Description

Diverticulum (single) or diverticula (multiple) are outpouchings of the colonic wall. Diverticular disease is a spectrum of diseases impacting the entire GI tract (except the rectum):

• Asymptomatic diverticulosis: common incidental finding on routine colonoscopy or imaging
• Symptomatic diverticulosis: also known as symptomatic uncomplicated diverticular disease (SUDD); recurrent abdominal pain attributed to diverticulosis without colitis or diverticulitis (1)
• Acute diverticulitis: diverticular disease with associated inflammation and/or infection
  • Uncomplicated diverticulitis: abdominal pain and leukocytosis without peritoneal signs or systemic toxicity
  • Complicated diverticulitis: secondary abscess formation, bowel obstruction, perforation, peritonitis, fistula, or stricture in the setting of diverticular inflammation
• Diverticular bleeding
  • Accounts for >40% of lower GI bleeds; often presents as painless hematochezia unless associated with active diverticulitis
  • Bleeding is more common with right-sided diverticula.

Epidemiology

Incidence

• Diverticular disease accounts for <300,000 hospitalizations per year in the United States.
• Diverticulitis occurs in 1–2% of the general population and in 4% of patients with diverticulosis over the course of their lifetime (1).
• Diverticular bleeding occurs in 3–5% of patients with diverticulosis.

Prevalence

• Prevalence of diverticulosis and the number of diverticula increase with age.
  • Diverticulosis occurs in 20% of those age 40 years, 60% of those age 60 years, and 70% by the age of 80 years.
  • Incidence of diverticulitis increased from 62 to 75/100,000 from 1998 to 2005; largest increase in patients <45 years of age—mostly due to changes in diet
• Male = female overall; more common in men <65 years of age and more common in women >65 years

Etiology and Pathophysiology

Diverticula form at points of weakness along the intestinal wall where small blood vessels (vasa recta) penetrate through the muscular layer of the colon.

• Age-related degeneration of the mucosal wall; increased intraluminal pressure from dense, fiber-depleted stools; and abnormal colonic motility contribute to diverticulosis
• Most right-sided diverticula are true diverticula (involves all layers of the colonic wall).
• Most left-sided diverticula are pseudodiverticula (outpouchings of the mucosa and submucosa only).
• Diverticulitis occurs when local inflammation and infection contribute to tissue necrosis with risk for mucosal micro- or macroperforation. Microscopy reveals inflammation with lymphocytic infiltrate, ulceration, mucin depletion, necrosis, Paneth cell metaplasia, and cryptitis.
• Alterations in intestinal microbiota contribute to chronic inflammation (1).
• Thinning of the vasa recta over the neck of the diverticula increases susceptibility to bleeding.
• Diverticular disease and irritable bowel syndrome may represent the same disease continuum.

Genetics

• Although genetics may play a role, there is no known genetic pattern.
• Asian and African populations have lower overall prevalence but develop diverticular disease with adoption of a Western lifestyle.

Risk Factors

• Age >40 years
• Low-fiber diet
• Sedentary lifestyle, obesity
• Previous diverticulitis. Risk rises with the number of diverticula.
• Smoking increases the risk of perforation (1).
• Risk of diverticular bleeding increases with NSAIDs, steroids, and opiate analgesics. Calcium channel blockers and statins protect against diverticular bleeding.

General Prevention

• High-fiber diet or nonabsorbable fiber (psyllium)
• Regular physical activity

Commonly Associated Conditions

Colon cancer, connective tissue diseases, obesity, irritable bowel syndrome, and inflammatory bowel disease