 A small bowel follow-through may suggest the diagnosis of Crohn's disease and is useful when the disease involves only the small intestine.Because colonoscopy and gastroscopy allow direct visualization of only the terminal ileum and beginning of the duodenum, they cannot be used to evaluate the remainder of the small intestine.As a result, a barium follow-through X-ray, wherein barium sulfate suspension is ingested and fluoroscopic images of the bowel are taken over time, is useful for looking for inflammation and narrowing of the small bowel.