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Diverticulosis, Small Intestinal
Updated: Apr 12, 2006
Introduction
Background
Small intestinal diverticulosis refers to the clinical entity characterized by the presence of multiple saclike mucosal herniations through weak points in the intestinal wall. Small intestinal diverticula are far less common than colonic diverticula. The singular form is diverticulum, and the plural form is diverticula.
Pathophysiology
The cause of this condition is not known. It is believed to develop as the result of abnormalities in peristalsis, intestinal dyskinesis, and high segmental intraluminal pressures.The resulting diverticula emerge on the mesenteric border, ie, sites where mesenteric vessels penetrate the small bowel. Diverticula are classified as true and false. True diverticula are composed of all layers of the intestinal wall, whereas false diverticula are formed from the herniation of the mucosal and submucosal layers. Meckel diverticulum is a true diverticulum.
Diverticula can be classified as intraluminal or extraluminal. Intraluminal diverticula and Meckel diverticulum are congenital. Extraluminal diverticula may be found in various anatomic locations and are referred to as duodenal, jejunal, ileal, or jejunoileal diverticula.
Frequency
United States
Duodenal diverticula are approximately 5 times more common than jejunoileal diverticula. The actual incidence of both types of diverticula is not known because these lesions are usually asymptomatic. The incidence at autopsy of duodenal diverticula is 6-22%. Jejunal diverticula are less common, with a reported incidence of less than 0.5% on upper GI radiographs and a 0.3-1.3% autopsy incidence.
International
Incidence parallels that in the United States.
Mortality/Morbidity
Small bowel diverticula are generally asymptomatic, with the exception of Meckel diverticulum. Major complications include diverticulitis, GI hemorrhage, intestinal obstruction, acute perforation, and pancreatic and/or biliary disease in duodenal diverticula. Mortality is influenced by patients' age, nature of complications, and timeliness of intervention.
Race
No racial predilection exists.
Sex
Duodenal diverticula occur in equal numbers of men and women, while a slight male preponderance exists in jejunoileal diverticula.
Age
Most cases of duodenal diverticula are observed in patients older than 50 years, while jejunoileal diverticula are commonly observed in patients aged 60-70 years. Reports of this condition in young adults exist as well.
Clinical
History
Most patients with small bowel diverticula are asymptomatic. Patients who develop symptoms generally report symptoms that reflect associated complications. The most common symptom is nonspecific epigastric pain or a bloating sensation. Complication rates as high as 10-12% for duodenal diverticulosis and 46% for jejunal diverticulosis have been reported. These complications include the following:
- Diverticular pain - Abdominal pain in the absence of other complications (can be the only manifestation of small bowel diverticulosis)
- Bleeding - Hematochezia, melena, or obscure bleeding that leads to iron deficiency
- Diverticulitis - Fever and localized tenderness associated with inflammation
- Intestinal obstruction - Colicky abdominal pain, constipation, nausea, vomiting
- Perforation and localized abscess - Fever, abdominal pain with or without signs of peritonitis
- Malabsorption - Diarrhea, flatulence, weight loss
- Anemia - Fatigue, leg swelling
- Biliary tract disease - Biliary colic
- Volvulus - Intestinal obstruction
- Enteroliths - Intestinal obstruction
Physical
Physical findings are also related to the complications mentioned above. These findings include abdominal fullness, localized or vague tenderness, rectal bleeding, and melena.
- No set of symptoms or signs is pathognomonic for small bowel diverticulosis. In the absence of complications, history and physical examination findings are often negative.
- Some of these symptoms may be manifestations of other unrelated comorbid conditions. The exact rate of these complications is difficult to estimate but has been reported to be from 10-40%.
- Hemorrhage and pancreaticobiliary disease are the most common complications of duodenal diverticulum, while diverticulitis and perforation are more common with jejunoileal diverticula. Intestinal obstruction is a feature of intraluminal duodenal diverticulum, while Meckel diverticulum can be complicated by peptic ulcer infection and intestinal obstruction. Most patients are diagnosed serendipitously.
- Specific features based on anatomic location and type
- Duodenal diverticula: These vary from a few millimeters to several centimeters and may be multiple. Approximately 75% occur within 2 cm of the ampulla of Vater (juxtapapillary). This anatomic location is of clinical significance. It is associated with increased incidence of biliary stones, pancreatitis, and biliary and pancreatic anomalies. Incidence increases with age. Fifty percent of cases have associated colonic pseudodiverticulosis.
- Jejunoileal diverticula: Duodenal and Meckel diverticulum excluded, small bowel diverticula are most common in the proximal jejunum. They usually are multiple and vary from a few millimeters to 10 cm. They are located on the mesenteric border within the leaves of the mesentery. These lesions are frequently associated with small intestine motility disorders, such as progressive systemic sclerosis, visceral myopathy, and visceral neuropathies.
- Intraluminal diverticula: These are congenital diverticula resulting from defective recanalization of duodenal lumen during fetal development. These structures are believed to start as fenestrated diaphragm that, over time, transforms into diverticulum as a result of peristalsis. It occurs singly and has duodenal mucosa on both sides. Intraluminal diverticula are usually located in the second part of the duodenum and can manifest at any age.
- Meckel diverticulum: This congenital diverticulum results from incomplete closure of the vitelline duct during fetal development. It is the most common true diverticulum of the GI tract. Incidence at autopsy is approximately 25%. Meckel diverticulum is generally asymptomatic, causing symptoms in only 2% of adults. The mucosa occasionally contains heterotopic gastric mucosa that is often responsible for peptic ulceration and bleeding.
Causes
The following risk factors apply to acquired pseudodiverticula:
- Low-fiber diet
- High-fat diet
- Advancing age
- Heredity: No evidence indicates that heredity plays a role in the development of small bowel diverticula.
- Systemic sclerosis
- Visceral myopathy
- Visceral neuropathy
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References
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Isselbacher KJ, Ebstein A. Diverticular, vascular and other disorders of the intestine and peritoneum. In: Fauci A, ed. Harrison's Principles of Internal Medicine. New York, NY:. McGraw-Hill Inc;1998:1648-1649.
Mark B. Small Intestine. In: Seymour I, Schwartz G, eds. Principles of Surgery. New York, NY:. McGraw-Hill Inc;1999:1247-1249.
Rubesin SE. Simplified approach to differential diagnosis of small bowel abnormalities. Radiol Clin North Am. Mar 2003;41(2):343-64, vii. [Medline].
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Further Reading
Keywords
diverticular disease of the small bowel, mucosal herniations, abnormalities in peristalsis, intestinal dyskinesis, high segmental intraluminal pressures, true diverticula, false diverticula, Meckel's diverticulum, intraluminal diverticula, extraluminal diverticula, duodenal diverticula, jejunal diverticula, ileal diverticula, jejunoileal diverticula, diverticulitis, GI hemorrhage, intestinal obstruction, acute perforation, pancreatic disease, biliary disease
Overview: Diverticulosis, Small Intestinal