- Common in elderly
- 90% cases in patients >60 years old
- Sudden onset abdominal pain, rectal bleeding
Etiology
- Mesenteric occlusion: arterial or venous
- Mechanical: strangulation or raised intracolonic pressure proximal to an obstruction
- Low-flow states
- Young patients: hypercoagulable states, vasculitis, long-distance running, cocaine use
Spectrum
- Splenic flexure most commons site (watershed zone between SMA-IMA)
- Right colon affected in low-flow states
- Mucosa – most susceptible, but can repair
- Submucosa, muscle layer – necrosis leads to fibrosis and stricture formation
- Transmural necrosis / bowel infarction: life threatening, requires immediate surgery
Imaging
- Plain radiograph: narrowing, thumbprinting. Helps to exclude toxic megacolon, free perforation, intramural or portal venous gas
- USG: thickened wall with stratification
- CT: wall thickening worse with venous occlusion. Low-attenuation target sign due to submucosal edema. Pneumatosis or portomesenteric gas suggests transmural necrosis. Look for large vessel occlusion.
- Features not specific for ischemia but overlaps with infection
- Wall thickness does not correlate with extent of ischemia
- Mesenteric fat stranding
- Free fluid
Read more
Thoeni, Ruedi F., and John P. Cello. “CT imaging of colitis.” Radiology 240.3 (2006): 623-638.