A 22-year-old man with inflammatory bowel disease is noted to have a “string sign” in the ileal area on barium enema. In which of the following conditions is this sign most often seen?
**Core Concept**
The "string sign" refers to the radiographic appearance of a narrow, elongated, and rigid segment of bowel on barium studies, typically seen in conditions that cause chronic inflammation and fibrosis of the intestinal wall.
**Why the Correct Answer is Right**
In the context of inflammatory bowel disease (IBD), the "string sign" is most commonly associated with chronic inflammation and fibrosis of the terminal ileum, leading to narrowing of the lumen. This is often seen in Crohn's disease, where the inflammation can cause transmural damage and fibrosis, resulting in a characteristic "string sign" on barium studies. The fibrosis and chronic inflammation lead to the formation of a rigid and narrowed segment of bowel, which is visualized as a "string" on barium enema.
**Why Each Wrong Option is Incorrect**
**Option A:** **Ulcerative Colitis** - While ulcerative colitis is a form of IBD, it primarily affects the colon and rectum, and is less likely to cause a "string sign" in the ileal area.
**Option B:** **Diverticulitis** - Diverticulitis is a condition characterized by inflammation of diverticula in the bowel wall, but it is not typically associated with a "string sign" on barium studies.
**Option C:** **Intussusception** - Intussusception is a condition where one segment of bowel telescopes into another, but it is not typically characterized by a "string sign" on barium studies.
**Clinical Pearl / High-Yield Fact**
In patients with IBD, the "string sign" on barium studies is a classic radiographic finding that suggests chronic inflammation and fibrosis of the terminal ileum, which is often associated with Crohn's disease.
**Correct Answer:** C. Crohn's disease.