From the Guidelines

Antibiotic treatment is not necessary for Hinchey stage 1B diverticulitis.

The DIABOLO trial 1 found that observational treatment without antibiotics did not prolong recovery and could be considered appropriate in patients with uncomplicated diverticulitis, including those with Hinchey stage 1B.
The WSES guidelines 1 recommend not prescribing antibiotic therapy in immunocompetent patients with uncomplicated acute diverticulitis, including those with Hinchey stage 1B.
A systematic review and meta-analysis 1 found that treatment of acute uncomplicated diverticulitis without antibiotics might be feasible with outcomes that are comparable to antibiotic treatment.
The European Society of Clinical Microbiology and Infectious Diseases guidelines 1 suggest that routine administration of antibiotics to patients with uncomplicated diverticulitis does not lead to better outcomes than withholding antibiotics.
However, high-risk patients, such as immunocompromised patients, elderly patients, and those with extensive comorbidities, may require antibiotic therapy 1.

No antibiotics are needed for Hinchey stage 1B diverticulitis in immunocompetent patients without signs of systemic inflammation 1.
Oral administration of antibiotics may be equally as effective as intravenous administration 1.
Antibiotic therapy should be reserved for complicated diverticulitis or high-risk patients 1.

From the Research

The use of antibiotics for Hinchey stage 1B diverticulitis is a topic of debate, with some studies suggesting that antibiotics may not be necessary for uncomplicated cases 2, 3, 4, 5.
A study published in 2021 found that antibiotic treatment did not reduce the length of hospital stay for patients with uncomplicated diverticulitis, and that placebo treatment was not inferior to antibiotic treatment 3.
A systematic review and meta-analysis published in 2024 found that patients with uncomplicated acute diverticulitis (Hinchey grade 1a) who did not receive antibiotics had a lower disease recurrence rate and shorter length of hospital stay compared to those who received antibiotics 4.
Another study published in 2024 found that first-line management of uncomplicated diverticulitis (Hinchey classification 0 and Ia) now constitutes a clear-liquid diet along with bowel rest for resolution of symptoms, rather than antibiotic treatment 5.
A retrospective study published in 2022 found that patients with uncomplicated acute diverticulitis (modified Hinchey 1a) could be safely treated as outpatients if they had poor physical examination findings, and that follow-up with outpatient oral antibiotic therapy might be reliable, although prospective studies with larger numbers of patients are needed 6.

Antibiotics may not be necessary for uncomplicated Hinchey stage 1B diverticulitis 2, 3, 4, 5.
Non-antibiotic management, such as a clear-liquid diet and bowel rest, may be effective for uncomplicated cases 5.
Outpatient treatment may be safe and reliable for patients with uncomplicated acute diverticulitis (modified Hinchey 1a) who have poor physical examination findings 6.