Thickening of small bowel folds.

W1 Thickening of small bowel folds (> 3 mm) can be caused by any process that increases the volume of fluid or cells in the submucosal or mucosal region (Table 1). The critical diagnostic observation is whether the general pattern of the thickening is regular or irregular. Regular thickening of small bowel folds, which are perpendicular to the bowel lumen and parallel to neighboring folds, is usually caused by fluid, generally hemorrhage or edema (Fig. 1). Irregular thickening of small bowel folds is produced by an extensive group of diseases that infiltrate the bowel wall with deposition of cells or other amorphous material. In these conditions, the folds are distorted, not perpendicular to the lumen, and are angled with respect to neighboring folds (Fig. 2). Thickening of Small Bowel Folds Res idents ’ Sect ion • Pat tern of the Month