LAUSR

A particular imaging feature that helps in the differentiation between UC and CD is the pattern of bowel wall involvement: the first tends to be limited to the superficial layers in a continuous fashion, while the latter tends to present transmural involvement, interweaving healthy mucosa and inflamed areas [1]. Hypertrophy of muscularis mucosae secondary to continuous regeneration promotes loss of haustration and reduction of the usual colon caliber. Fat proliferation due to chronic inflammation also can contribute to this pattern of continuous colonic involvement [2]. Classically described on barium enema exams (Fig. 1) almost a century ago [3], this appearance of smooth, ahaustral contour was compared to a water or gas pipe (Figs. 1, 2), and later also applied to computed tomography enterography and Magnetic Resonance enterography (Figs. 3, 4). Despite its correlation with UC, the ‘‘Lead Pipe’’ can also be found in other forms of inflammatory bowel diseases, and even in CD. It occasionally accompanies infectious colitides such as tuberculosis and amebiasis, and can be a sign of cathartic colon. The lead pipe sign, while not is not disease-specific, provides an indicator of chronic colonic pathology [1–4].