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Toxic Megacolon

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Toxic Megacolon, Toxic Colon Dilation

  • See Also
  1. Inflammatory Bowel Disease
  2. Bowel Obstruction
  • Definitions
  1. Toxic Megacolon
    1. Rare, life threatening, nonobstructive colon dilation, typically associated with systemic toxicity
  • Causes
  1. Ischemic Bowel
  2. Inflammatory Bowel Disease
    1. Ulcerative Colitis (10% of flares)
    2. Crohn Disease (2.3% of flares)
  3. Infectious Diarrhea
    1. Clostridioides difficile
    2. Salmonella
    3. Shigella
    4. Campylobacter jejuni
    5. Enterohemorrhagic Escherichia coli 0157
    6. Entamoeba histolytica (rare)
    7. Cytomegalovirus (CMV)
      1. CMV (esp. disseminated) is the most common cause of Toxic Megacolon in HIV and AIDS patients
  • Risk Factors
  1. Hypokalemia
  2. Bowel antimotility agents including Opioids and Anticholinergic Medications
  3. Barium Enema
  4. Colonoscopy preparation
  • Symptoms
  1. Fever and chills
  2. Abdominal Pain
  3. Diarrhea
    1. In contrast, obstipation (complete Constipation) is associated with a worse prognosis
  • Signs
  1. Abdominal tenderness
  2. Abdominal Distention
  3. Signs of Dehydration and systemic toxicity may be present (e.g. Sinus Tachycardia)
  • Differential Diagnosis
  1. Hirschprung Disease
  2. Large Bowel Obstruction
  3. Colonic pseudo-obstruction (Ogilvie Syndrome) or other acquired Megacolon
  4. Gastrointestinal dysmotility
  • Labs
  1. Complete Blood Count
  2. Comprehensive metabolic panel
  3. Inflammatory markers (e.g. C-RP, ESR)
  • Imaging
  1. Abdominal XRay
    1. Dilation >6 cm of the transverse colon or ascending colon
  2. Abdominal CT
    1. Colon wall thickening and submucosal edema
    2. Pericolic stranding
    3. Abnormal haustra pattern
    4. Accordion Sign (thick submucosal folds with overlying bands of alternating intensity)
    5. Target Sign (submucosal edema and mucosal hyperemia)
  • Diagnosis
  • Jalan Criteria
  1. Transverse Colon diameter > 6 cm AND
  2. At least 3 of the following AND
    1. Fever > 101.5 F (38.6 C)
    2. Heart Rate >120 beats/min
    3. White Blood Cell Count > 10.5k/mm3
    4. Anemia
  3. At least 1 of the following
    1. Dehydration
    2. Altered Mental Status
    3. Hypotension
    4. Electrolyte abnormality
  • Management
  1. Supportive Care
    1. Intravenous Fluids
    2. Correct Electrolyte abnormalities
    3. Withdrawal all medications affecting bowel motility
    4. Bowel rest (keep NPO)
    5. Consider bowel decompression with Nasogastric Tube and rectal tube
  2. Antimicrobials (due to high risk of associated perforation)
    1. Empiric Antibiotics coverage for bowel flora
    2. Screen and treat for Clostridioides difficile
    3. Treat suspected disseminated CMV with gancyclovir
  3. Inflammatory Bowel Disease (esp. Ulcerative Colitis)
    1. Methylprednisolone 60 mg daily for 5 days OR
    2. Hydrocortisone 100 mg every 6 hours
  4. Consult general surgery early in course
    1. Mixed outcomes for early surgical intervention versus medical management
      1. Younger patients may have better outcomes wiith early surgical intervention
      2. D'Amico (2005) Digestion 72(2-3): 146-9 [PubMed]
    2. Indications for surgery
      1. Bowel perforation
      2. Gastrointestinal Hemorrhage
      3. Clinical deterioration
    3. Procedures
      1. Subtotal colectomy and ileostomy (with Hartmann pouch, sigmoidostomy or rectostomy)
  • Complications
  1. Bowel perforation
  2. Peritonitis
  3. Abdominal Compartment Syndrome
  • Prognosis
  1. Mortality is as high as 19% (esp. with bowel perforation)
  2. Mortality rates in Inflammatory Bowel Disease is as low as 0-2% with early management
  • Resources
  1. Skomorochow and Pico (2022) Toxic Megacolon, StatPearls,Treasure Island
    1. https://www.ncbi.nlm.nih.gov/books/NBK547679/
  • References
  1. Kleinmann (2023) Crit Dis Emerg Med 37(2): 22-9
  2. Jalan (1968) Gastroenterology 57(1): 68-82 [PubMed]