Diverticula are sac-like protrusions of the bowel wall and occur throughout the small and large bowel. Small bowel diverticula are usually asymptomatic and are discovered incidentally. This topic will review the clinical manifestations, diagnosis, and management of small bowel diverticula with the exception of Meckel's diverticulum. The clinical manifestations, diagnosis, and management of Meckel’s diverticulum and the epidemiology and pathophysiology of colonic diverticular disease, the treatment of diverticulitis, and diverticular bleeding are discussed separately. (See "Lower gastrointestinal bleeding in children: Causes and diagnostic approach", section on 'Meckel's diverticulum' and "Colonic diverticulosis and diverticular disease: Epidemiology, risk factors, and pathogenesis" and "Clinical manifestations and diagnosis of acute diverticulitis in adults" and "Colonic diverticular bleeding".)
Duodenal diverticula have been reported in 2 to 5 percent of patients undergoing barium studies of the upper gastrointestinal tract and in 7 percent of patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) . Jejunal diverticula have been reported in up to 1 to 2 percent of patients in autopsy series .
Small bowel diverticula occur most frequently in the duodenum. In one retrospective review of 208 patients with symptomatic small bowel diverticulosis, diverticula were located in the duodenum in 79 percent, in the jejunum or ileum in 18 percent, and in all three segments in 3 percent .
ETIOLOGY AND PATHOGENESIS
Duodenal diverticula usually occur near the papilla of Vater [1,3]. Less than 10 percent of duodenal diverticula are located in the first and fourth part of the duodenum. The vast majority of duodenal diverticula are extraluminal and are thought to be acquired as a result of herniation through a defect caused by the entrance of large vessels [1,4,5]. Intraluminal diverticula are usually congenital and result from incomplete canalization of the intestinal lumen after the embryonic proliferative epithelial stage, producing a duodenal diaphragm or web . Intraluminal diverticula are lined on both sides with duodenal mucosa, and an eccentric opening is usually proximal in the sac. Extraluminal duodenal diverticula are associated with an increased risk of pigment stones, possibly due to bacterial contamination of the biliary tree due to stasis within the diverticula and deconjugation of bilirubin glucuronide [1,5].
Jejunal diverticula are usually multiple and localized to the proximal jejunum. Jejunoileal diverticula may be composed of mucosa and submucosa only, or of all layers of the jejunal wall. They are frequently associated with disorders of intestinal motility, such as progressive systemic sclerosis, visceral neuropathies, and myopathies. Familial aggregation has been described in case series, suggesting that some cases may be heritable [7,8]. The cause of jejunoileal diverticula is unclear, but abnormalities in peristalsis, intestinal dyskinesia, and high intraluminal pressure have been implicated in the pathogenesis. In patients with visceral myopathy, atrophy of the jejunal wall from one side and increased luminal pressure from the other may lead to the protrusion of the small intestinal mucosa through the defects in the lamina muscularis mucosae, resulting in the formation of small intestinal diverticula .