Development of new renal scars: a collaborative study

99mtechnetium-dimercapto-succinic acid renal scanning and excretory urography in diagnosis of renal scars in children

We compared the ability of excretory urography (without tomography) and 99mtechnetium-dimercapto-succinic acid renal scanning to detect renal scars in 32 children with primary vesicoureteral reflux. These children did not have hydronephrosis, renal failure or urinary tract obstruction. In all cases both studies were conducted within a 10-month period. The findings from both modalities were in agreement for 51 of the 64 renal units evaluated (80 per cent). Evaluation of the excretory urogram indicated 6 cases of diffuse and 2 of focal scarring that were not detected by evaluation of the renal scan. The sensitivity of excretory urography to detect renal scars was 84 per cent and the specificity was 83 per cent. The 99mtechnetium-dimercapto-succinic acid renal scan showed 5 cases of focal renal scarring not detected by excretory urography. The sensitivity of the renal scan to detect renal scars was 77 per cent and the specificity was 75 per cent. We conclude that neither study alone could effectively replace the other for the detection of renal scars, and recommend that both be included in the initial evaluation and followup of patients with renal scars.

Physical growth velocity during conservative treatment and following subsequent surgical treatment for primary vesicoureteric reflux

Physical growth was studied in 6 males and 16 females during 1 year of antimicrobial prophylaxis and during the 2 years following subsequent surgical treatment for severe primary vesicoureteric reflux. Surgery was performed between the ages of 2 and 8 because of either repeated breakthrough infection or persistence of grade III or IV reflux. Height and weight velocities were calculated as yearly rates and then converted into interquartile ratios (IQRs). Neither the mean centile height nor weight attained varied significantly between that at entry, after 1 year of medical treatment and at 2 years after surgery. However, the mean IQR for height velocity (+/- sem) rose significantly from -0.61 (+/- 0.45) during antimicrobial prophylaxis to 0.54 (+/- 0.25) following surgery. Similarly, the mean IQR for weight velocity rose significantly from -0.63 (+/- 0.50) during medical treatment to 0.47 (+/- 0.24) following surgery. These results suggest that surgical treatment is preferable to continued medical treatment in patients with severe primary vesicoureteric reflux who fail to respond to a trial of antimicrobial prophylaxis.

New development and progression of renal scarring in children with primary VUR

To study the development of new scars and progression of previous scarring, we analysed 711 children with primary VUR. New scar or progression of previous scarring was observed in 7.3% of the kidneys with reflux. Factors which promote the formation of new scars are high-grade VUR, recurrent UTIs and high-pressure bladder which results in high-pressure reflux. The average age of new scarring was from 7 to 9 years. We emphasize the importance of the follow-up study until the age of 15 years, even after reflux has stopped following surgery.

Bacterial and host determinants of renal scarring

This review summarizes recent work examining the interaction between host and parasite in recurrent urinary tract infection (UTI) and renal scarring. Virulence in uropathogenic E. coli has been defined by the severity of acute disease. Isolates from patients with acute pyelonephritic strains differ from those causing asymptomatic bacteriuria by multiple traits which contribute to virulence, and which are coexpressed in a non-random manner. The single marker most characteristic for the pyelonephritogenic clones is bacterial adherence to uroepithelial cells binding specifically to the disaccaride Gal alpha 1-4 Gal beta within the globoseries of glycolipids. The notion that the most severe consequence of acute pyelonephritis, i.e. renal scarring, was caused by the most virulent clones, was contradicted by comparison of pyelonephritic strains isolated from children with and without scarring. The virulent clones were significantly less frequent in patients with renal scarring (22%) than in patients with recurrent pyelonephritis not developing renal scars (62%). In view of the unexpected inverse association of bacterial virulence with renal scarring lack of Gal alpha 1-4 Gal beta binding capacity of E. coli strains was found to predict the risk for renal scarring among boys with first-time acute pyelonephritis. Vesicoureteric reflux (VUR) is widely accepted as a host determinant of susceptibility to pyelonephritis and renal scarring. In our study the frequency of renal scarring was 57% among girls with VUR as compared to 8% of those without. The reflux alone did however, not explain the selection of bacteria of low virulence. Individuals prone to UTI and renal scarring were found to be a genetically selected subgroup of the general population. A correlation between P1 blood group phenotype and susceptibility to UTI and between blood group non-secretor state and renal scarring was found. The mechanisms behind these relationships need to be defined. The bacterial and host parameters combined indicate that host parameters are essential for the tendency to develop renal scarring after acute pyelonephritis.

Renal growth and progression of reflux nephropathy in children with vesicoureteral reflux

We analyzed renal growth and development of renal scars in 754 children with primary and 169 with secondary vesicoureteral reflux. The incidence of a small kidney was 15.5 per cent in the primary and 24.1 per cent in the secondary groups. About three-fourths of the small kidneys remained small from the first examination through followup. Catch-up renal growth was only exceptional. New scars or progression of previous scarring was observed in 7.4 and 30 per cent of the primary and secondary groups, respectively. Factors that promote formation of new scars are high grade vesicoureteral reflux, recurrent urinary tract infections and abnormal bladder function that results in high pressure reflux. We emphasized the importance of precise examination of the lower urinary tract. An early antireflux operation should be performed on children with severe reflux or recurrent urinary tract infections.

