Diverticular disease encompasses a set of colonic pathologies that result from abnormal outpouchings of the colonic mucosa (diverticula). It includes diverticulosis (noninflamed diverticula) and diverticulitis (inflamed diverticula). Colonic diverticula 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 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 may manifest with lower gastrointestinal bleeding, altered bowel habits, and/or abdominal pain. Diverticulitis may remain localized (mild uncomplicated diverticulitis) or progress, resulting in complications such as abscess or perforation (complicated diverticulitis). Diverticulitis typically manifests with fever and left lower quadrant abdominal pain (as the sigmoid colon is most commonly involved). Colonoscopy is the diagnostic modality of choice for symptomatic diverticulosis but is contraindicated if acute diverticulitis is suspected. Abdominal CT scan with IV contrast is preferred in suspected acute diverticulitis. Uncomplicated diverticulitis usually responds to conservative management with bowel rest and analgesics; oral broad-spectrum antibiotics are reserved for patients at high risk of complications. In complicated diverticulitis, management consists of parenteral antibiotics, treatment of any complications, and, in some cases, emergency colonic resection. Once the acute phase has resolved, a colonoscopy is indicated to rule out malignancy. Elective colectomy is recommended for all patients with complicated diverticulitis that is managed conservatively. The procedure is not routinely indicated for uncomplicated 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 
- Diverticulitis: inflammation or infection of colonic diverticula
- 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., , ) 
Diverticulosis: 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
- Usually asymptomatic
- May manifest with abdominal discomfort; or pain, especially if associated with chronic constipation
- Low-grade fever
- Sigmoid colon most commonly affected → left lower quadrant pain
- Possibly tender, palpable mass (pericolonic inflammation)
- Change in bowel habits (constipation in ∼ 50% of cases and diarrhea in 25–35% of cases)
- Nausea and vomiting (caused by bowel obstruction or ileus)
- peritonitis: indicates possible perforation and
- ↑ Urinary urgency and frequency (in ∼ 15% of cases)
- Rarely: hematochezia
In elderly or immunocompromised patients, clinical symptoms may only be mild.
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
Suspect acute diverticulitis in adult patients presenting with LLQ pain, fever, and leukocytosis. The diagnosis is confirmed with imaging, preferably with IV contrast-enhanced CT scan. Once the acute phase has resolved, a colonoscopy should be performed to rule out malignancy. Colonoscopy is contraindicated in the acute phase because of the risk of perforation.
Laboratory studies 
- Routine tests
- Tests to rule out common differential diagnoses
CT abdomen and pelvis with IV contrast 
- Supportive findings
- Colonic outpouching
- Signs of inflammation
- Bowel wall thickening > 3 mm
- Peridiverticular mesenteric fat stranding
- Complications may also be identified
- MRI abdomen and pelvis (without and with IV contrast)
- Ultrasound abdomen
Abdominal x-ray 
- Not useful in diagnosing uncomplicated diverticulitis
- Findings that may be seen in complicated diverticulitis include
Screening colonoscopy 
- Recommended 6–8 weeks after the resolution of the acute episode to assess the extent of diverticulitis and rule out malignancy 
- Colonoscopy is contraindicated during an acute episode because of the increased risk of perforation.
- Not required if a recent evaluation of the colon has been performed 
Classification of diverticulitis
- To choose the best treatment approach and determine the prognosis, identifying the stage of acute diverticulitis is recommended. 
- Uncomplicated diverticulitis: localized inflammation of a colonic diverticulum with no evidence of complications (i.e., Modified Hinchey stage 0 and stage Ia)
- Complicated diverticulitis: inflammation of a colonic diverticulum associated with complications such as perforation, abscess, fecal peritonitis, bowel obstruction, or fistula formation (i.e., Modified Hinchey stages Ib–IV) 
- The modified Hinchey classification is based on CT findings and is the most commonly used classification.
|Modified Hinchey classification of diverticulitis |
- Differential diagnoses of uncomplicated acute diverticulitis
- Differential diagnoses of perforated diverticulitis: See .
- See for a more comprehensive list.
The differential diagnoses listed here are not exhaustive.
Management of diverticulosis
- No treatment can reverse the growth of existing diverticula.
- The goal is the prevention of progression (see “Prevention of recurrence and disease progression” below).
- Symptomatic diverticulosis: see “Treatment” in
Management of diverticulitis 
- Uncomplicated diverticulitis (Modified Hinchey stage 0 and stage Ia)
- Complicated diverticulitis (Modified Hinchey stages Ib–IV)
Uncomplicated diverticulitis 
Antibiotic therapy: Not routinely recommended 
- Indications 
- Consider one of the following commonly used broad-spectrum oral antibiotics 
- See also
- Duration of antibiotic therapy: 4–7 days 
- Supportive care
- Outpatient treatment
- Follow-up in 2–3 days for evaluation of progression (earlier if symptoms worsen)
- No improvement: Consider inpatient management; repeat imaging to evaluate for complications.
- Screening colonoscopy once symptoms have resolved.
- Consider elective colectomy for recurrent uncomplicated diverticulitis.
- GI consultation for patients with frequent, recurrent episodes or chronic symptoms 
Complicated diverticulitis  
- Antibiotic therapy: broad-spectrum IV antibiotics are routinely recommended (see )
- Supportive care
Management of complications
- Size < 4 cm: trial of conservative management with IV antibiotics
- Size ≥ 4 cm
- Perforation with generalized peritonitis; (i.e., clinical signs of diffuse peritonitis or modified Hinchey stage III and stage IV on imaging): emergency surgery 
- Bowel obstruction
- Abscess 
- Additional considerations
Elective colectomy 
- Routinely recommended 6–8 weeks after resolution of complicated diverticulitis
- Select groups of patients after resolution of uncomplicated diverticulitis, including: 
- Patients at high risk of recurrence with complications 
- Patients with persistent abdominal symptoms after resolution of an acute episode
- Chronic complications of diverticulitis (e.g., fistula, colonic strictures)
- Procedure: laparoscopic or open colectomy 
Prevention of recurrence and disease progression 
- High-fiber diet 
- Fluid hydration
- Weight reduction
- Vigorous physical activity
- Cessation of smoking
- Avoid nonaspirin NSAID use, if possible.
- Clear liquid diet
- Supportive care
- Consider broad-spectrum oral antibiotics in patients at high risk for complications (not routinely indicated). 
- Outpatient treatment with follow-up in 2–3 days or earlier if symptoms worsen
- Refer for colonoscopy after the resolution of symptoms
Complicated diverticulitis 
- Urgent surgery consult
- Broad-spectrum IV antibiotics: See empiric antibiotic therapy for intra-abdominal infections.
- Manage complications, if present.
- Parenteral analgesics (see acute pain management)
- Parenteral antiemetics
- Inpatient treatment
- Serial abdominal examination for patients not undergoing emergency surgery
- Refer for colonoscopy after the resolution of symptoms
Diverticular bleeding 
- Etiology: erosions around the edge of diverticula
- Clinical findings
- Differential diagnosis: other causes of (e.g., hemorrhoidal bleeding)
Colovesical (most common)
- Diagnosis: CT with oral contrast
- Other forms: colovaginal, coloenteric, colocutaneous
- Colovesical (most common)
- Inflammation (diverticulitis)
- Intestinal obstruction
We list the most important complications. The selection is not exhaustive.
- One-Minute Telegram 21-2021-2/3: Amoxicillin-clavulanate: An alternative to fluoroquinolones in treating diverticulitis?
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