Ischemic Colitis

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 19/07/2015

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 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

TOP DIFFERENTIAL DIAGNOSES

• Diverticulitis
• Infectious (including Clostridium difficile) colitis
• Granulomatous colitis (Crohn disease)

PATHOLOGY

• Hypoperfusion: Predisposing factors

image Hypotensive episodes: Hemorrhagic, cardiogenic, or septic shock
image CHF, arrhythmia, drugs (e.g., digitalis), trauma

CLINICAL ISSUES

• Major predisposing cause in elderly: Nonocclusive vascular disease (hypoperfusion)

image Most common cause of colitis in elderly, often self-limiting
• Presentation: Bloody diarrhea, hypotension
image
(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.

image
(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.
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.

image
(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.

TERMINOLOGY

Definitions

• Compromise of mesenteric blood supply leading to colonic injury

IMAGING

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

• NECT

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)
• CECT

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
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