Renal imaging in pyelonephritis.

BACKGROUND: Pyelonephritis accounts for a significant number of hospital admissions. It is unclear from existing literature whether all patients requiring admission to hospital should undergo renal imaging or if there is a subset that indicates clinical parameters for those who are more likely to have significant renal imaging abnormalities. METHOD AND
RESULTS: We undertook a retrospective study of 60 consecutive patients hospitalized with pyelonephritis, the majority of whom underwent renal ultrasound at the time of admission. Clinical data collected included age, sex, fever, serum creatinine, days for resolution of fever, premorbid conditions, and results of renal imaging. Sixteen per cent were found to have new and clinically significant abnormal findings; predominantly, urinary tract obstruction. We found no significant difference between the groups with abnormal and normal renal imaging in terms of any easily detectable clinical parameter such as change in serum creatinine, premorbid conditions, age, days for fever to resolve or white cell count on admission. We found a high proportion of Escherichia coli resistant to ampicillin (46%) but not to amoxycillin/clavulinic acid.
CONCLUSION: Although our study did not test whether immediate imaging is more advantageous than delaying imaging for those who fail to respond to treatment, our findings suggest that early imaging is a cost-effective part of management. On the basis of these data, we recommend renal imaging for all patients requiring hospital admission for pyelonephritis, and suggest that initial empirical therapy should include an intravenous dose of cephalosporin but not ampicillin.