Is ultrasound screening for urinary tract infection "cost effective"?

We prospectively followed 110 patients for 1 year who underwent initial imaging evaluation of the upper urinary tract for infection, monitoring both clinical efficacy and cost. Eighty-seven of the patients had ultrasound studies and 23 had excretory urograms. In our experience, ultrasound screening did not increase the utilization of other upper urinary tract imaging procedures although patient costs were increased solely because of the greater charge for ultrasound relative to excretory urography at our institution.

The small scarred kidney of childhood. A congenital or an acquired lesion?

The vast majority of small segmentally scarred kidneys seen in childhood are now recognised to be associated with vesicoureteric reflux and the term "reflux nephropathy" has been accorded general recognition as a description of this renal lesion. With regard to the pathogenic mechanisms responsible for the scarring process, the possible roles of intrauterine renal maldevelopment, bladder dysfunction, functional urinary obstruction and infection in relation to vesicoureteric reflux and the associated phenomenon of intrarenal reflux must all be considered. It is probable that in different clinical circumstances all of these factors may be important to varying degrees and discussion of their contributions to the spectrum of reflex nephropathy is the basis of this communication.

Pediatric urinary tract infection. Diagnosis, classification, and significance

The initial task is to establish the diagnosis of a urinary tract infection. The clinical setting, method of specimen collection, bacterial colony count, and species are all important considerations. Next, the infection is classified as complicated or uncomplicated. Complicated infections require hospitalization and parenteral antibiotic therapy. Appropriate imaging studies are imperative to determine whether urologic intervention is necessary. All children with well-documented urinary tract infections deserve diagnostic evaluation, regardless of sex or presence of systemic symptoms.

Vesico-uretero-renal reflux and the kidney

The most frequent complications of non-obstructive vesico-uretero-renal reflux (VUR) are segmental renal scars. These scars are confined to segments with intrarenal reflux which are, in addition, exposed to bacterial infection. Primarily, only gaping collecting duct orifices, confined to compound papillae and mainly situated at the kidney poles, allow intrarenal reflux. Scar contraction and obstruction seem to be able to transform closed collecting duct orifices into gaping ones, thereby enlarging the parenchymal area prone to intrarenal reflux and to renal scarring. Contrary to earlier reports, a recent survey has documented that new scars in children develop with significant frequency beyond 5 years of age. There is a greater tendency for scarring to develop with more severe VUR, but new renal scars can develop with all grades of VUR. Early and adequate antibiotic treatment decreases the extent of scarring. The results of experimental studies in which renal scarring developed in piglets with bladder decompensation resulting from intravesical obstruction but without bacterial infection may be relevant to the few children with proximal urethral valves and hypertonic neurogenic bladders but not to the large number with non-neurogenic detrusor instability or detrusor sphincter dyssynergia. Prospective studies have not shown different recurrence rates of urinary tract infections in medically managed compared with surgically managed children. The frequency of acute pyelonephritic attacks decreased significantly after operation.

Management of children with unobstructed urinary tract infection

There are two major considerations when taking care of children with urinary tract infection (UTI): firstly to prevent renal damage and secondly to relieve symptoms. A distinction should always be made between these two aims, since they often concern separate populations that may need different treatment and follow-up strategies. Acute pyelonephritis is a common disorder of infancy and early childhood which is easily overlooked. In all infants and children in whom the cause of fever is not apparent and in all those failing to thrive, urine should be examined by dip slide culture and by an estimation of leucocyte content. With adequate care the immediate and long-term prognosis of acute pyelonephritis is excellent. Thus prevention of kidney damage is mainly a matter of putting existing knowledge into practice. Uncomplicated recurrent lower UTI involves a low risk of renal damage. Short courses of antibiotic treatment easily eradicate most such infections but have no effect on the mechanisms underlying the susceptibility to recurrence. Single-dose therapy should be considered in such instances. Long-term antibiotic prophylaxis is mainly indicated in children with a high risk of renal scarring. Treatment is not recommended for children with asymptomatic bacteriuria.

Prospective trial of operative versus non-operative treatment of severe vesicoureteric reflux in children: five years' observation. Birmingham Reflux Study Group

Children with severe vesicoureteric reflux were allocated randomly to either operative or non-operative treatment and followed up. Altogether 161 children were observed for two years, of whom 104 were followed up for five years. Reflux was abolished in 98% of ureters reimplanted, but more than half of the patients treated non-operatively continued to show severe reflux at five years. Two patients progressed to end stage renal failure, and a further four with extensive bilateral renal scarring became hypertensive. There were no significant differences between treatment groups in the incidence of breakthrough urinary infection, renal excretory function and concentrating ability, renal growth, progression of existing renal scars, or new scar formation. Progressive scarring occurred at all ages but was significantly more common during the first two years' observation. Furthermore, new scars developed exclusively during the first two years' observation, affecting 10 children aged 2-7 at allocation. Neither treatment can claim superiority or fully protect the kidneys from further damage, and efforts must continue to be directed towards identifying those at risk before scarring develops.

Reflux nephropathy

This article reviews current concepts of reflux nephropathy, including the pathophysiology, diagnosis, relationship to infection, role in causing end-stage renal disease, and appropriate treatment and management. The condition is defined from a epidemiologic point of view herein, and attention also is given to possible progressions this condition can take.

Urinary infections in children 1985

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