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P641 Does Ulcerative Colitis prevent the development of colonic diverticulosis?

G. Mantzaris*, E. Archavlis, A. Christidou, K. Papamichael, N. Kyriakos, P. Karatzas, X. Tzannetakou, S. Anastasiadis, I. Internos, L. Varytimiadis

Evangelismos Hospital, Gastroenterology Department, Athens, Greece

Background

Colonic diverticulosis (D) is common after 40 years of age in the western world. Advanced age, constipation, low-fiber diet, and connective tissue disorders are risk factors for D. A segmental colitis which shares some endoscopic and histologic features with IBD [Segmental Colitis Associated with Diverticulosis (SCAD)] has also been described in patients with diverticulosis. On the contrary, ulcerative colitis (UC) affects younger people and inflammation involves the rectosigmoid area in the vast majority of patients. Aim: To study the incidence of D in patients with UC

Methods

This was a prospective, single-center study. Between 2006 and 2013, 267 patients [141 males, mean age 36 years (range 17-75), median disease duration 7 years (range 0.6-34), 35 (25%) smokers], with UC[extensive (n=107), left sided (n=142) proctitis (n=18)] in clinical remission underwent colonoscopy to assess disease extent and/or epithelial dysplasia. 335 subjects, matched for age, gender, place of birth, inhabitance (rural or urban) and dietary habits who underwent colonoscopy for irritable bowel syndrome, iron deficiency, or colorectal cancer screening served as controls. The presence and distribution of diverticula was recorded. Exclusion criteria were known D, Crohn's disease or uninvestigated signs of complicated D (such as bleeding, bowel obstruction, diverticulitis, etc).

Results

Diverticula were detected only in 13/267 (4.9%) UC patients [7 with proctitis, and 6 with left-sided colitis (4 distal colitis)] but in 195/355 (55%) controls (p<0.0001). D in UC was detected in patients over 55 years of age, usually outside the area of distribution of UC. In the control group, diverticula were predominantly distributed in the left colon; 22/355 (6.2%) patients had SCAD and two of these 22 patients had rectal involvement. A significantly less proportion of UC patients were smokers.

Conclusion

In contrast to the general population, diverticula are rare in UC. Several factors may be accounted for this inverse association such as young age at UC onset, involvement of the left colon, non-smoking, and probably the production of pro-inflammatory cytokines (especially TNFa) which strengthen the enteric wall by inducing hyperplasia/hypertrophy of the muscle layers and changing the composition of connective tissue leading to 'primary' prevention of diverticulosis.