Diverticulum(redirected from allantoic diverticulum)
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a pouch formed by the congenital or acquired protrusion of the wall of a tubular organ in man. Most frequently encountered are diverticula of the esophagus or urinary bladder and more rarely, of the duodenum or stomach. Congenital diverticula are associated with defects in the development of the organ. Acquired diverticula arise as a result of pressure from the organ cavity on its wall, which has been weakened either by a pathological process (trauma, inflammation), or they may result from congenital muscular weakness of the wall (pouch-like protrusion). Diverticula may develop when diseases of neighboring organs result in a pulling on the organ wall by cicatrices and adhesions (funnel-shaped protrusion). After it has entered a diverticulum, the content of an organ is retained there for some time; later the diverticulum is evacuated. The diverticulum gradually stretches and becomes enlarged, and evacuation becomes difficult. The stagnant content irritates the mucous membrane of the diverticulum and becomes infected. Inflammation of the walls of the diverticulum develops—diverticulitis (catarrhal, ulcerative, or phlegmonous; perforation of the diverticulum is possible). A diverticulum of the esophagus may manifest itself by difficulty of food passage and vomiting and a diverticulum of the urinary bladder, by difficulty in urinating. An intestinal diverticulum sometimes causes obstruction. Treatment depends on the site and the course of the illness; in some cases surgery is necessary.