50 INFLAMMATORY BOWEL DISEASE
Anthony J. LaPorta M.D., Gilbert Hermann M.D.

1. What two clinical entities encompass the diagnosis of inflammatory bowel disease?

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Crohn’s disease and ulcerative colitis (acute or chronic).

2. Although the two diseases often overlap, they usually can be distinguished by clinical criteria. What are the major clinical differences?

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Rectal bleeding is unusual in Crohn’s disease but common in chronic ulcerative colitis. An abdominal mass and anal complications (fissure, fistula) are more common in Crohn’s disease.

3. What are the major radiologic differences between the two diseases?

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Terminal ileal involvement, skip areas, internal fistulas, and “thumb printing” are rare or absent in chronic ulcerative colitis but common in Crohn’s disease.

4. What are the major histologic differences?

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Granulomas in the intestinal wall and adjacent lymph nodes are absent in ulcerative colitis but occur in 60% of patients with Crohn’s disease. The inflammatory process in Crohn’s disease involves the entire bowel wall. In ulcerative colitis, the inflammation usually is limited to the mucosa and submucosa.

5. Although Crohn’s disease may affect the gastrointestinal (GI) tract from the pharynx to the anus, what are the most common clinical patterns of GI involvement?

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Small bowel only: 28%; both ileum and colon (ileocolitis): 41%; and colon only: 27%. Crohn’s involvement of the colon is also called Crohn’s colitis or granulomatous colitis.

6. Crohn’s colitis and ulcerative colitis are often difficult to distinguish clinically. What are the major differences at colonoscopy?

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Crohn’s disease is focal and predominantly right sided. The mucosa has a cobblestone appearance with transverse ulcerations in affected areas. Biopsies reveal transmural disease with possible focal granulomas. On colonoscopy, chronic ulcerative colitis may appear as a diffuse disease. However, if only a portion of the colon is involved, it is on the left side and almost always involves the rectum. Pathologic changes involve the mucosa and submucosa.

7. What are the major indications for surgery in Crohn’s disease?

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It depends on the site of involvement. Enterocutaneous or enteroenteral fistulas (controversial), abscess, and intestinal obstruction are the most common surgical indications for small intestinal and ileocolic types. Perianal disease, medical failure, ileocolic fistulas, and abscess formation are the most common indicators for surgery in Crohn’s colitis.

8. What are the major indications for surgery in ulcerative colitis?

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Medical intractability (including failure to thrive in children, diarrhea, weight loss, and abdominal pain), toxic megacolon with or without perforation, and concern about the development of colonic cancer (controversial, but real).

KEY POINTS: DIFFERENCES BETWEEN CROHN’S DISEASE AND ULCERATIVE COLITIS

1. Rectal bleeding is uncommon in Crohn’s disease but common in chronic ulcerative colitis.
2. Terminal ileal involvement, skip areas, internal fistulas, and “thumb printing” are common in Crohn’s disease but rare or absent in chronic ulcerative colitis.
3. In ulcerative colitis, the inflammation is usually limited to the mucosa and submucosa, whereas in Crohn’s disease it involves the entire bowel wall.

9. What is the surgical treatment of ulcerative colitis?

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Total colectomy with ileoanal pouch anastomosis is the standard. A total colectomy with a Brooke ileostomy was the classic surgical approach and is still applicable in some situations. A Kock (continent) pouch can be used for younger (age < 55 years) patients who do not wish to wear an ileostomy bag or who have lost their ileoanal pouch. Ileorectal anastomosis has been advocated by some (controversial), but this leaves disease behind.

10. What are the surgical procedures for the complications of Crohn’s disease?

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Complications requiring surgery are usually corrected by removing all areas of bowel involved in the complication. Strictureplasty as opposed to resection is now preferred in selected cases of small bowel obstruction. When resection is necessary, grossly clear margins are satisfactory. Skip areas should be preserved unless they are directly adjacent to resected intestine.

11. What should the patient be told about the possibility of recurrence after surgery?

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With chronic ulcerative colitis, surgery is definitive and curative. With Crohn’s disease, however, the aim of surgery is to treat the complications (i.e., obstruction and sepsis). Recurrence of Crohn’s disease can be expected in a high percentage of cases if the patient is followed long enough. Small bowel recurrence after total colectomy for Crohn’s colitis does occur.

12. How do you evaluate the placement of a stoma?

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The location of a stoma is a major factor in patient morbidity. Placement is optimal at the summit of the infraumbilical bulge within the rectus muscle. This is usually within a triangle formed by lines between the umbilicus to the anterior superior iliac spine, umbilicus to the pubis, and the inguinal ligament. All scars and creases should be avoided.

13. Does Crohn’s disease have a genetic basis?

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The patients described by Crohn et al. in the original article were a 14-year-old boy and his 32-year-old sister. Genetic studies have identified two loci, IBD1 and IBD2 on chromosomes 16 and 12, respectively, that are linked to inflammatory bowel disease. New data suggest that these mutations affect the innate bacterial reaction to lipopolysaccharides, leading to an exaggerated immune response, causing the tissue damage in Crohn’s disease. Similar studies also have links to chromosomes 14q and 6p.

14. What is the difference between an enteroclysis and a small bowel follow-through?

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Enteroclysis is a procedure performed by a radiologist with a catheter placed at the duodenal-jejunal junction. Because the rate of barium entering the intestine and thus distention of the intestine can be controlled, this study provides a superior demonstration of the luminal contour, valvulae conniventes, and mucosal surface. Thus, it is superior to the small bowel follow-through for the evaluation of short obstructing lesions but is a technically more demanding procedure for the radiologist and the patient.

15. What is a Brooke ileostomy?

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The Brooke ileostomy is the “rosebud” or full-thickness ileostomy folded over on itself for approximately 1 cm above the skin. This prevents the erosion of the skin and high-output serositis that is common with an ostomy that is flush with the skin.

16. What is pouchitis, and which patients are likely to have it?

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Pouchitis is an inflammation of indeterminate origin, possibly related to bacterial overgrowth, that occurs in the ileal pouch after ileal-pouch anal anastomosis. This complication is common (25%) when this procedure is performed for ulcerative colitis, but it is rare when this same procedure is performed for familial polyposis. Patients with pouchitis are effectively treated with metronidazole, ciprofloxacin, or 5-amino salicylic acid. They rarely require ileal diversion or pouch excision.