Normal Small Bowel Findings and Normal Variants of the Small Bowel

The lumen of the small bowel is ringed by circular mucosal folds, the so-called valvulae conniventes (Kerckring’s folds), which gradually decreased distally. The mucosal surface is characterized by fingerlike extensions, the villi. Lymphoid follicles are scattered throughout the small bowel but are found in highest concentrations in the distal ileum. These structures can be viewed by conventional endoscopy, capsule endoscopy, or device-assisted enteroscopy. The characteristics of the images among those modalities are different because of the different way of image-making. This chapter reviews the images of normal small bowel from the conventional endoscope, capsule endoscope, and device-assisted enteroscope as well as some artifacts and common normal variants that may be encountered during small bowel examinations.