Ultrasound for acute pyelonephritis: a systematic review and meta-analysis

There is little consensus regarding the indications and utility of urinary tract imaging and type of imaging to perform in patients presenting with acute pyelonephritis (APN).

The aims of this systematic review were to, among patients with APN, (i) identify the proportion of patients investigated with ultrasound (US), (ii) identify the proportion of abnormal US and (iii) identify the proportion of patients with a change in management resulting from abnormal US.

A comprehensive search covered two electronic databases (Medline and EMBASE), with selection of studies performed independently by two investigators. Inclusion criteria were English language APN diagnosis and quantification of patients assessed with US or abnormal US results. Quality appraisal used the Newcastle-Ottawa instrument.

There were 35 studies included. The proportion of patients assessed with US was reported in 16 manuscripts and ranged from 20% to 94%, with significant heterogeneity and publication bias. The proportion of abnormal US was reported in 31 manuscripts and ranged from 7% to 79%. The proportion of abnormal US leading to change in management was reported in five studies and ranged from 7% to 59%. There was marked heterogeneity among studies included in all three subgroups.

Patients with APN are commonly investigated with US, but only a small proportion have abnormalities and appear to be associated with changes in clinical management. The use of routine US for APN is therefore questioned. The identification of clinical variables for appropriate selection of patients to investigate with US requires further research.