Permanent renal parenchymal defects after febrile UTI are closely associated with vesicoureteric reflux

This study from Italy investigated the association of vesicoureteral reflux (VUR) and renal scarring.

It has been shown that children with a febrile urinary tract infection (UTI) and no VUR may have evidence of renal defects when imaged with scintigraphic studies. Therefore, it has been postulated that VUR is a weak predictor of renal defects.

The group employed isotopic cystography (IC) for diagnosis of VUR in children with febrile UTIs. Dimercaptosuccinic acid renal scintigraphy was performed 6 months after cure of the last UTI. They defined renal defects by the observation of focal defects of radionuclide uptake and/or by a split renal function <43%. The study included 206 children with primary VUR and 77 without VUR. Among the patients with and without VUR, respectively, renal defects were found in 40 and 6% (p=0.0001), focal uptake defects in 33 and 5% (p=0.0001) and split renal function <43% in 26 and 5% (p=0.0001). From this data the group concluded that renal defects in children with febrile UTI are closely associated with VUR. They state that the possibility that a child will have permanent renal defects can reasonably be ruled out on the basis of the absence of VUR by IC.

The major criticism I have is that we need a baseline to come to such a conclusion. It is a known fact that some children with VUR have an abnormal renal scan without ever having a UTI. This most likely represents dysplasia and not scarring. I would be wary to conclude that if a child has pyelonephritis without VUR, that child is free from the possible development of renal scarring. Scarring is caused by infection and inflammation, so why would a pyelonephritis without reflux scar different from one with reflux? Is it a role of already present dysplasia? Is it the timing of treatment of the pyelonephritis? Is it the biology of the bacteria? The patient's immunology? The answer most likely is "yes" to all. I believe we need to worry about all patients with pyelonephritis and until we have a radiologic study that can clearly delineate between scar and dysplasia without having a baseline, it is all a guessing game.

Pediatric Nephrology, 21(4): 521 - 526, April 2006

Written by Pasquale Casale, MD - UroToday

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