What is the role of diverticulosis in the pathophysiology of lower GI bleeding (LGIB)?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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Answer

Diverticulosis is a common acquired condition in Western societies; approximately 50% of adults older than 60 years have radiologic evidence of this disease. A diverticulum is a saclike protrusion of the colonic wall that develops at a small point of weakness where the penetrating vessel has perforated through the circular muscle fibers. The vessel becomes draped over the dome of the diverticulum, separated from the bowel lumen only by the mucosa. Subsequent chronic trauma to the vasa recta along the luminal aspect, as well as contraction and relaxation of the surrounding muscularis propria, leads to an eccentric thinning of the media. Ultimately, erosion of the vessel and bleeding can occur.

Diverticula are most commonly located in the sigmoid and descending colon, and diverticular bleeding originates from vasa rectae located in the submucosa, which can rupture at the dome or the neck of the diverticulum. [11] Up to 20% of patients with diverticular disease experience bleeding, which stops spontaneously in 80% of patients; however, in 5% of patients with diverticular disease, the bleeding from diverticular disease can be massive.

Although about 75% of the diverticula occur on the left side of the colon, right-sided diverticula are responsible for approximately 50%-90% of the bleeding. [11] This may be because false right-sided diverticula have wider necks and domes, which expose the vasa recta to injury over a greater length. The incidence of true right-sided diverticula is uncommon (1%-2%) in the United States, unlike in Asian populations. True right-sided diverticula are usually solitary and originate in the anterior cecum adjacent to the ileocecal valve. Often, true right-sided diverticula cause right-sided diverticulitis and are misdiagnosed as appendicitis.


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