Crohn's disease affects approximately 780,000 Americans and is characterised by transmural, discontinuous inflammation that can involve any segment of the GI tract, most commonly the terminal ileum and colon. Unlike ulcerative colitis, which is limited to the mucosa, Crohn's disease penetrates the full thickness of the bowel wall, causing complications including strictures (narrowing), fistulae (abnormal connections), and abscesses. The therapeutic armamentarium has expanded dramatically with biologic therapies. Anti-TNF agents (infliximab, adalimumab), vedolizumab (gut-selective), ustekinumab (anti-IL-12/23), and risankizumab (anti-IL-23) all have proven efficacy. Treatment goals have shifted from symptom control to mucosal and transmural healing — deep remission — which reduces the risk of surgery and disease complications.
