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