Diverticulosis

Diverticulosis is a type of diverticular disease that consists of the formation of abnormal outpouchings of the colonic mucosa (diverticula). These can develop due to a combination of chronically elevated intraluminal pressures due to chronic constipation (e.g., due to low-fiber diets, lack of physical exercise) and age-related weakening of connective tissue. This typically causes the colonic mucosa to herniate through areas of weakness in the muscular layer. The sigmoid colon is most commonly involved. Incidence increases with age, and approx. 50% of individuals are affected by the 7^th decade of life. Diverticulosis is typically asymptomatic but occasionally presents with altered bowel habits and/or abdominal discomfort. It is often an incidental finding during the diagnostic evaluation of abdominal pain and other gastrointestinal conditions. Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis but is contraindicated if acute inflammation of the diverticula (i.e., diverticulitis) is suspected. Management is typically aimed at preventing disease progression and treating complications, e.g., diverticulitis, painless diverticular bleeding (an important cause of severe lower GI bleeding), and diverticular disease-associated colitis (chronic inflammation of diverticula and surrounding colonic mucosa).

See also “Diverticulitis.”

• Diverticula: blind pouches that protrude from the gastrointestinal wall and communicate with the lumen
  • True diverticulum; : a type of diverticulum that affects all layers of the intestinal wall.
    • Rare (except Meckel diverticulum )
    • Typically congenital
    • Most commonly occur in the cecum
    • Occur less commonly in the colon
  • False diverticulum or pseudodiverticulum: type of diverticulum that involves only the mucosa and submucosa and does not contain muscular layer or adventitia.
    • Most common type of gastrointestinal diverticula
    • Typically acquired
    • Localized particularly in the sigmoid colon
• Diverticulosis: the presence of multiple colonic diverticula without evidence of infection ^[1]

• In the US, ∼ 50% of individuals > 60 years have diverticulosis ^[2]
• More common in high-income countries due to the higher prevalence of a high-fat, low-fiber diet

Epidemiological data refers to the US, unless otherwise specified.

• Caused mainly by lifestyle and environmental factors
  • Diet (low-fiber, rich in fat and red meat)
  • Obesity
  • Low physical activity
  • Increasing age
  • Smoking
  • Intestinal microbiome
• Other causes: genetic factors
  • Connective tissue disorders (e.g., Marfan syndrome, Ehler-Danlos syndrome) ^[1][3]
  • Autosomal dominant polycystic kidney disease

References:^[4][5]

The formation of diverticula is considered multifactorial.

• Increased intraluminal pressure, e.g., due to chronic constipation
• Weakness of the intestinal wall
  • Age-related loss of elasticity of the connective tissue
  • Physiological gaps in the intestinal wall, which occur where blood vessels penetrate, predispose to protrusion and herniation of intestinal mucosa and submucosa.

• Usually asymptomatic
• May manifest with abdominal discomfort or pain, especially if associated with chronic constipation ^[6]
• Diverticular bleeding ^[7]

Asymptomatic diverticulosis ^[8]

• Typically an incidental diagnosis
• No workup required

Symptomatic diverticulosis ^{[9][10][11][12][13]}

• Colonoscopy: diagnostic modality of choice for suspected symptomatic diverticulosis ^[12]
  • Indications
    • Lower GI bleed
    • Recurrent abdominal pain and/or diarrhea
    • Concern for underlying malignancy ^[13]
  • Findings: well-defined outpouching from the colonic wall
  • Avoid if acute diverticulitis is suspected.
  • Biopsy and histological analysis can be performed, if necessary
• Double-contrast barium enema: highly sensitive test to detect diverticulosis but not commonly performed ^[9]
  • Consider in the workup of the following: ^[10]
    • Recurrent LLQ pain without signs of acute inflammation
    • Altered bowel habits
    • Lower GI bleed in a hemodynamically stable patient if colonoscopy cannot be performed
  • Contraindications: suspected diverticulitis or perforated diverticulum ^[11][13]
  • Findings: outpouching of the colonic wall of variable size
• Abdominal ultrasound
  • Indications: may be performed as part of the workup for nonspecific LLQ pain ^[11]
  • Findings: hypoechoic or anechoic outpouching from the colonic wall ^[13]

Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis.

• Asymptomatic diverticulosis
  • No treatment can reverse the growth of existing diverticula.
  • The goal is the prevention of progression (see “Prevention”).
• Symptomatic uncomplicated diverticular disease: unclear ^[6][12]
• Complicated diverticular disease (e.g., diverticulitis): See “Complications.”

Consider the following measures to prevent disease progression and development of complications. See “Management of diverticulitis” for secondary prevention of recurrent diverticulitis. ^[14][^[15]

• Dietary modification, e.g., high-fiber diet, DASH diet, or vegetarian diet ^[16]
• Weight reduction
• Vigorous physical activity
• Smoking cessation
• Treatment of alcoholism

• Diverticular bleeding ^[17][18]
  • Epidemiology
    • Diverticulosis is the most common cause of lower GI bleeding in adults.
    • Occurs in ∼ 5% of individuals with diverticulosis
  • Etiology: erosions around the edge of diverticula
  • Clinical findings
    • Painless hematochezia
    • Signs of anemia may be present if recurrent
    • Severe or ongoing bleeding: significant drop in hemoglobin → hemodynamic instability (hypotension, tachycardia, dizziness, reduced level of consciousness)
    • In 70–80% of cases, bleeding ceases spontaneously
  • Differential diagnosis: other causes of lower gastrointestinal bleeding (e.g., hemorrhoidal bleeding)
  • Treatment: See “Initial management of overt GI bleeding.”
    • Endoscopic hemostasis during colonoscopy (e.g., epinephrine injection, thermal coagulation, ligation)
    • Angiography with vessel embolization
• Acute inflammation: i.e., diverticulitis
  • Clinical features include left lower quadrant pain, low-grade fever, tender palpable mass, change in bowel habits
  • Downstream complications include GI perforation, abscess, fistula, intestinal obstruction, and pylephlebitis. ^[17]
• Chronic inflammation: Diverticular disease-associated colitis (DAC), also called diverticular colitis or segmental colitis associated with diverticulosis (SCAD) ^[19]
  • Multifactorial inflammation of segments of colonic mucosa and diverticula
  • May overlap with IBD and is treated similarly to Crohn disease

We list the most important complications. The selection is not exhaustive.