Figure 3a. Enteroenteric and enterocolic fistulas. (a) Frontal radiograph from barium-enhanced small-bowel study in a 25-year-old man with Crohn disease shows multiple fistulous tracts extending from the terminal ileum (arrowheads), converging to a small mesenteric cavity (*), and communicating with the cecum and more proximal ileum (arrows). (b) Transverse contrast-enhanced CT scan in a 24-year-old man with Crohn disease shows irregular bowel wall thickening, mesenteric infiltration, and contrast agent-filled extraluminal tracts (arrows) centered in the ileocecal region. This complex enterocolic fistula involved distal ileum, cecum, ascending colon, and sigmoid colon.