What is the role of colonoscopy in the diagnosis of amebiasis?

Updated: Jul 19, 2019
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Rectosigmoidoscopy and colonoscopy with biopsy or scraping at the margin of a colonic mucosal ulcer provide valuable materials for diagnostic information in intestinal amebiasis. Tissue can be sent for microscopic evaluation, culture, and PCR assay, where available.

Indications for endoscopy in suspected intestinal amebiasis include the following:

  • Stool examination findings are negative, but serum antibody test findings are positive

  • Stool examination findings are negative, but immediate diagnosis is required

  • Stool examination and antibody test results are negative, but amebiasis is strongly suspected

  • Evaluation of chronic intestinal syndromes or mass lesions is desired

Fulminant colitis is a relative contraindication to colonoscopy, because it increases the risk of intestinal perforation.

On endoscopic examination, small mucosal ulcers covered with yellowish exudates are observed. The mucosal lining between the ulcers appears normal. The mucosa resembles that seen in inflammatory bowel disease (IBD). Biopsy results and a scraping of ulcer edge may reveal trophozoites. Ameboma (a carcinomalike annular lesion) can also be seen, usually in the cecum and ascending colon. [4, 64]

Rectosigmoidoscopy and colonoscopy should be considered before steroids are used in patients with suspected IBD. In a multivariate analysis, the best combination of findings for predicting amebic colitis was the combination of cecal lesions, multiple lesions, and exudates. [65]

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