Guidelines On Diverticulitis With Links To Additional Resources

In addition to the resource below please review

  • Hinchey classification of acute diverticulitis from Radiopaedia
    Last revised by Dr Daniel J Bell◉ on 01 Apr 2021

    • Classification

      • stage 0:
        • clinical: mild clinical diverticulitis
        • CT finding: diverticula with colonic wall thickening
      • stage Ia:
        • clinical: confined pericolic inflammation or phlegmon
        • CT finding: pericolic soft tissue changes
      • stage Ib:
        • clinical: pericolic or mesocolic abscess
        • CT finding: Ia changes and pericolic or mesocolic abscess
      • stage II:
        • clinical: pelvic, distant intra-abdominal or retroperitoneal abscess
        • CT finding: Ia changes and distant abscess, usually deep pelvic
      • stage III:
        • clinical: generalized purulent peritonitis
        • CT finding: localized or generalized ascites, pneumoperitoneum, peritoneal thickening
      • stage IV: 
        • clinical: generalized fecal peritonitis
        • CT finding: same as stage III

      Clinical use

      In general, abscesses in stage Ib and II may be drained by interventional radiology, and stage III and IV disease is managed with emergent surgery

  • Diagnostic accuracy of low-dose CT compared with abdominal radiography in non-traumatic acute abdominal pain: prospective study and systematic review [PubMed Abstract]. Eur Radiol. 2016 Jun;26(6):1766-74.
    • “Conclusions: Based on the current study and available evidence, low-dose CT has higher diagnostic accuracy than abdominal radiography and it should, where logistically possible, replace abdominal radiography in the workup of adult patients with acute non-traumatic abdominal pain.”
    • “Key points: • Low-dose CT has a higher diagnostic accuracy than radiography. • A systematic review shows that CT has better diagnostic accuracy than radiography. • Radiography has no place in the workup of acute non-traumatic abdominal pain.”

In this post, I link to and excerpt  from The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Left-Sided Colonic Diverticulitis [PubMed Abstract] [Full-Text HTML] {Full-Text PDF]. Dis Colon Rectum. 2020 Jun;63(6):728-747.

All that follows is from the above resource.

As our understanding of diverticulitis has evolved, so have recommendations for the clinical management of these patients. Patients with diverticular disease are increasingly being treated as outpatients. Rates of admission to the hospital after emergency department evaluation for diverticulitis dropped from 58.0% in 2006 to 47.1% in 2013.10 In addition, fewer patients are undergoing emergency bowel surgery; the rate of patients undergoing an intestinal operation per emergency department visit for diverticulitis decreased from 7278 of 100,000 to 4827 of 100,000 between 2006 and 2013.10 Concomitantly, there has been an increase in the use of elective and laparoscopic surgery in the management of diverticulitis.11

This publication summarizes the changing treatment paradigm for patients with left-sided diverticulitis. Although diverticular disease can affect any segment of the large intestine, we will focus on left-sided disease.


1. The initial evaluation of a patient with suspected acute diverticulitis should include a problem-specific history and physical examination and appropriate laboratory evaluation. Grade of Recommendation: Strong recommendation based on low-quality evidence, 1C.

Classic findings related to sigmoid diverticulitis include left lower quadrant pain, fever, and leukocytosis. Fecaluria, pneumaturia, or pyuria are concerning for possible colovesical fistula, and stool per vagina is concerning for possible colovaginal fistula.

Physical examination, complete blood count, urinalysis, and abdominal radiographs can be helpful in refining the differential diagnosis. Other diagnoses to consider when patients present with suspected diverticulitis may include constipation, irritable bowel syndrome, appendicitis, IBD, neoplasia, kidney stones, urinary tract infection, bowel obstruction, and gynecologic disorders.

C-reactive protein has been assessed as a marker of complicated diverticulitis in multiple case series in an attempt to identify a biomarker that can discriminate patients who have complicated disease. Many of the series are small and the suggested cutoff values vary.18–22 However, in one retrospective study of 350 patients presenting with their first episode of diverticulitis, CRP >150 mg/L significantly discriminated acute uncomplicated from complicated diverticulitis and the combination of CRP >150 mg/L and free fluid on CT scan was associated with a significantly greater risk of mortality.23

2. CT scan of the abdomen and pelvis is the most appropriate initial imaging modality in the assessment of suspected diverticulitis. Grade of Recommendation: Strong recommendation based on moderate-quality evidence, 1B.

Computed tomography imaging has become a standard tool to diagnose diverticulitis, assess disease severity, and help devise a treatment plan. Low-dose CT, even without oral or intravenous contrast media, is highly sensitive and specific (95% for each) for diagnosing acute abdominal complaints including diverticulitis as well as other etiologies that can mimic the disease.25 Computed tomography findings associated with diverticulitis may include colonic wall thickening, fat stranding, abscess, fistula, and extraluminal gas and fluid and can stratify patients according to Hinchey classification.26 The utility of CT imaging goes beyond the accurate diagnosis of diverticulitis; the grade of severity on CT correlates with the risk of failure of nonoperative management in the short term and with long-term complications such as recurrence, the persistence of symptoms, and the development of colonic stricture and fistula.27–29

3. Ultrasound and MRI can be useful alternatives in the initial evaluation of a patient with suspected acute diverticulitis when CT imaging is not available or is contraindicated. Grade of Recommendation: Strong recommendation based on low-quality evidence, 1C.

