Urinary tract infection (UTI) is a common and important clinical problem in childhood. Upper urinary tract infections (ie, acute pyelonephritis) may lead to renal scarring, hypertension, and end-stage renal disease. Although children with pyelonephritis tend to present with fever, it is often difficult on clinical grounds to distinguish cystitis from pyelonephritis, particularly in young children (those younger than two years) . Thus, we have defined UTI broadly here without attempting to distinguish cystitis from pyelonephritis. Acute cystitis in older children is discussed separately. (See "Acute cystitis in children older than two years and adolescents".)
The presence of risk factors for UTI and renal scarring in a child presenting with fever and/or urinary symptoms is helpful in guiding diagnostic testing and management. The epidemiology and risk factors for UTI and renal scarring in children will be reviewed here. Clinical features, diagnosis, and management of UTI, and UTI in newborns (younger than one month of age) are discussed separately. (See "Clinical features and diagnosis of urinary tract infections in infants and children older than one month" and "Acute management, imaging, and prognosis of urinary tract infections in infants and children older than one month" and "Long-term management and prevention of urinary tract infections in children" and "Urinary tract infections in newborns".)
Knowledge of the epidemiology of urinary tract infection (UTI) is important in the evaluation of a child with suspected UTI. (See "Clinical features and diagnosis of urinary tract infections in infants and children older than one month", section on 'Laboratory evaluation'.)
Prevalence — Awareness of the prevalence of UTI in various subgroups of children enables the clinician to grossly estimate the probability of infection in the patient (ie, the pretest probability) (table 1).
In young children with fever — The prevalence of UTI in children <2 years presenting with fever has been the subject of several large prospective studies and a meta-analysis [2-4]. Important points that emerged from these studies include: