Which findings on ultrasonography are characteristic of ulcerative colitis (UC)?

Updated: Apr 23, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Most bowel pathologies cause thickening of the bowel wall. On bowel examination, a target sign is usually seen. With this sign, a hypoechoic wall surrounds the echogenic mucosa, intraluminal mucous, air, and other bowel contents. This target may be round or oval (pseudo-kidney sign).

Under normal physiologic conditions, the hypoechoic bowel wall measures less than 4 mm. With few exceptions, this 4-mm rule may be applied to the whole of the bowel. Under pathologic conditions, the bowel wall thickens symmetrically in target fashion. It may be thickened asymmetrically when the echogenic lumen is displaced to one side on a true cross-section; this is the atypical target sign.

Most bowel pathology, whether inflammatory or neoplastic, may be inferred from the aforementioned signs. As with most imaging findings, these signs are nonspecific and suggest only a differential diagnosis. US findings of mural thickening of the bowel with a paucity of luminal content may be helpful in the detection of IBDs. However, the findings are nonspecific, and the differential diagnosis must be related to the specific segment of the bowel involved.

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