Ultrasound and MRI may be useful in patients with a contrast allergy where CT can be challenging or in pregnant patients. Ultrasound can be particularly useful to rule out other causes of pelvic pain that can mimic diverticulitis when the diagnosis is unclear, especially in women.30 However, ultrasound can miss complicated diverticulitis and thus should not typically be the only imaging modality utilized if this is suspected.31 Although ultrasound evaluation is included as a diagnostic option in the practice guidelines of several societies, ultrasound is user dependent and its utility in obese patients may be limited.32,33 Where available, MRI can also be useful in patients in whom CT is contraindicated and may be better than CT at differentiating neoplasia from diverticulitis.34


1. Selected patients with uncomplicated diverticulitis can be treated without antibiotics. Grade of Recommendation: Strong recommendation based on high-quality evidence, 1A.

Until recently, the routine use of antibiotics has been the primary treatment for patients presenting with acute diverticulitis. The generally accepted pathophysiologic mechanism of diverticulitis has been challenged because new evidence suggests that diverticulitis is primarily an inflammatory process that can result in micro-perforation rather than a complication of micro-perforation itself.4

A Cochrane review also found no significant differences in outcomes between patients with uncomplicated diverticulitis treated with or without antibiotics.41 These studies suggest that a proportion of patients with uncomplicated diverticulitis can be treated without antibiotics. It is important to emphasize that nearly all of the patients included in these studies were relatively healthy and had early-stage diverticular disease (Hinchey I and Ia)*. Some investigators have also demonstrated that an antibiotic-free approach can be successful in the outpatient setting.42

A number of other systematic reviews and meta-analyses have also supported this approach.37,43–46

*Please see Hinchey classification of acute diverticulitis from Radiopaedia
Last revised by Dr Daniel J Bell◉ on 01 Apr 2021

2. Nonoperative treatment of diverticulitis may include antibiotics. Grade of Recommendation: Strong recommendation based on low-quality evidence, 1C.

Before the 2 randomized trials questioning the benefit of antibiotics in uncomplicated diverticulitis, antibiotic therapy was and still is a standard component of the armamentarium used to treat all stages of this disease.1 The use of antibiotics continues to be appropriate for higher-risk patients with significant comorbidities, signs of systemic infection, or immunosuppression. Both of the randomized trials supporting avoidance of antibiotics included only patients with early-stage disease (Hinchey I and Ia).35,36 Therefore, the use of antibiotics continues to be appropriate in all other stages of the disease.

3. Image-guided percutaneous drainage is usually recommended for stable patients with abscesses >3 cm in size. Grade of Recommendation: Strong recommendation based on moderate-quality evidence, 1B.

Complicated diverticulitis with abscess formation occurs in 15% to 40% of patients who present with acute sigmoid diverticulitis. Overall, nonoperative treatment with either antibiotics alone or in combination with percutaneous drainage is successful in up to 80% of cases.50–52 Treatment failure is typically defined as requiring surgery, developing worsening sepsis, or having a recurrent abscess within 30 days.53

Antibiotic treatment alone for abscesses smaller than 3 cm is typically successful and, in stable patients, treatment can usually be administered in the outpatient setting. When this approach fails, percutaneous drainage should be considered, particularly in patients with larger abscesses (>3 cm) where antibiotics alone have a much higher failure rate (up to 34%).53,54 There is no correlation between abscess size and failure of percutaneous drainage.53,55,56 Although recurrence after antibiotic treatment of diverticular abscesses ranges from 25% to 60% of patients, recurrence after percutaneous drainage is significantly lower (15%–25%).50,57,58 Patients who do not have a safe access window for percutaneous drainage or who do not respond to medical treatment including percutaneous drainage should typically be considered for surgery. Laparoscopic abscess drainage rather than surgical resection can be considered in certain cases.59

4. Tobacco cessation, reduced meat intake, physical activity and weight loss are recommended interventions to potentially reduce the risk of diverticulitis. Grade of Recommendation: Strong recommendation based on low-quality evidence, 1C.

The progression of normal colonic architecture to diverticulosis and subsequent diverticulitis is not well understood but is multifactorial and involves diet, genetics, lifestyle, and, possibly, the microbiome.60,61

A variety of agents have been studied to try to prevent recurrent attacks of diverticulitis. Although a high-fiber diet is associated with a lower risk of having a first episode of acute diverticulitis, the utility of fiber supplements in secondary prevention of diverticulitis is unclear.64–66

5. Mesalamine, rifaximin, and probiotics are not typically recommended to reduce the risk of diverticulitis recurrence but may be effective in reducing chronic symptoms. Grade of Recommendation: Weak recommendation based on moderate-quality evidence, 2B.

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