Ambulatory treatment strategies for small abscess in colonic diverticulitis: A systematic review and qualitative synthesis

Abstract Purpose To evaluate the safety and effectiveness of oral antibiotic therapy for adults with diverticulitis complicated by a small diverticular abscess (pericolic abscess ≤ 4 cm) and assess whether oral treatment may represent a suitable alternative to intravenous antibiotics. Methods A systematic literature search of PubMed, Embase, Web of Science and Cochrane library was conducted through December 2025. Eligible studies included adults with small diverticular abscess treated with oral antibiotics, with or without comparator group receiving intravenous therapy. The primary outcome was treatment failure and included return visits for recurrent symptoms, changes in initial therapy, emergency surgeries, hospital readmission rates, need for percutaneous drainage. Secondary outcomes included treatment related adverse events as well as long-term outcomes such as recurrence, elective surgery, complications, and quality of life. Results Of 220 identified records, three observational studies met inclusion criteria, comprising a total of 384 patients. Only five patients had a clearly documented small abscess within the target size range. One additional outpatient had an abscess of unreported size. All five patients with a documented small abscess completed ambulatory oral treatment without acute treatment failure. However, broader cohort outcomes predominantly reflected patients without abscess, and no study directly compared oral with intravenous treatment in a defined small-abscess population. Conclusions This review demonstrates extremely limited data on ambulatory treatment in patients with small diverticular abscesses is and therefore highlights an important evidence gap. No statement can be made regarding the effectivity and safety in this patient group. Prospective studies comparing oral and IV-antibiotic treatment is needed for further clarification.