Colonic Diverticulitis: A Clinical Practice Update From the AGA

The American Gastroenterological Association provides best practice advice to assist gastroenterologists in making an accurate diagnosis and providing optimal treatment for patients with colonic diverticulitis.

The American Gastroenterological Association (AGA) has developed a clinical practice update for managing patients with colonic diverticulitis.  This guidance has been published in Gastroenterology.

The update includes 14 best practices that are based on a review of meta-analyses, randomized controlled trials, observational studies, and systematic reviews.

Among patients with diverticulitis, the most common presenting symptom is abdominal pain that is usually acute or subacute in onset and located in the left lower quadrant. Other symptoms include fever, a change in bowel habits, nausea without vomiting, and an increased white blood cell count and/or C-reactive protein (CRP) level. A clinical suspicion of diverticulitis is correct in 40% to 65% of patients, and computed tomography (CT) is often necessary to make a diagnosis, according to the study authors.

“CT scan of the abdomen and pelvis with oral and intravenous contrast is highly accurate for diagnosing diverticulitis (sensitivity/specificity 95%),” noted the researchers.

A colonoscopy is recommended after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis. However, colonoscopy may be deferred if a recent (within 1 year) high-quality colonoscopy was performed and there were no findings necessitating a more immediate follow-up.

“Patients with recurrent uncomplicated diverticulitis should follow routine colorectal cancer screening and surveillance intervals unless alarm symptoms are present,” the research group commented. “Alarm symptoms include change in stool caliber, iron deficiency anemia, blood in stool, weight loss, and abdominal pain.”

Ongoing gastrointestinal symptoms, including periodic abdominal pain, are frequently experienced by patients after an episode of acute diverticulitis. “While visceral hypersensitivity is the likely cause in the majority of cases, ongoing diverticular inflammation, a diverticular stricture or fistula, and alternative diagnoses like ischemic colitis, constipation, and inflammatory bowel disease should be excluded with both imaging (CT scan abdomen/pelvic with oral and intravenous contrast) and lower endoscopy,” advised the study authors.

Patients often report experiencing comfort while adhering to a clear liquid diet in the acute phase of diverticulitis, potentially because diverticulitis can cause a mechanical obstruction and/or may be secondary to the systemic inflammation associated with this disease. “It is reasonable to advise a clear diet during the acute phase of uncomplicated diverticulitis with the goal of patient comfort,” noted the study group.

Guidelines recommend that antibiotics be used selectively in patients with acute uncomplicated diverticulitis. Although antibiotics have been used as first-line therapy for acute uncomplicated diverticulitis, recent evidence suggests that there is no benefit to this use in immunocompetent patients with mild acute uncomplicated diverticulitis, according to the researchers.

“Patients who are immunocompromised are [at] high risk for complications and should be treated with antibiotics,” the study group stated. “Likewise, antibiotics are mandatory for the treatment of diverticulitis complicated by evidence for systemic inflammation, abscess, perforation, or obstruction.”

When antibiotic treatment is necessary, broad-spectrum agents with gram-negative and anaerobic coverage are usually included in the regimen.

Patients who have an impaired immune system and diverticulitis may present with milder signs and symptoms compared with those who are immunocompetent. “Therefore, [CT] should be considered to make a diagnosis and to rule out complications,” the researchers advised. “Patients with uncomplicated diverticulitis who are immunosuppressed are [at] high risk for progression to complicated diverticulitis and/or sepsis and should be treated with antibiotics.”

Risk factors for incident diverticulitis include diet, lifestyle, medications, and genetics. A diet that is high in fiber from fruits, vegetables, whole grains, and legumes and low in red meat and sweets and a vegetarian diet are associated with a decreased risk of incident diverticulitis, according to the study group. Vigorous physical activity has also been found to decrease the risk of disease.

Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) increases the risk of diverticulitis, and the risk is greater for nonaspirin NSAIDs than for aspirin, noted the researchers. Genetics can also play a role in the risk of diverticulitis.

Complications from diverticulitis, excluding fistula formation, occur more frequently with the first episode of diverticulitis than with subsequent episodes, noted the study group. Patients with diverticulitis are at risk of recurrence, with 20% having 1 or more recurrent episodes within 10 years. In addition, approximately 8% of patients with incident disease have recurrences within the first year after complete recovery from the incident episode, and 20% have recurrences within 10 years. The risk of recurrence of diverticulitis increases with subsequent episodes.

