Diverticulosis pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Seyedmahdi Pahlavani, M.D.
Overview
The most important scenario behind the formation of Diverticula is, weakness in colon wall.
Pathogenesis
- Diverticula develop at well-defined points of weakness, which correspond to where the vasa recta penetrate the circular muscle layer of the colon[1][2]. File:2015-11-02 6-30-46.jpg
- A typical colonic diverticulum is a "false" or pulsion diverticulum, in which mucosa and submucosa herniate through the muscle layer,covered only by serosa.
Abnormal colonic motility is an important predisposing factor in the development diverticula. Patients with diverticulosis have exaggerated segmentation contractions in which segmental muscular contractions separate the lumen into chambers. It is hypothesized that the increase in intraluminal pressure predisposes to herniation of mucosa and submucosa[3][4].
- The development of diverticula specifically in the sigmoid colon can be explained by Laplace’s law according to which pressure (P) is proportional to wall tension (T) and inversely proportional to bowel radius (R), where k is a conversion factor (P = kT ÷ R). Since the sigmoid colon is the segment of the colon with the smallest diameter, it is the site of the highest pressure during segmentation of the colon[5].
Diverticular bleeding
As a diverticulum herniates, the penetrating vessel responsible for the wall weakness at that point becomes draped over the dome of the diverticulum, separated from the bowel lumen only by mucosa[1]Over time, the vasa recta is exposed to injury along its luminal aspect, leading to eccentric intimal thickening and thinning of the media. These changes may result in segmental weakness of the artery, predisposing to rupture into the lumen.[1]
Diverticulitis
The primary process is thought to be erosion of the diverticular wall by increased intraluminal pressure or inspissated food particles. Inflammation and focal necrosis ensue, resulting in perforation.
References
- ↑ 1.0 1.1 1.2 Meyers MA, Alonso DR, Baer JW (1976). "Pathogenesis of massively bleeding colonic diverticulosis: new observations". AJR Am J Roentgenol. 127 (6): 901–8. doi:10.2214/ajr.127.6.901. PMID 1087123.
- ↑ Meyers MA, Volberg F, Katzen B, Alonso D, Abbott G (1973). "The angioarchitecture of colonic diverticula. Significance in bleeding diverticulosis". Radiology. 108 (2): 249–61. doi:10.1148/108.2.249. PMID 4541643.
- ↑ MORSON BC (1963). "THE MUSCLE ABNORMALITY IN DIVERTICULAR DISEASE OF THE COLON". Proc. R. Soc. Med. 56: 798–800. PMC 1897181. PMID 14080071.
- ↑ Chia JG, Wilde CC, Ngoi SS, Goh PM, Ong CL (1991). "Trends of diverticular disease of the large bowel in a newly developed country". Dis. Colon Rectum. 34 (6): 498–501. PMID 1645247.
- ↑ PAINTER NS, TRUELOVE SC, ARDRAN GM, TUCKEY M (1965). "SEGMENTATION AND THE LOCALIZATION OF INTRALUMINAL PRESSURES IN THE HUMAN COLON, WITH SPECIAL REFERENCE TO THE PATHOGENESIS OF COLONIC DIVERTICULA". Gastroenterology. 49: 169–77. PMID 14323727.