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 7th 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.
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
- Diverticulosis: the presence of multiple colonic diverticula without evidence of infection 
- In the US, ∼ 50% of individuals > 60 years have diverticulosis 
- 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)
- Low physical activity
- Increasing age
- Other causes: genetic factors
- Connective tissue disorders (e.g., , ) 
The formation of diverticula is considered multifactorial.
- Increased intraluminal pressure, e.g., due to chronic constipation
- Weakness of the intestinal wall
- Localized particularly in the sigmoid colon
Asymptomatic diverticulosis 
- Typically an incidental diagnosis
- No workup required
Symptomatic diverticulosis 
- Colonoscopy: diagnostic modality of choice for suspected symptomatic diverticulosis 
Double-contrast barium enema: highly sensitive test to detect diverticulosis but not commonly performed 
- Consider in the workup of the following: 
- Contraindications: suspected diverticulitis or perforated diverticulum 
- Findings: outpouching of the colonic wall of variable size
- Abdominal ultrasound
Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis.
- Dietary modification, e.g., high-fiber diet, , or vegetarian diet 
- Weight reduction
- Vigorous physical activity
- Smoking cessation
- Treatment of alcoholism
Diverticular bleeding 
- 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
- Differential diagnosis: other causes of (e.g., hemorrhoidal bleeding)
- Treatment: See “ .”
- Acute inflammation: i.e.,
- Chronic inflammation: Diverticular disease-associated colitis (DAC), also called diverticular colitis or segmental colitis associated with diverticulosis (SCAD) 
We list the most important complications. The selection is not exhaustive.