Small bowel obstruction

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

1. Postoperative adhesions
2. Malignancy
3. Hernias
4. Intraluminal strictures
   1. Crohn's disease
   2. Radiation therapy
   3. Mesenteric ischemia
5. Trauma (particularly to the duodenum)
6. 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