Renal Scarring Following Reflux and Nonreflux Pyelonephritis in Children: Evaluation with ^99m Technetium-Dimercaptosuccinic Acid Scintigraphy

Abstract

99mTechnetium dimercaptosuccinic acid (DMSA) scintigraphy is the imaging modality of choice for the detection of acute pyelonephritis and chronic renal scarring in children. Using the DMSA scan we prospectively evaluated renal scarring after reflux and nonreflux pyelonephritis in children. The study population consisted of 33 patients with acute pyelonephritis documented by a DMSA renal scan at infection. The children were evaluated for renal scarring with a followup DMSA scan 4 to 42 months (mean 10.7 months) after the acute infection. All new scarring on followup DMSA scans occurred at sites corresponding exactly to areas of acute inflammation on the initial DMSA scan. Therefore, only those kidneys with acute changes on the initial scan were subsequently analyzed. Of 38 kidneys new or progressive scarring developed in 16 (42%), including 6 of 15 (40%) with associated vesicoureteral reflux and 10 of 23 (43%) without demonstrable reflux. New renal scarring developed in 6 of the 7 kidneys (86%) associated with a neuropathic bladder or posterior urethral valves. In contrast, new scarring developed in only 10 of 31 kidneys (32%) associated with a normal bladder (p = 0.028). Excluding the kidneys associated with a neuropathic bladder or posterior urethral valves, new renal scarring developed in 3 of 12 (25%) with primary reflux, compared with 7 of 19 (37%) without vesicoureteral reflux. Except for the white blood count and the species of infecting bacteria, no other statistically significant differences could be found between those cases in which scars did or did not develop. We conclude that acquired renal scarring only occurs at sites corresponding to previous areas of acute pyelonephritis, the acute parenchymal inflammatory changes of acute pyelonephritis are reversible and do not lead to new renal scarring in the majority of cases, and once acute pyelonephritis has occurred ultimate renal scarring is independent of the presence or absence of vesicoureteral reflux.

Febrile Urinary Tract Infection in Children: Role of 99mTc-Dimercaptosuccinic Acid (Dmsa) Scan and Other Imaging Techniques

“…Recent reports have challenged the assumption that APN in children is usually associated with VUR. 4,11,12 Our study has supported this view; 55% of children with DMSA-documented changes of APN had no VUR. APN in the absence of VUR has been attributed to bacterial virulence, e.g., the presence of P. fimbriae in certain strains of Escherichia coli allowing ascending infection, 4 or due to hematological spread.…”

“…7 Both US and IVU underestimate the degree of renal parenchymal involvement, with a high rate of false-negative results. [5][6][7][8]11 Fifty-eight of our children studied with DMSA scans showed evidence of APN. This is comparable to 66% reported by others.…”

“…This is comparable to the 58% reported in a similar work. 11 However, other factors in the host defense or the virulence of the infecting agent may also affect the outcome of the inflammatory reaction in children with APN. Recent reports have challenged the assumption that APN in children is usually associated with VUR.…”

Renal scars in children with primary vesicoureteral reflux

“…Em crianças com pielonefrite, observou-se semelhante proporção da presença de E. coli entre as que desenvolveram e as que não desenvolveram cicatrizes renais 30 , semelhante ao que ocorreu neste trabalho. Tem-se questionado o risco da maior formação de cicatrizes em pacientes com infecção pela E. coli P fimbriada 7,25,30 .…”

Post-Inflammatory Nephropathy

“…The majority of studies demonstrated that the risk of renal scarring decreases with age and is highest in children in the first year of life (Hansson et al, 1999;Vernon et al, 1997;Arant, 1991;Benador et al, 1997;Smellie et al,1998;Sheu et al, 2009). This may be related to the correction of anatomical and/or functional urinary system abnormalities and the decrease in susceptibility of renal parenchyma to infection due to defense mechanisms maturation (Benador et al, 1997;Rushton et al,1992). Dissimilar results were obtained by Pecile et al (2009).…”