Vesicoureteral reflux (VUR) has been thought to be an important and pathological phenomenon leading to renal scarring and irreversible renal damage in children with urinary tract infection (UTI). This assumption has lead to practices where thousands of children with UTI undergo voiding cystourethrographies (VCUG).
However, the evidence of the causal relation between VUR and renal scarring is scanty and based mainly on experimental animal studies and historical observations on adults with a neurogenic bladder due to spinal cord injury.[1,2]
Recent meta-analyses have shown that the surgical treatment of VUR does not prevent renal scarring or impairment of renal function better than antimicrobial prophylaxis.[3]
Despite active evaluation and treatment of VUR, the prevalence of end-stage renal disease attributable to reflux nephropathy has not declined during last three decades.[4] Thus, it may even be that the identification and treatment of VUR is unimportant in most children.
The true prevalence of VUR in an unselected healthy population is uncertain, as it is unethical to perform VCUGs on healthy subjects and the often used figure of only about 1% is based on estimates.[5] Studies of siblings of children with VUR have shown 35-50% prevalence of VUR.[6]
In a large older study out of Germany in which a VCUG was performed on children with no urinary tract pathology, the prevalence of VUR was over 60% in infants and decreased with increasing age.[7] Since it would be impossible to perform a study of that kind today, we have to settle for indirect evidence of the prevalence of VUR in healthy children as in our present study.
We hypothesized that we could use the reliability of UTI diagnosis in a large patient series to find out an indirect estimate of the frequency of VUR among children without proven UTI.
Thus we made a large retrospective analysis of findings in VCUG and renal ultrasonography (US) in 2,036 children with suspected or proven UTI. Based on the urine cultures data, we classified the UTI diagnoses into five reliability classes and analyzed the prevalence of VUR in relation to the reliability of the UTI diagnoses.
In our cohort, some children without any reliable evidence of UTI had been examined by VCUG. They were sent to our hospital by their own doctor for VCUG even though the UTI diagnosis was based on wrong interpretation of the urine culture.
This fact made it possible to assess the prevalence of VUR in those with no reliable evidence of UTI. The overall prevalence of VUR was 34% and it was similar in all the patient groups irrespective of the diagnostic reliability of UTI and decreased with increasing age.
Contrary to the occurrence of VUR, we found that the frequency of significant US abnormalities increased as the diagnostic reliability improved, with an almost two-fold relative risk. This indicates that structural abnormalities identifiable with US are significant risk factors for UTI.
We conclude that the prevalence of VUR in children without proven UTI is considerably higher than the traditional estimates and thus VUR does not associate with UTI as strongly as reported earlier.
Vesicoureteral reflux seems to be a fairly common age-related phenomenon even in healthy children. This challenges the importance of a routine search for VUR by means of VCUG in every child with UTI.
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