Overview and Risk Factors
Diverticula are herniations, or "outpouchings," of the colonic mucosa and submucosa through the muscularis layer. They occur at susceptible sites in the colonic wall, most commonly in areas where intramural blood vessels penetrate and weaken the muscular layer.
Diverticulosis indicates the presence of diverticula. When uncomplicated, the condition is asymptomatic. However, complications occur when diverticula become infected and inflamed (diverticulitis), which occurs in 10% to 20% of patients with diverticulosis, or when an adjacent blood vessel ruptures into a diverticulum, resulting in diverticular bleeding, which is the most common cause of lower gastrointestinal bleeding in the elderly.
Diverticulosis is usually asymptomatic, although patients may give a history of mild lower abdominal pain, cramping, bloating, constipation, and/or diarrhea. The discomfort is often relieved by bowel movements. Diverticulitis presents with fever, severe lower abdominal pain and tenderness, nausea, and vomiting. Diverticular bleeding may present as guiac-positive stools, iron-deficiency anemia, melena, or frank hematochezia.
As described below, the development of diverticula has been associated with a low-fiber diet. A lack of fiber renders the stool dry and low in bulk, requiring increased pressure to be generated by colonic contraction to propel the stool through the colon. Over time, this increased pressure is thought to result in the formation of diverticula. In contrast, high fiber intake results in stool that is of appropriate bulk and consistency, which may make the stools easier to pass.
Risk Factors
Advancing age. Diverticula are present in nearly half of Americans by age 60, and more than two-thirds of Americans over age 80 are affected. In contrast, less than 5% of people under age 40 are affected.
Geographic area. Industrialized countries have a much higher incidence of diverticular disease than developing nations. Some Western nations have prevalence rates that approach 40% of the population, whereas developing countries in Asia and Africa have prevalence well below 1%. Further, developing nations that adopt a more Western lifestyle have increased rates of diverticulosis.
Inadequate Dietary fiber intake. Several studies have linked low fiber intake to the development of diverticular disease (see Nutritional Considerations).
Total fat and red meat intake. High intake of total fat and red meat has also been correlated with a higher risk for diverticular disease.1
Sedentary lifestyle.
Diagnosis and Treatment
Diagnosis
Asymptomatic diverticulosis is often incidentally identified on colonoscopy, abdominal CT scan, or barium enema.
If diverticular bleeding is suspected, a colonoscopy may identify the site of bleeding and confirm the presence of diverticula. Upper GI endoscopy should also be performed to rule out upper GI bleeding.
Diverticulitis is suggested by the triad of left lower abdominal pain, fever, and leukocytosis. Abdominal CT scan is the diagnostic test of choice.
Colonoscopy and barium enema may increase the risk of colonic perforation and are contraindicated in acute diverticulitis.
Colonoscopy with biopsy to rule out colon cancer should be performed after the initial event has subsided.
Treatment
Nutrition is the primary consideration for prevention and treatment. The risk of developing diverticula may be reduced by increasing fiber intake, either through high-fiber foods or psyllium-based fiber supplements, along with other diet changes (see Nutritional Considerations below).
Uncomplicated diverticulitis is treated with bowel rest (no oral intake of food, drink, or medications) and intravenous antibiotics.
Patients with acute diverticulitis have a 40% risk of recurrence and 80% risk of recurrence following the second episode. Thus, recurrent cases of diverticulitis often require resection of the involved colon.
Diverticulitis complicated by fistula formation, colonic perforation, or bowel obstruction is treated emergently with resection of the involved portion of the colon and colostomy formation.
Diverticular bleeding, if severe or recurrent, may require immediate fluid resuscitation and blood transfusion, along with resection of the involved area of colon.
Nutrition is the primary consideration for prevention and treatment. The risk of developing diverticula may be reduced by increasing fiber intake, either through high-fiber foods or psyllium-based fiber supplements, along with other diet changes (see Nutritional Considerations).
Uncomplicated diverticulitis is treated with bowel rest (no oral intake of food, drink, or medications) and intravenous antibiotics.
Patients with acute diverticulitis have a 40% risk of recurrence and 80% risk of recurrence following the second episode. Thus, recurrent cases of diverticulitis often require resection of the involved colon.
