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Diverting from Antibiotics for Diverticulitis: Disastrous or Opportune?


A 40 y.o. male presents with two days of gradually worsening cramping left abdominal pain, chills, nausea, and yellow watery diarrhea.

  • PMH: Recurrent Diverticulitis, HTN, COPD, Non-Hodgkins Lymphoma status post chemo/radiation

  • 3 years ago: Acute distal descending colonic diverticulitis with microperforation, complicated by sepsis from E. coli bacteremia, candida glabrata fungemia, and c. diff. colitis

  • 1 year ago: Perforation of proximal descending colon diverticulitis

  • 7 months ago: Colonic diverticulosis with mild wall thickening, without stranding

  • PSH: No prior abdominal surgeries or resections, despite recurrent diverticulitis, due to patient’s preference and general surgery consultation​

  • BP: 129/87, HR: 110, Temp: 36.2 °C (97.2 °F), RR: 16, SpO2: 97% |

  • Abdominal Exam: normoactive bowel sounds, distended and firm abdomen, LLQ and LUQ tenderness, voluntary guarding.

  • WBC: 13.8

  • CT Abdomen: Acute colonic diverticulitis, with marked stranding in the left lower quadrant at the sigmoid colon with tiny foci of extraluminal gas in keeping with microperforation. No abscess formation.

Clinical Question

Does acute uncomplicated diverticulitis require treatment with antibiotics?

Summary of Evidence

American Gastroenterological Association Institute Current Guidelines recommends selective use of antibiotics, rather than routine, for uncomplicated acute diverticulitis.(1)

  • Supported by a “low quality of current evidence.”(2)

  • No clarification if this includes recurrent episodes of diverticulitis nor criteria of what is “uncomplicated”

The AVOD randomized control trial demonstrated that antibiotic use in uncomplicated diverticulitis does not accelerate recovery, prevent complications in 6 months, nor decrease recurrence of diverticulitis within 1 year.(3)

  • 623 patients with CT scan of acute uncomplicated left-sided diverticulitis were randomized into two groups: 314 patients treated with antibiotics and 309 without antibiotics across 10 centers from Sweden and 1 in Iceland from 2003-2010

  • The median age of participants was 58, 403/623 (64.67%) participants were female, 247/623 (39.6%) had previous episodes of diverticulitis

  • Inclusion criteria: age of 18 or older, presentation of acute lower abdominal pain with tenderness, body temp of 38 C at admission or 12 hours prior to admission, elevated WBC and CRP (at least elevated WBC), and CT scan of left-sided diverticulitis

  • Age, sex, BMI, co-morbidities, body temp, WBC and CRP on admission were similar between the group treated with antibiotics and the group treated without antibiotics

  • Excluded were those with complicated diverticulitis on CT, including abscess, fistula, or free air in abdomen or pelvis, high fever (no specific value), affected general condition, peritonitis, sepsis, ongoing antibiotic therapy, and receiving immunosuppressive therapy

  • Centers varied in antibiotic selection: 2nd/3rd generation cephalosporin + metronidazole, or carbapenem, or piperacillin/tazobactam. The total duration of antibiotics was at least 7 days

  • For both groups, the median hospital stay was 3 days.

  • There was no significant difference in complications between both groups after 6-8 weeks; complications included perforation and abscess formation.

  • Hospital readmission due to recurrence at 1-year follow-up was 16 percent in both groups

The DIABOLO randomized control trial demonstrated treatment without antibiotics did not prolong time to recovery and did not increase complications such as adverse events or hospital readmission within 6 months. (4)

  • 522 patients with CT scan showing a primary episode of left-sided acute uncomplicated diverticulitis were randomized into two groups: 266 patients treated with antibiotics and 262 treated without antibiotics across 22 clinical sites in Netherlands from 2010-2012

  • The participants mean age ranged from 56.3-57.4, had similar male to female ratio included in the study, mean BMI 26.4-27.2, and mean WBC 12.5.

  • Inclusion criteria were first episode of left‐sided, mild, uncomplicated acute diverticulitis, confirmed by CT scan within 24 hours. Uncomplicated diverticulitis was Hinchey stages 1a–b (abscess size up to 5 cm)

  • Excluded were those with previous diverticulitis proven by CT or Ultrasound, IBD, Ultrasound or CT suspicion of colon cancer, modified Hinchey classification stages (2-4), immunocompromised, bacteremia or sepsis, and antibiotics used in last 4 weeks

  • Antibiotic treatment remained consistent among all sites; amoxicillin–clavulanic acid for 10 day course

  • The median time to recovery was 14 days without antibiotics and 12 days with antibiotics.

  • No significant differences between groups within 6 months for secondary outcomes, including complicated diverticulitis, ongoing diverticulitis, recurrent diverticulitis, sigmoid resection, hospital readmission, adverse events, and mortality

Further research is required that includes patients with “complicated” diverticulitis, recurrent diverticulitis, and consistent antibiotics amongst treatment groups

  • Complicated diverticulitis lacks a concrete definition in both studies and is not consistent with a standardized classification scheme.

  • Only the AVOD study included recurrent diverticulitis episodes but did not elaborate on if the prior episodes were benign or had complications/surgery implications.

  • Though varying antibiotic treatments have been utilized in the studies, a standardized treatment group with consistent antibiotic choice and duration would make the studies higher quality and more applicable.

  • The patient characteristics did not include ethnicity and the average age of participants was 56-58. Therefore, it may not be completely accurate to generalize these findings to younger patients and those of different ethnicities, especially if these two groups may present differently or have varying risk of severe complications.


  • The current patient has recurrent diverticulitis with microperforation and requires antibiotics due to concern for sepsis given his tachycardia and elevated WBC of 13.8.

  • Existing research is not able to provide a gold standard classification of uncomplicated diverticulitis that is safe to treat without antibiotics.

  • Though his CT scan demonstrates radiological evidence of “uncomplicated” diverticulitis due to lack of perforation, he has suffered from severe complications in the past from recurrent diverticulitis, which makes his case complicated.

  • Future research should focus on developing a risk stratification score or specific criterion to aid clinicians in stratifying which patients to treat with or without antibiotics that incorporates recurrence of episodes, sepsis risk factors, universal CT scan classification scheme, and history of complications.

  • I suggest treatment with antibiotics for all patients who have a CT scan demonstrating acute uncomplicated diverticulitis, despite the guidelines suggesting selective use, because no risk stratification for potential future complications exists, unless clinicians can guarantee proper follow-up and the patient has access to healthcare resources promptly if complications do occur.


1 N. Stollman, W. Smalley, I. Hirano, et al. American Gastroenterological Association Institute guideline on the management of acute diverticulitis. Gastroenterology, 149 (2015), pp. 1944-1949.

2 L.L. Strate, A.F. Peery, I. Neumann American Gastroenterological Association institute technical review on the management of acute diverticulitis. Gastroenterology, 149 (2015), pp. 1950-1976

3 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; 99: 532–539.

4 Daniels L, Ünlü Ç, de Korte N, et al; Dutch Diverticular Disease Collaborative Study Group. Randomized clinical trial of observational vs antibiotic treatment for a first episode of CT-proven uncomplicated acute diverticulitis. Br J Surg. 2017; 104(1):52-61.