Urinary tract infection in paediatrics: the role of diagnostic imaging

Abstract

Infection of the urinary tract (UTI) has several clinical subgroups, each requiring different degrees of investigation. The most severe, acute pyelonephritis, is characterized by ill health, anorexia, pyrexia (>38.5°C), an erythrocyte sedimentation rate greater than 20 mra/h or C-reactive protein greater than 10mg/l, pyuria, bacteruria and possible septicaemia. The child may well require hospitalization and parenteral antibiotics. The term cystitis is used to refer to children with lower urinary tract symptoms but without systemic illness who have more than 100000 bacteria per ml in the urine. They should be distinguished from children who are asymptomatic but nevertheless have positive urine cultures, i.e. asymptomatic bacteruria. This last group usually consists of girls over 5 years old and do not require much investigation. Clinically these three groups overlap to some extent, but nevertheless the presentation should be a guide to the choice of the appropriate imaging. Urinary tract infection is common: the imaging that children undergo is important in terms of resource utilization as well as discomfort and radiation exposure. A conscious effort must be made not to over-investigate the child or to overburden the radiology department, yet treatable disorders or potential long-term complications must be detected (Saxena et al, 1975; Asscher, 1980). A prospective study by Dickson (1979) found 3.1/ 1000 girls and 1.7/1000 boys presented annually with a first symptomatic UTI. The incidence of end-stage renal failure due to pyelonephritis in Europe in individuals under 40 years of age is 4–5 per million per year (Broyer et al, 1984).