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Crohn’s disease 

Crohn’s disease
Chapter:
Crohn’s disease
Author(s):

Miles Parkes

, and Tim Raine

DOI:
10.1093/med/9780198746690.003.0306
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date: 05 March 2021

Crohn’s disease is a common form of chronic inflammatory bowel disease. Typically involving one or more of the terminal ileum, colon, and perineum, it causes patchy transmural inflammation characterized microscopically by granulomata. Common complications include fibrotic strictures, fistulas, and abscesses. The initiating trigger is unknown, but an unregulated mucosal immune response to commensal bacteria drives the chronic inflammation. Variants in several genes involved in innate immunity are strongly associated, and smoking also increases the risk. Crohn’s disease confers significant morbidity but low mortality. Treatment of acute inflammatory disease is usually with corticosteroids or (occasionally) therapeutic diets, the latter particularly in children. For steroid dependence, frequent relapse, or objective evidence of uncontrolled mucosal inflammation, immunosuppression is indicated with immunomodulator or biological therapy or a combination of the two. First-line immunomodulators are azathioprine or 6-mercaptopurine, with methotrexate used as second-line therapy. Antitumour necrosis factor-α‎ (anti-TNFα‎) antibody therapy can induce rapid remission of resistant disease and has a key role in maintaining remission in such cases. Despite increased use of immunosuppressants, 70 to 80% of patients require surgery in the long term, most commonly for ileal stricturing. Timely, conservative surgery is the key, minimizing the length of small-bowel resected and using laparoscopic approaches where possible. For colonic disease requiring surgery, segmental colectomy or subtotal colectomy with ileorectal anastomosis are preferred, but significant rectal or perianal involvement may require proctocolectomy and ileostomy. Perianal Crohn’s disease is treated medically with antibiotics, azathioprine, and anti-TNF antibody therapy, and surgically with abscess drainage and placement of seton sutures through fistulas where possible. Some fistulas heal with intensive medical therapy. Others may warrant attempts at surgical repair if they produce unacceptable symptoms.

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