluid losses can be replaced w/ NS + KCL (30-40 meq)
  • Contrast
  • Both diagnostic and therapeutic (draws water into the bowel stimulating peristalsis)
  • Associated with decreased hospital stay, more rapid resolution of symptoms
  • If increasing pain, distention, or peristent high NGT output, consider operative intervention
  • Repeat CT scan may be helpful to detect early signs of bowel ischemia
  • Repeat plain films are not helpful (only detect perforation)
  • Operative Management
  • 25% of pts admitted for SBO require surgery
  • Indicated for pts with:
  • Complete SBO
  • Closed-loop obstruction
  • Fever, leukocytosis, peritonitis


Source: UpToDate