Infectious Colitis

 Mucosal hyperenhancement, marked submucosal edema, ascites


image Multiple air-fluid levels, inflamed pericolonic fat


• Ultrasound findings
image Symmetric wall thickening and submucosal echogenicity

image Increased mural flow on color Doppler

• Fluoroscopic findings
image Used less frequently than before; now supplanted by CT, US, and endoscopy

• Clostridium difficile, Campylobacter, Escherichia coli, CMV
image Accordion sign: Alternating bands of enhancing mucosa and submucosal edema with compressed lumen

• May progress to hemorrhagic necrosis and perforation; toxic megacolon




TOP DIFFERENTIAL DIAGNOSES




• Ulcerative colitis
image Wall thickening is generally less prominent with UC

• Granulomatous colitis (Crohn disease)

• Ischemic colitis
image Usually located in watershed areas, rarely pancolitis

image Rectum is rarely affected by ischemic colitis


CLINICAL ISSUES




• C. difficile colitis occurs mostly in institutionalized patients or those on antibiotic, chemotherapy, or immunosuppressive medication

• Acute infectious diarrhea is most often foodborne or waterborne disease

• Most common bacterial causes of infectious colitis in USA
image C. difficile, Salmonella, Campylobacter, and E. coli

• Symptoms: Watery or bloody diarrhea, fever
image Painful abdominal cramps and tenderness

image Usually acute onset, except TB (chronic)

• Diagnosis: Stool cultures, blood cultures, endoscopic biopsy, serology studies

• Often self-limited or responsive to antimicrobial therapy in previously healthy patients

image
(Left) Graphic illustration demonstrates pancolitis with marked mural thickening and multiple elevated yellow-white plaques, or pseudomembranes, typical for Clostridium difficile colitis


image
(Right) Axial CECT in a 62-year-old man who presented with diarrhea and dehydration demonstrates a classic case of pseudomembranous (C. difficile) colitis. Note the severe bowel wall thickening throughout the entire colon image, and ascites. C. difficile colitis typically presents as a pancolitis, as in this example.

image
(Left) A 71-year-old woman had a history of recent antibiotic use for cellulitis and presented with nausea, vomiting, and diarrhea. Axial CT shows moderate diffuse bowel wall thickening image and hyperemia of the entire colon and rectum.


image
(Right) Coronal CECT in the same patient again illustrates moderate diffuse bowel wall thickening image of the entire colon. C. difficile (pseudomembranous) colitis was confirmed.


TERMINOLOGY


Definitions




• Colonic inflammation due to bacterial, viral, fungal, or parasitic infections

• Pseudomembranous colitis: Descriptive term usually applied to Clostridium difficile colitis


IMAGING


General Features




• Best diagnostic clue
image Usually pancolitis, including rectum

• Location
image Dependent on etiology
– C. difficile: Segmental or pancolitis
image Entire colon usually involved; distal SB uncommonly

– Campylobacteriosis: Pancolitis ± small bowel

– Escherichia  coli (O157:H7): Pancolitis

– Cytomegalovirus (CMV): Distal ileum and right colon or pancolitis

– Yersinia enterocolitis: Predominantly right colon, occasionally left; invariably in terminal ileum
image RLQ clusters of enlarged nodes

– Typhoid fever (salmonellosis): Cecum or right colon, invariably in ileum

– Shigellosis: Predominantly in left colon

– Tuberculosis: Right and proximal transverse colon, involves ileum

– Actinomycosis: Rectosigmoid colon (intrauterine devices), ileocecal region (appendectomy)

– Gonorrhea, chlamydia, herpes, syphilis: Rectosigmoid colon

– Histoplasmosis: Ileocecal region

– Mucormycosis: Right colon

– Anisakiasis: Occasionally in right colon, rarely in transverse colon

– Amebiasis: Right colon ±  terminal ileum

– Schistosomiasis: Left or sigmoid colon


Fluoroscopic Findings




• Contrast enema
image Used less frequently than before; now supplanted by CT, US, and endoscopy

image Narrowed lumen, haustral thickening (edema/spasm)

image Colonic wall, ulceration → mucosal irregularity, superficial or deep “collar-button” ulcers

image Discrete punctate, aphthous, or large oval ulcers, may simulate Crohn disease

image Small nodules or inflammatory polyps ± diffuse mucosal granularity (may simulate ulcerative colitis)

image Possible extrinsic mass with inflammatory changes → distortion, short strictures (may simulate carcinoma)

image Thumbprinting, may simulate ischemic colitis

image May show fistulas or sinus tracts

image Typhoid fever: Ileal fold thickening and ulceration

image Shigellosis: Mucosal granularity of rectum

image Tuberculosis
– Oval/circumferential transverse ulcers; loss of demarcation between distorted terminal ileum and ascending colon

– Fleischner sign: Right-angle intersection between ileum and cecum, marked ileocecal valve hypertrophy

– Marked mural thickening > Crohn disease

– “Apple core” colonic stricture, indistinguishable from carcinoma

image Histoplasmosis: Rectal polyps, pericecal masses, may simulate appendicitis

image Mucormycosis: Polypoid mass

image Amebiasis
– Skip lesions, may simulate granulomatous colitis

– Ameboma: Marked granulation in short segments of right colon

– Discrete ulcers appearing as marginal effects or granularity with barium flecks

image Schistosomiasis: Inflammatory polyps, granulation response to eggs deposited in bowel wall


CT Findings




• C. difficile, Campylobacter, E. coli, CMV
image Mucosal hyperenhancement, marked submucosal edema, ascites

image Accordion sign: Alternating bands of enhancing mucosa and submucosal edema, with compressed lumen

image Multiple air-fluid levels, infiltrated pericolonic fat

image Deep ulcers and marked wall thickening
– May progress to hemorrhagic necrosis and perforation

– Toxic megacolon

• TB: Marked low-density enlargement of mesenteric lymph nodes
image Enterocolitis is often due to ingestion of Mycobacterium bovis

image Lungs may not be involved

• Histoplasmosis: Mesenteric adenopathy, hepatosplenomegaly ± calcifications

• Schistosomiasis: Changes in mesenteric or hemorrhoidal vein
image ± calcification of bowel wall or liver

image Bladder wall thickening and calcification

• Salmonellosis: May show small bowel thickening and effacement

• Actinomycosis: Large inflammatory masses

• Mucormycosis: Sinus, lung, and central nervous system changes

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

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