Diverticulitis Updates

Acute diverticulitis is increasingly managed as an inflammatory illness, not an automatic antibiotic diagnosis. CT abdomen and pelvis with IV contrast remains the reference imaging test for complicated disease, but selected well-appearing patients with suspected uncomplicated diverticulitis may not need CT or antibiotics.

Diverticulitis Evaluation and Imaging

• Clinical diagnosis limits: History and exam alone are unreliable, correctly identifying diverticulitis in only about 25% to 75% of cases, so the real bedside task is separating uncomplicated disease from occult complication.
• Helpful bedside findings: Left lower quadrant tenderness is the strongest classic exam clue, with a positive likelihood ratio around 10, while peritonitis should immediately raise concern for perforation or other complicated disease.
• Inflammatory marker signal: CRP is more useful than the white count for risk stratification; a CRP above 50 mg/L strongly points toward complicated diverticulitis, while isolated labs perform poorly on their own.
• CT as reference test: CT abdomen and pelvis with IV contrast is the go-to study, with sensitivity above 94% and specificity near 99% for both uncomplicated and complicated diverticulitis.
• When imaging may wait: A well-appearing, immunocompetent patient with left lower quadrant pain that feels like a prior uncomplicated episode may not need immediate CT. We get into the patient-selection nuance in the episode.

Antibiotics, Disposition, and Follow-up

• Inflammation over infection: Uncomplicated diverticulitis often behaves as a primarily inflammatory process, and multiple randomized trials plus meta-analysis found no clear outcome advantage to routine antibiotics in selected patients.
• Who still needs antibiotics: Complicated diverticulitis, microperforation, sepsis, immunocompromise, or major comorbidity still push management toward antibiotics and closer observation rather than minimalist outpatient care.
• Abscess size matters: Small abscesses under 3 to 4 cm often improve with antibiotics alone, while larger collections or failures to improve are the group where drainage enters the conversation.
• Admission versus discharge: Uncomplicated diverticulitis can usually go home with close follow-up if the patient tolerates oral intake and remains stable; complicated disease needs admission and surgical involvement.
• Colonoscopy after recovery: After symptoms resolve, complicated diverticulitis warrants colonoscopy because up to 10% of cases have an underlying colorectal malignancy. That follow-up distinction is worth hearing in the chapter.
• Recurrence trajectory: Recurrence after a first episode is modest at roughly 20% by 10 years, but after a second episode the 10-year recurrence risk rises to about 50%, which changes follow-up conversations.

References:

1. Long B, Werner J, Gottlieb M. Emergency medicine updates: Acute diverticulitis. Am J Emerg Med. 2024 Feb;76:1-6. Epub 2023 Nov 5. PMID: 37956503.
2. Chabok A, Påhlman L, Hjern F, Haapaniemi S, Smedh K; AVOD Study Group. Randomized clinical trial of antibiotics in acute uncomplicated diverticulitis. Br J Surg. 2012 Apr;99(4):532-9. Epub 2012 Jan 30. PMID: 22290281.
3. Hammond NA, Nikolaidis P, Miller FH. Left lower-quadrant pain: guidelines from the American College of Radiology appropriateness criteria. Am Fam Physician. 2010 Oct 1;82(7):766-70. PMID: 20879699.
4. Sartelli, et al. 2020 update of the WSES guidelines for the management of acute colonic diverticulitis in the emergency setting. World J Emerg Surg. 2020 May 7;15(1):32. PMID: 32381121
5. Hall J, et al.; Prepared on behalf of the Clinical Practice Guidelines Committee of the American Society of Colon and Rectal Surgeons. The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Left-Sided Colonic Diverticulitis. Dis Colon Rectum. 2020 Jun;63(6):728-747. PMID: 32384404.
6. Peery AF, Shaukat A, Strate LL. AGA Clinical Practice Update on Medical Management of Colonic Diverticulitis: Expert Review. Gastroenterology. 2021 Feb;160(3):906-911.e1. doi: 10.1053/j.gastro.2020.09.059. Epub 2020 Dec 3. PMID: 33279517
7. Qaseem A, et al.; Clinical Guidelines Committee of the American College of Physicians*; Crandall CJ, et al.; Clinical Guidelines Committee of the American College of Physicians. Diagnosis and Management of Acute Left-Sided Colonic Diverticulitis: A Clinical Guideline From the American College of Physicians. Ann Intern Med. 2022 Mar;175(3):399-415. PMID: 35038273.
8. Expert Panel on Gastrointestinal Imaging; Weinstein S, et al. ACR Appropriateness Criteria® Left Lower Quadrant Pain: 2023 Update. J Am Coll Radiol. 2023 Nov;20(11S):S471-S480. PMID: 38040465.
9. Laméris W, et al. A clinical decision rule to establish the diagnosis of acute diverticulitis at the emergency department. Dis Colon Rectum. 2010 Jun;53(6):896-904. doi: 10.1007/DCR.0b013e3181d98d86. PMID: 20485003.
10. Bolkenstein HE, et al. Risk factors for complicated diverticulitis: systematic review and meta-analysis. Int J Colorectal Dis. 2017 Oct;32(10):1375-1383. doi: 10.1007/s00384-017-2872-y. Epub 2017 Aug 10. PMID: 28799055
11. Seta T, et al. Efficacy of antimicrobial therapy in patients with uncomplicated acute colonic diverticulitis: an updated systematic review and meta-analysis. Eur J Gastroenterol Hepatol. 2023 Oct 1;35(10):1097-1106. Epub 2023 Jul 28. PMID: 37577799.