Diverticulitis complicated by fistula formation, colonic perforation, or bowel obstruction is treated emergently with resection of the involved portion of the colon and colostomy formation.
Diverticular bleeding, if severe or recurrent, may require immediate fluid resuscitation and blood transfusion, along with resection of the involved area of colon.
Nutritional Considerations
Diverticular disease is associated with a fiber-poor diet, ie, a diet is low in fruits, vegetables, whole grains, and legumes, but high in animal products or refined foods. The following factors have been associated with a reduced risk of diverticular disease in epidemiologic studies:
A high-fiber diet. Fiber-poor diets result in diverticular formation and chronic inflammation that may progress to acute or chronic diverticulitis.2 Fiber may protect against colonic perforation by increasing stool weight and water content, resulting in a decreased fecal transit time and reduction of colonic segmentation pressures.3 Individuals eating generous amounts of insoluble fiber (eg, wheat bran, legumes, skin of fruit, nuts and seeds) have roughly a 40% lower risk of diverticular disease, compared to those consuming little dietary fiber.4 Not surprisingly, omnivores have a high (33%) incidence of diverticular disease, while vegetarians have a much lower incidence by comparison (12%).5
Avoiding meat. Eating a diet low in fiber and high in meat is associated with a 3-fold increased risk for symptomatic diverticular disease.1 In persons eating the largest amount of meat, the risk for right-sided diverticulosis in particular is roughly 25 times that of persons eating the least.6 It should be noted that fiber intake and meat intake are not entirely independent variables; like all animal products, meat contains no fiber.
During symptomatic episodes, avoiding solid foods and staying hydrated on a liquid diet may help. In patients with mild forms of diverticulitis, bowel rest using a liquid diet or intravenous fluids in combination with antibiotics is helpful.7
It should also be noted that high levels of physical activity may have a protective effect against diverticular disease. Constipation is a known risk factor for diverticulitis and is related to inactivity.8 While moderate physical activity has little protective effect, more intense activity, such as jogging or running, reduces risk by about 40%.9
Orders
See Basic Diet Orders chapter.
Exercise prescription.
What to Tell the Family
Diverticula are outpouchings of the lining of the gut caused by pressure building up from with the intestinal tract. This pressure appears to result from low-fiber diets and may be preventable by a high-fiber diet. In some individuals, these diverticula become infected, resulting in diverticulitis and necessitating antibiotics and bowel rest. Surgery is often required for persons who have repeat episodes of diverticulitis. This involves resection of the colon and placement of a colostomy, which often can be reversed if healing of the colon occurs without complications.
References
1. Aldoori WH, Giovannucci EL, Rimm EB, et al. A prospective study of diet and the risk of symptomatic diverticular disease in men. Am J Clin Nutr. 1994;60:757-764.
2. Floch MH, Bina I. The natural history of diverticulitis: fact and theory. J Clin Gastroenterol. 2004;38(suppl 1):S2-S7.
3. Morris CR, Harvey IM, Stebbings WSL, et al. Epidemiology of perforated colonic diverticular disease. Postgrad Med J. 2002;78:654-658.
4. Aldoori WH, Giovannucci EL, Rockett HR, Sampson L, Rimm EB, Willett WC. A prospective study of dietary fiber types and symptomatic diverticular disease in men. J Nutr. 1998;128:714-719.
5. Gear JS, Ware A, Fursdon P, et al. Symptomless diverticular disease and intake of dietary fibre. Lancet. 1979;1:511-514.
6. Lin OS, Soon MS, Wu SS, et al. Dietary habits and right-sided colonic diverticulosis. Dis Colon Rectum. 2000;43:1412-1418.
7. Petrakis I, Sakellaris G, Kogerakis N, et al. New perspectives in the management of sigmoid diverticulitis. Panminerva Med. 2001;43:289-293.
8. Simren M. Physical activity and the gastrointestinal tract. Eur J Gastroenterol Hepatol. 2002;14:1053-1056.
9. Aldoori WH, Giovannucci EL, Rimm EB, et al. Prospective study of physical activity and the risk of symptomatic diverticular disease in men. Gut. 1995;36:276-282.
