Notice: An addendum was added to this report in March 2022. The addendum is located at the end of the main report, before the appendixes.

Main Points

• Computed tomography (CT) diagnosis and clinical sequelae
  • CT accurately diagnoses acute diverticulitis (moderate strength of evidence [SoE]) and may increase appropriate management versus clinical diagnosis (low SoE). Due to sparse data, there is insufficient evidence about CT accuracy to stage acute diverticulitis. Misdiagnoses on CT may not increase the risk of poor clinical outcomes (low SoE). The significance of incidental findings is unclear (low SoE).
• Treatment of patients with acute diverticulitis
  • Outpatient management: For patients with uncomplicated acute diverticulitis, outpatient management may be as effective as inpatient care (low SoE), but there is insufficient evidence regarding important clinical outcomes, including treatment failure, mortality, or emergency surgery.
  • Antibiotic treatment: For patients with uncomplicated diverticulitis, antibiotic treatment may not affect pain symptoms, length of hospital stay, recurrence risk, quality of life, or need for surgery compared to no antibiotic treatment (low SoE). For patients who do receive antibiotics, the evidence is insufficient to guide choice of antibiotic regimen.
  • Interventional radiology: The evidence is insufficient regarding the benefits or harms of percutaneous drainage for patients with complicated acute diverticulitis.
• Colonoscopy following an episode of acute diverticulitis
  • There is low SoE that patients with recent diverticulitis (within 6–12 months) may be more likely to have colorectal cancer (CRC) than the general population.
  • With low SoE, among patients with recent diverticulitis, those who undergo colonoscopy may, ultimately, have similar rates of CRC diagnoses as those who did not; however, no studies evaluated comparative risks of CRC death.
  • Patients who are 50 or older or who had complicated diverticulitis (with abscess, peritonitis, etc.) are at increased risk of having CRC (moderate SoE), advanced colonic neoplasia (high SoE), or advanced adenoma (low SoE) on colonoscopy.
  • Colonoscopies conducted within 1.5 to 12 months after acute diverticulitis rarely have complications or incomplete tests (high SoE).
• Nonsurgical interventions to prevent recurrent diverticulitis
  • 5-aminosalicylic acid (5-ASA) offers no benefit to patients to reduce the risk of recurrence of diverticulitis (high SoE). Evidence for other interventions is insufficient.
• Elective surgery to prevent recurrent diverticulitis
  • For patients with prior complicated or smoldering/frequently recurrent (after uncomplicated) diverticulitis, elective surgery reduces the risk of recurrent diverticulitis (high SoE). However, there is no evidence regarding which patients would benefit most from elective surgery. With low to moderate SoE, serious surgical complications included 30-day mortality (0.7%), 30-day readmission (7.3%), and reoperation (5.5%).

Structured Abstract

Background. There remain uncertainties about the effectiveness and harms of various nonsurgical treatment options for acute diverticulitis, clinical consequences of diagnostic imaging, detection strategies for colorectal cancer (CRC) in patients with recent diverticulitis, and preventive options for long-term recurrence.

Methods. We searched Medline^®, the Cochrane databases, Embase^®, CINAHL^®, and ClinicalTrials.gov from 1990 through June 1, 2020. We included existing systematic reviews (SRs) of computed tomography (CT) test accuracy, randomized controlled trials, adequately adjusted nonrandomized comparative studies for all topics, and larger single-group studies that addressed specific questions.

Results. We included 77 primary studies and 2 SRs. With moderate strength of evidence (SoE), CT has high sensitivity (94%) and specificity (99%) to diagnose acute diverticulitis. There is low SoE that CT imaging leads to appropriate management decisions and that misdiagnoses on CT do not result in poor clinical outcomes. Incidental findings on CT may be common (low SoE), but their clinical significance is unclear. There is insufficient evidence about CT test accuracy to stage acute diverticulitis. For patients with uncomplicated acute diverticulitis, there is low SoE that initial outpatient or inpatient management have similar risks of recurrence or elective surgery, but insufficient evidence regarding risk of treatment failure and other outcomes. For patients with uncomplicated acute diverticulitis, there is low SoE that antibiotic treatment does not affect clinically important outcomes. There is insufficient evidence regarding percutaneous drainage to manage complicated acute diverticulitis. There is low SoE that patients with recent acute diverticulitis may be at increased risk of CRC compared with the general population, but that those who undergo colonoscopy soon after acute diverticulitis may ultimately have similar rates of CRC as those who do not. Patients 50 years and older may be at increased risk of CRC (moderate SoE) or premalignant lesions (low to high SoE) compared with younger patients. Colonoscopy after acute diverticulitis rarely results in complications or incomplete procedures (high SoE). The risk of recurrence is not reduced by 5-aminosalicylic acid (5-ASA) (high SoE). The evidence regarding other nonsurgical interventions to prevent recurrence is insufficient. In patients with prior complicated or smoldering/frequently recurrent (after uncomplicated) diverticulitis, elective surgery reduces the risk of diverticulitis recurrence (high SoE), but there is no evidence regarding which patients may benefit most from surgery.

Conclusion. Important questions about which interventions should be used for which patients remain either unanswered or answered with only low SoE. New high-quality research is needed.

Journal Citations

Balk EM, Adam GP, Bhuma MR, et al. Diagnostic imaging and medical management of acute left-sided colonic diverticulitis: a systematic review. Ann Intern Med. 2022 Jan 18 [Epub ahead of print]. doi: 10.7326/M21-1645. PMID: 35038271.

Balk EM, Adam GP, Cao W, et al. Evaluation and management after acute left-sided colonic diverticulitis: a systematic review. Ann Intern Med. 2022 Jan 18 [Epub ahead of print]. doi: 10.7326/M21-1646. PMID: 35038269.

Citation

Balk EM, Adam GP, Cao W, Danko K, Bhuma MR, Mehta S, Saldanha IJ, Beland MD, Shah N. Management of Colonic Diverticulitis. Comparative Effectiveness Review No. 233. (Prepared by the Brown Evidence-based Practice Center under Contract No. 290-2015- 00002-I.) AHRQ Publication No. 20(21)-EHC025. Rockville, MD: Agency for Healthcare Research and Quality; October 2020. DOI: 10.23970/AHRQEPCCER233. Posted final reports are located on the Effective Health Care Program search page.