medical condition characterized by inadequate blood supply to the large intestine leading to inflammation and injury of the colon

1. Ischemic Colitis

2. Clinical definition
Medical condition characterized by inadequate blood supply to the large intestine leading
to inflammation and injury of the colon.
Spectrum of disease from transient mucosal inflammation to gangrene.

3. Epidemiology
Demographics
more common in the elderly population
most common form of bowel ischemia
Risk factors
aortoiliac surgery/instrumentation
myocardial infarction
hemodialysis
hypercoagulable states (e.g., hereditary thrombophilia)

4. Pathogenesis
Ischemic colitis is the result of blood flow reduction to the colon and is particularly
prominent at the “watershed” areas of the colon where collateral blood flow is limited
the splenic flexure and rectosigmoid junction are particularly at risk for ischemia
Nonocclusive colonic ischemia
accounts for the mass majority of cases (95%)
examples include AMI, shock, systemic hypotension, Cardiopulmonary bypass, Strenous
prolonged exercise.

6. Pathogenesis
Occlusive colonic ischemia
◦ can be embolic (e.g., spontaneous or iatrogenic) or thrombotic secondary to
atherosclerotic disease.
◦ Mesenteric venous thrombosis
◦ Aortoiliac surgery
◦ Vasculitis
◦ Drugs - Cocaine
Colon receives less blood supply as compared to as compared to rest of GIT thus
vulnerable to hypoperfusion.

8. Pathogenesis
Distribution of ischemic changes
Most commonly Splenic flexure and descending colon.
After AAA repair and IMA Ligation - Usually involve sigmoid colon.
Embolic diseases – usually involve right colon.

11. Pathogenesis
Mechanism of Injury
Hypoxia causes detectable injury to superficial mucosa within one hour
Prolonged severe ischemia – necrosis of villous layer which Leads to transmural
infarction in 8 to 16 hrs
Reperfusion injury - mediated by release of oxygen free radicals and neutrophil
activation

12. Signs and Symptoms
Mild cramping abdominal pain commonly involving the left side with or without faecal
urgency
Rectal bleeding
Diarrhoea
Signs of peritonitis
Clinical context - post AAA repair

14. Ischemic Colitis Clinical stages
Hyperactive phase
Soon after initiating event, severe pain with frequent bloody, loose stools
Paralytic phase
Pain diminishes, more continuous, and diffuse
Abdomen more distended, tender, without BS
Shock phase (10 to 20%)
Massive fluid, protein, and electrolyte leakage through gangrenous mucosa
Severe, shock and metabolic acidosis, may develop
Rapid surgical intervention required

15. Diagnostic testing
diagnosis is often based on clinical presentation and confirmed via endoscopy
Physical exam
Laboratory
Stool cultures for suspected infectious cause
Increase serum lactate, LDH, CPK, or amylase
Metabolic acidosis
Elevated white count >20,000

16. Radiological imaging/Endoscopic studies
Plain abdominal x-ray
Contrast studies
Computed Tomography
May be normal initially
Thickening of bowel wall in segmental pattern and mesenteric stranding
Pneumatosis and gas in mesenteric veins in advanced stages
Endoscopy

19. Ischemic Colitis Colonoscopy
no evidence of peritonitis or perforation
Preferred to contrast enemas, more sensitive in detecting mucosal lesions
Segmental distribution, abrupt transition between injured and non injured mucosa, rectal
sparing, and rapid resolution on serial endoscopy
"single-stripe sign" - linear ulcer along longitudinal axis
Biopsies may show non-specific changes (mimicking Crohn's disease)

22. Ischemic Colitis Contrast studies
Thumbprinting most suggestive on double contrast
study seen early in disease In a small series of patients
with mucosal ischemia 75% +thumbprinting, 60%
longitudinal ulcers (source)

24. Invasive studies - angiography, laparoscopy (dx unclear or means to follow patient
postoperatively)
Angiography (rarely helpful)
Laparoscopy
Particularly in elderly with comorbid disease and may not tolerate laparotomy
"Second-look" to assess viability of remaining bowel
Only serosal gut visualization, which may appear normal in early stages; progressive
phase, dark peritoneal fluid, edematous bowel, or patchy hemorrhages, frank gangrene,
or perforation may be present
Magnetic Resonance Angiography, Duplex sonography hardly ever required for colonic
ischemia

25. Differential diagnosis
Infectious colitis - C. difficile, parasitic
Inflammatory bowel disease
Diverticulitis
Radiation enteritis
Solitary rectal ulcer syndrome
Colon carcinoma

26. Management
Nonocclusive ischemia
Supportive
IVF, bowel rest, empiric antibiotics (mod to severe cases)
NGT (ileus)
Hold meds that can promote ischemia
Optimize cardiac and pulmonary function
Laparotomy with resection
Clinical deterioration despite conservative therapy

28. Colonic infarction
Requires urgent surgical intervention
Bowel prep should not be given prior to surgery
Right-sided ischemia/necrosis
Right hemicolectomy with primary anastamosis
If perforation associated with peritonitis, resection with terminal ileostomy mucocutaneous fistula
Left-sided involvement
Proximal stoma and distal mucous fistula or Hartmann's procedure
Ostomy closure delayed 4 to 6 months
Fulminating type (rare)
Total colectomy with end-ileostomy

29. Prognosis
Most patients with non-occlusive ischemia improve within 1 or 2 days
A minority develop long-term complications
Segmental colitis or stricture
Approx. 15% develop severe gangrene
5-yr survival 70-86% those that survive surgical revascularization