Megacolon (Ogilvie’s Syndrome)

(Gastrointest Endosc 2002;56:789-92)

DEFINITION:

Ogilvie’s Syndrome (Acute Colonic Pseudo-obstruction): acute non-toxic megacolon without evidence of more distal colonic obstruction
- Usually dilation of cecum and/or right side of colon
Acute Toxic Megacolon: serious, life-threatening complication (usually late) of IBD or pseudomembranous colitis or Typhlitis or Ischemia
- Typhlitis: necrotizing of cecum in setting of neutropenia (usually seen in chemotherapy or immunosuppression)
  - Infection usually follows with ensuing necrosis, colonic dilation, perforation; Death 50%, typically due to perforation
Toxic vs. Nontoxic Megacolon See also IBD– Ulcerative Colitis (Chapter 3.04)

Clinical situation is best predictor of various cause of toxic and nontoxic acute megacolon
- Toxic Megacolon: usually involves entire colon in patients with UC
  - Two or more: HR >100/min, Temp >101.5°F (38.6°C), WBC >10,000, Hypoalbuminemia <3.0 gm/dl
- Thumbprinting on KUB suggest ischemia
Congenital: Hirschsprung’s: aganglionosis of rectum, beginning at dentate line and extending cephlad
- So the dilated appearing colon is normal & trying to accommodate, the distal portion that looks ‘normal’ is the problem (denervated)
Acquired megacolon: Idiopathic, DM, Amyloidsosis, Scleroderma, Parkinson’s, Muscular dystrophy, Chaga’s disease