According to the researchers, an elective segmental resection should not be advised based on the number of diverticulitis episodes, and with a few exceptions, new surgical guidelines recommend a more case-by-case approach. “Elective segmental colectomy reduces, but does not eliminate, diverticulitis risk,” the study group noted.

Patients who have a history of complicated diverticulitis that has been successfully managed without surgery are at increased risk for recurrence and complicated recurrence. After recovery from an episode of acute diverticulitis that was successfully managed without surgery, a patient who is chronically immunosuppressed should consult with a colorectal surgeon, advised the study group. “This population is [at] high risk for complicated recurrence and the goal of surgery is to prevent complicated diverticulitis,” the researchers stated.

“While the majority of patients never experience a perforation or abscess, uncomplicated recurrences are a burden to patients,” the study group commented. “Patients often blame themselves for episodes and worry about recurrence, perforation, and need for surgery. Gastroenterologists can alleviate many of these concerns by making an accurate diagnosis, addressing chronic sequalae, and educating patients on risk factors, prognosis, and indications for surgery. While the advice in this document is based on low to moderate quality evidence, research is ongoing and has the potential to eventually identify better options for diverticulitis treatment and prevention.”

This expert review was commissioned and approved by the AGA Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board and underwent internal peer review by the CPUC and external peer review through Gastroenterology.

Summary of AGA Best Practice Advice Statements on Colonic Diverticulitis

CT imaging should be considered to confirm the diagnosis of diverticulitis in patients without a prior imaging-confirmed diagnosis and to evaluate for potential complications in patients with severe presentations; imaging should also be considered in those who fail to improve with therapy, who are immunocompromised, or who have multiple recurrences and are contemplating prophylactic surgery in order to confirm the diagnosis and location(s) of disease.
Patient history, findings from most recent colonoscopy, and disease severity and course should inform whether patients undergo colonoscopy after an episode of diverticulitis; colonoscopy is advised after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis but may be deferred if a recent (<1 year) high-quality colonoscopy has been performed.
After an acute episode of diverticulitis, colonoscopy should be delayed by 6 to 8 weeks or until complete resolution of the acute symptoms, whichever is longer; colonoscopy should be considered sooner if alarm symptoms are present.
In patients with a history of diverticulitis and chronic symptoms, imaging and lower endoscopy are advised to exclude ongoing inflammation; if there is no evidence of diverticulitis, visceral hypersensitivity should be considered and managed appropriately.
A clear liquid diet is advised during the acute phase of uncomplicated diverticulitis, with the diet advancing as symptoms improve.
Antibiotic treatment can be used selectively, rather than routinely, in immunocompetent patients with mild uncomplicated diverticulitis.
Antibiotic treatment is advised in patients with uncomplicated diverticulitis who have comorbidities or are frail, who present with refractory symptoms or vomiting, or who have a CRP level >140 mg/L or baseline white blood cell count >15 ´ 109 cells/L; antibiotic treatment is advised for patients with complicated diverticulitis or uncomplicated diverticulitis with a fluid collection or longer segment of inflammation on CT scan.
Immunocompromised patients are more likely to present with severe or complicated disease; these patients should have a low threshold for cross-sectional imaging, antibiotic treatment, and consultation with a colorectal surgeon.
A high-quality diet, normal body mass index, routine physical activity, and smoking cessation are advised to reduce the risk of diverticulitis recurrence;  patients with a history of diverticulitis should also avoid regular use (≥2 times per week) of NSAIDs (except aspirin prescribed for secondary prevention of cardiovascular disease).
Patients should understand that approximately 50% of the risk for diverticulitis is attributable to genetic factors.
Patients with a history of diverticulitis should not be treated with 5-aminosalicylic acid, probiotics, or rifaximin to prevent recurrent diverticulitis.
Patients should be educated that complicated diverticulitis is most often the first presentation of diverticulitis, and that the risk of complicated diverticulitis decreases with recurrences.
An elective segmental resection should not be advised based on the number of diverticulitis episodes.
A discussion of elective segmental resection for patients with a history of diverticulitis should be personalized to consider severity of disease, patient preferences, and values, as well as risks and benefits including quality of life; patients should understand that surgery reduces but does not eliminate diverticulitis risk and that chronic gastrointestinal symptoms do not always improve with surgery.


Peery AF, Shaukat A, Strate LL. AGA clinical practice update on medical management of colonic diverticulitis: expert review. Gastroenterology. Published online December 3, 2020. doi:10.1053/j.gastro.2020.09.059