First-time, mild diverticulitis: Antibiotics or watchful waiting?

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Don't jump to antibiotic Tx for mild, uncomplicated diverticulitis, a recent RCT says. Observation may be just as effective.


For mild, computed tomography-proven acute diverticulitis, consider observation only instead of antibiotic therapy.


B: Based on a single randomized controlled trial.

Daniels L, Ünlü Ç, de Korte N, et al, for the Dutch Diverticular Disease (3D) Collaborative Study Group. Randomized clinical trial of observational versus antibiotic treatment for a first episode of CT-proven uncomplicated acute diverticulitis. Br J Surg. 2017;104:52-61.1




A 58-year-old man presents to your office with a 2-day history of moderate (6/10) left lower quadrant pain, mild fever (none currently), 2 episodes of vomiting, no diarrhea, and no relief with over-the-counter medications. You suspect diverticulitis and obtain an abdominal computed tomography (CT) scan, which shows mild, uncomplicated (Hinchey stage 1a) diverticulitis.

How would you treat him?

Diverticulitis is common; about 200,000 people per year are admitted to the hospital because of diverticulitis in the United States.2,3 Health care providers typically treat diverticular disease with antibiotics and bowel rest.2,3 While severe forms of diverticulitis often require parenteral antibiotics and/or surgery, practitioners are increasingly managing the condition with oral antibiotics.4

One previous randomized control trial (RCT; N=623) found that antibiotic treatment (compared with no antibiotic treatment) for acute uncomplicated diverticulitis did not speed recovery or prevent complications (perforation or abscess formation) or recurrence at 12 months.5 The study’s strengths included limiting enrollment to people with CT-proven diverticulitis, using a good randomization and concealment process, and employing intention-to-treat analysis. The study was limited by a lack of a standardized antibiotic regimen across centers, previous diverticulitis diagnoses in 40% of patients, non-uniform follow-up processes to confirm anatomic resolution, and the lack of assessment to confirm resolution.5


RCT finds that watchful waiting is just as effective as antibiotic Tx

This newer study was a single-blind RCT that compared treatment with antibiotics to observation among 528 adult patients in the Netherlands. Patients were enrolled if they had CT-proven, primary, left-sided, uncomplicated acute diverticulitis (Hinchey stage 1a and 1b).1 (The Hinchey classification is based on radiologic findings, with 0 for clinical diverticulitis only, 1a for confined pericolic inflammation or phlegmon, and 1b for pericolic or mesocolic abscess.6) Exclusion criteria included suspicion of colonic cancer by CT or ultrasound (US), previous CT/US-proven diverticulitis, sepsis, pregnancy, or antibiotic use in the previous 4 weeks.1

Observational vs antibiotic treatment. Enrolled patients were randomized to receive IV administration of amoxicillin-clavulanate 1200 mg 4 times daily for at least 48 hours followed by 625 mg PO 3 times daily for 10 total days of antibiotic treatment (n=266) or to be observed (n=262). Computerized randomization, with a random varying block size and stratified by Hinchey classification and center, was performed, and allocation was concealed. The investigators were masked to the allocation until all analyses were completed.1

The primary outcome was the time to functional recovery (resumption of pre-illness work activities) during a 6-month follow-up period. Secondary outcomes included hospital readmission rate; complicated, ongoing, and recurrent diverticulitis; sigmoid resection; other nonsurgical intervention; antibiotic treatment adverse effects; and all-cause mortality.

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