Updated: 7/17/2019

Large Bowel Obstruction

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https://upload.medbullets.com/topic/120185/images/lbo.jpg
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Snapshot
  • A 65-year-old man presents to the emergency room for increased abdominal pain and distention. He has a history of diverticulosis and chronic constipation. He last had a bowel movement 1 week ago and has not had any flatus in the past day. He reports 2 episodes of vomiting at home. On physical exam, his abdomen is distended and there is diffuse tenderness to palpation. A CT of his abdomen and pelvis shows dilated loops of bowel and a suspicious mass at the transition point. The surgery team is consulted and he is prepped for surgical intervention.
Introduction
  • Overview
    • large bowel obstruction, or LBO, is a surgical emergency and requires intervention
      • obstruction may be partial or complete
      • complete obstructions require immediate surgical intervention
  • Epidemiology
    • demographics
      • elderly patients
    • etiology
      • volvulus
      • intussusception
      • colonic mass/malignancy
      • diverticular disease
      • fecal impaction
      • stricture
      • incarcerated hernia
    • risk factors
      • chronic constipation
  • Pathogenesis
    • mechanism
      • mechanical obstruction in the large bowel causes bowel dilatation above the point of obstruction
        • causes bowel edema and ischemia
        • causes electrolyte abnormalities
  • Prognosis
    • prognostic variable
      • if treated early, mortality for LBO is low
      • if there is bowel ischemia or perforation, mortality is higher
Presentation
  • History
    • chronic constipation
    • lack of flatus
      • indicates complete obstruction
      • some passage of flatus or stool
        • indicates partial obstruction
  • Symptoms
    • crampy abdominal pain
    • nausea and vomiting
    • bloating
  • Physical exam
    • inspection
      • abdominal distention
    • motion
      • tenderness to palpation
      • abdominal rigidity
      • quiet or absent bowel sounds
    • provocative tests
      • digital rectal exam
        • may reveal hard stool in the rectal vault
Imaging
  • Abdominal radiographs 
    • indications
      • all patients
      • screen for free air under the diaphragm
    • views
      • flat
      • upright
    • findings
      • dilated bowel 
  • Contrast radiography with enema
    • indication
      • if CT findings are equivocal and volvulus is suspected
    • findings
      • “bird’s beak” appearance
  • Computed tomography (CT) of abdomen and pelvis with contrast
    • indications
      • imaging of choice for diagnosis of LBO
      • distinguishes between a partial or complete obstruction
    • findings
      • mechanical obstruction identified
      • dilated loops of bowel
    • contrast agent
      • gastrografin should be used if bowel perforation is suspected
Studies
  • Serum labs
    • basic metabolic panel
      • to correct any electrolyte abnormalities
    • lactate
      • to evaluate for bowel ischemia
    • complete blood cell count
      • white blood cells are only mildly elevated
Differential
  • Small bowel obstruction
    • key distinguishing factor
      • dilated loops of small bowel seen on imaging, rather than dilated loops of large bowel
  • Ogilvie syndrome
    • key distinguishing factor
      • no mechanical lesion on CT imaging that can cause the obstruction
Treatment
  • Lifestyle
    • modified diet
      • indications
        • for patients with history of obstruction
      • modalities
        • high-fiber diet
        • stool softeners
  • Medical
    • observation and bowel rest
      • indications
        • mild symptoms without vomiting
      • modalities
        • intravenous fluids
        • correct electrolyte abnormalities
    • nasogastric decompression and bowel rest
      • indications
        • abdominal distention
        • vomiting
  • Surgical
    • exploratory laparotomy
      • indications
        • complete LBO
        • bowel ischemia
        • volvulus
Complications
  • Ischemic colitis
  • Bowel perforation
 

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