Renal Abscesses Measuring 5 cm or Less: Outcome of Medical Treatment without Therapeutic Drainage

PURPOSE: Diagnosis and proper treatment of renal abscesses remains a challenge for physicians. We investigated the characteristics and comorbidity factors of renal abscesses measuring 5 cm or less and critically examined the effectiveness of conservative treatment. MATERIALS AND METHODS: Between February 2001 and March 2009 the records of 63 patients initially diagnosed at our hospital with renal or perirenal abscesses were retrospectively reviewed. In 63 patients with renal and perirenal abscesses, 51 abscesses measured 5 cm or less, and 49 abscesses were treated with intravenous antibiotics alone. RESULTS: Most patients were women (91.8%), and their mean age was 42.3 years. The mean size of renal abscesses was 3.6 cm. The most common predisposing condition was diabetes mellitus (DM) (46.9%). Common clinical features were fever (83.7%) and flank pain (53.1%). On urinalysis, 31 (64.6%) cases had positive bacterial cultures with Escherichia coli (50.0%) being the most common pathogen. All 49 patients were treated with broad-spectrum intravenous antibiotics alone. All patients showed complete clinical regression and resolution of the renal lesions shown by CT between 3 and 14 weeks. The average hospital stay was 15.3 days (range, 5-31 days). Significant predictors of a long hospital stay were age, abscess size, and DM. CONCLUSION: Medium-sized as well as small-sized renal abscesses were treated successfully with intravenous antibiotics alone. DM was a significant predictor of prolonged hospital stay. If therapeutic drainage is believed to involve considerable risk, then intravenous antimicrobial therapy may be a good alternative treatment.