Antibiotics alone instead of percutaneous drainage as initial treatment of large diverticular abscess

Background There are limited data assessing the effectiveness of antibiotics as sole initial therapy in patients with large diverticular abscess. The aim of our study was to compare outcomes of selected patients treated with initial antibiotics alone versus percutaneous drainage. Methods All patients with diverticular abscess >= 3 cm in diameter treated in our institution in 1994-2012 with percutaneous drainage or antibiotics alone followed by surgery were identified from an institutional diverticular disease database. Groups were compared based on patient and disease characteristics, treatment failures and postoperative outcomes. Results Thirty-two patients were treated with antibiotics alone because of either technically impossible percutaneous drainage (n = 15) or surgeon preference (n = 17) while 114 underwent percutaneous drainage. Failure of initial treatment required urgent surgery in 8 patients with persistent symptoms during treatment with antibiotics alone (25 %) and in 21 patients (18 %) after initial percutaneous drainage (p = 0.21). Reasons for urgent surgery after percutaneous drainage were persistent symptoms (n = 16), technical failure of percutaneous drainage (n = 4) and small bowel injury (n = 1). Patients treated with antibiotics had a significantly smaller abscess diameter (5.9 vs. 7.1 cm, p = 0.001) and shorter interval from initial treatment to sigmoidectomy (mean 50 vs. 80 days, p = 0.02). The Charlson comorbidity index, initial treatment failure rates, postoperative mortality, overall morbidity, length of hospital stay during treatments, and overall and permanent stoma rates were comparable in the two groups. Postoperative complications following antibiotics alone were significantly less severe than after percutaneous drainage based on the Clavien-Dindo classification (p = 0.04). Conclusions Selected patients with diverticular abscess can be initially treated with antibiotics without adverse consequences on their outcomes.