Ischemic Colitis

 Emboli to SMA from cardiac sources most commonly

image Affects right colon ± small bowel

image CT findings often subtle (ileus, lack of mucosal enhancement, no wall thickening acutely)

• Mesenteric venous thrombosis
image Thrombosis or filling defect in SMV

image Marked submucosal edema of affected colon (right > left) ± small bowel

image Marked infiltration of mesentery ± ascites

• Hypoperfusion ischemia
image Elderly, cardiac patients; recent hypotensive episode

image Affects “watershed” areas of colon (splenic flexure and descending colon > sigmoid)

image Rectum is rarely affected by ischemic colitis


• Diverticulitis

• Infectious (including Clostridium difficile) colitis

• Granulomatous colitis (Crohn disease)


• Hypoperfusion: Predisposing factors
image Hypotensive episodes: Hemorrhagic, cardiogenic, or septic shock

image CHF, arrhythmia, drugs (e.g., digitalis), trauma


• Major predisposing cause in elderly: Nonocclusive vascular disease (hypoperfusion)
image Most common cause of colitis in elderly, often self-limiting

• Presentation: Bloody diarrhea, hypotension

(Left) Graphic shows luminal narrowing and wall thickening image near the splenic flexure, a “watershed” area between the vascular distribution of the SMA and IMA.

(Right) This 89-year-old man had pain and bloody diarrhea several hours after a hip arthroplasty procedure. Coronal reformatted CECT shows wall thickening and mucosal and mesenteric hyperemia affecting the descending colon image. Incidental renal allograft noted image.

(Left) Axial CECT in the same case shows submucosal edema and luminal narrowing of the descending colon image. The SMA and SMV are patent.

(Right) Another CT section in this patient shows wall thickening and pericolonic stranding of the descending colon image, whereas the remaining colon is normal. The rectum (not shown) was normal. These are classic clinical and CT features of ischemic colitis due to a hypotensive episode in an elderly patient.



• Compromise of mesenteric blood supply leading to colonic injury


General Features

• Best diagnostic clue
image Symmetric, long segmental colonic wall thickening on CT

image Pneumatosis, mesenteric venous gas; more definitive but less common findings

• Location
image Watershed segments of colon

Radiographic Findings

• Radiography
image Supine abdominal films
– Normal or nonspecific ileus

– “Thumbprinting” (submucosal edema or hemorrhage)

– Luminal narrowing or transverse ridging (spasm)

Fluoroscopic Findings

• Barium enema
image Hallmark: Serial change on studies performed over days, weeks, or months

image “Thumbprinting”
– Usually within 24 hours after onset

– Thickened, nodular transverse folds (submucosal edema or hemorrhage)

– Most consistent and characteristic finding (75% of cases)

image Ulceration: Mucosal sloughing
– Usually 1-3 weeks after onset

– Longitudinal or discrete, superficial or deep, small or large collections of barium

image Stricture: 12% of cases heal with stricture formation

image Intramural barium: Rare, due to sloughing of necrotic mucosa

CT Findings

image Circumferential, symmetric wall thickening ± “thumbprinting”
– Hypoattenuation of bowel wall: Submucosal or diffuse edema

– Hyperattenuation of bowel wall: Submucosal hemorrhage

image Luminal narrowing or dilatation, and air-fluid levels

image Pneumatosis: intramural gas in circumferential or band-like collections

image Gas in mesenteric and portal veins
– Tends to collect in periphery of liver (unlike biliary gas)

image Findings vary by acuity, etiology, and severity

image Acute arterial thromboembolic
– Emboli to SMA from cardiac sources most commonly
image e.g., prosthetic cardiac valves, prior myocardial infarction, atrial fibrillation

image Symptoms are more likely to be acute and severe

– Occlusion or filling defect in lumen of superior mesenteric artery (SMA)

– Affects right side of colon ± small bowel

– CT findings often subtle (ileus, lack of mucosal enhancement)
image No bowel wall edema or mesenteric infiltration until reperfusion occurs

image Pneumatosis ± portal venous gas: Late findings of frank infarction

image Mesenteric venous thrombosis
– Often in hypercoagulable patients

– Thrombosis or filling defect in SMV

– Results in marked submucosal edema of affected colon (right > left) ± small bowel

– Marked infiltration of mesentery ± ascites

– Mucosal enhancement is often normal or increased

– Onset of symptoms more likely to be subacute and less severe

Nov 16, 2016 | Posted by in GASTROINTESTINAL IMAGING | Comments Off on Ischemic Colitis

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