Toxic megacolon

Background

• Colonic Dilation ≥6cm
• Therapy: Fluids, Electrolyte Repletion, Steroids, Antibiotics, Surgical Consultation
• AVOID anticholingerics, anti-motility agents, opioids

Causes

• Most commonly IBD (Ulcerative Colitis >>> Crohn's disease)
• Bacterial (Salmonella, Shigella, Campylobacter, C. Diff, Yersinia, E. Coli)
• Viral (CMV, Rotavirus)
• Fungal/Protozoa (Aspergillus, Entamoeba, Cryptosporidium)
• Drugs (Anti-motility agents, anticholinergics, opioids)
• Less Common Causes (Ischemic Colitis, Collagenous Colitis, Obstructive Colorectal Cancer, Colonic Lymphoma, Kaposi's Sarcoma, Chemotherapy)
• Pediatric Population (Hirschsprung's Disease, Hemolytic Uremic Syndrome)
• HIV/AIDS Population (CMV, C. Diff)

Clinical Features

• Abdominal Pain ± Distention
• Fever
• Tachycardia
• Diarrhea, ± Bloody
• Hypotension
• Altered Mental Status (AMS)
• Bowel perforation
  • Peritonitis
  • Septicemia

Differential Diagnosis

• Small bowel obstruction
• Large bowel obstruction
  • Volvulus, Neoplastic Disease, Paralytic ileus, Pseudo-obstruction
• Colitis
  • Infectious, Inflammatory, Ischemic

Evaluation

Toxic megacolon on KUB

• Plain abdominal radiographs:
  • Colonic Dilation ≥6 cm diameter
  • Loss of haustra, "thumb-printing" (bowel edema)
  • Air-fluid levels
• Abdominal Ultrasound:
  • Thin colonic walls with loss of haustra coli
  • Diameter ≥6cm with gaseous content
• Labs:
  • Leukocytosis
  • Electrolyte derangements: Hypokalemia, Hypomagnesemia
  • Elevated ESR/CRP
  • Anemia
  • Hypoalbuminemia

Management

• Fluid resuscitation
• IV corticosteroids
  • Hydrocortisone IV 100mg q6h
• Triple Antibiotic Therapy
  • Ampicillin 2 g IV q6h PLUS Metronidazole 500mg IV q6h PLUS Gentamicin 7mg/kg q24h or Ciprofloxacin 400mg IV q12h OR
  • Imipenem 500mg IV q6h
• Electrolyte repletion
  • Aggressively treat hypokalemia and hypomagnesemia because these can exacerbate dilation
• Emergent Surgical Consultation

• Obtain blood cultures, stool cultures, C. Diff Toxin
• If known cause is C. Diff treat with Vancomycin or Metronidazole
• If known cause is CMV can add Ganciclovir

• Avoid
  • Anticholinergics, anti-motility agents, opioids which can worsen dilation
  • Sulfasalazine or 5-aminosalicylate (5-ASA) unhelpful
  • Nasogastric (NG) Tube NOT effective in reducing colonic distention

Disposition

• Admit

See Also

• Crohn's disease
• Ulcerative Colitis