Pathogenesis of colonic diverticular disease.

PURPOSE: This paper aims to review the current evidence regarding pathogenesis of colonic diverticular disease and its complications, which are a major health problem in the Western world.
METHODS: Based on selective Medline searches, relevant literature was indentified regarding pathogenesis of (1) diverticulosis/formation of diverticula, (2) diverticulitis/inflammation of diverticula, (3) complicated diverticulitis/perforation, and (4) diverticular bleeding.
RESULTS: Pathogenesis of colonic diverticula is regarded as a multifactorial process, involving dietary factors (Western low-fiber diet), structural changes of the colonic wall (altered musculature, collagen, elastin, etc.) and functional changes (motility disorder, increased intraluminal pressure). Genetic changes are also discussed and aging is also a key factor. Pathogenesis of inflammation (diverticulosis) is regarded as a result of "microperforations" at the fundus of the diverticulum, and not an "abscessed diverticulum" due to an impacted fecolith. Histamine and its receptors do also seem to play a role, corresponding with the promising prophylactic approach with probiotics. Pathogenesis of complicated diverticulitis is characterized by perforation, which is the cardinal feature. Furthermore, an intensive inflammatory infiltrate with macrophages is found in surgical specimens, even after antibiotic pretreatment. Steroid intake and immunosuppression are risk factors and only recently a glucocorticoid-induced tumor necrosis factor-receptor has been suggested to resemble the molecular link. Diverticular bleeding is a distinct disease process-which does usually take place without diverticulitis-and is due to eccentric rupture of the vas rectum.
CONCLUSIONS: The pathophysiology of diverticular disease is multifactorial. Some of the current evidence has important implications for clinical practice, e.g., the suggested role of steroid intake and immunosuppression for complicated diverticulitis.