Imaging strategies for vesicoureteral reflux diagnosis

The prevalence of vesicoureteral reflux (VUR), although reported to be low in the general population, is high in children with urinary tract infection (UTI), first degree relatives of patients with known VUR and children with antenatal hydronephrosis. In addition, it has been shown that VUR and UTIs are associated with renal scarring, predisposing to serious long-term complications, i.e., hypertension, chronic renal insufficiency and complications of pregnancy. Therefore, diagnostic imaging for the detection of VUR in the high-risk groups of children has been a standard practice. However, none of these associations has been validated with controlled studies, and recently the value of identifying VUR after a symptomatic UTI has been questioned. In addition, several studies have shown that renal damage may occur in the absence of VUR. On the other hand, some patients, mainly males, may have primary renal damage, associated with high-grade VUR, without UTI. Recently, increasing skepticism has been noted concerning how and for whom it is important to investigate for VUR. It has been suggested that the absence of renal lesions after the first UTI in children may rule out VUR of clinical significance and reinforces the redundancy of invasive diagnostic techniques. Therefore, the priority of imaging strategies should focus on early identification of renal lesions to prevent further deterioration.     

May we go on with antibacterial prophylaxis for urinary tract infections?

Recurrent urinary tract infections (UTIs), with or without vesicoureteric reflux (VUR), are by far the most frequent reason for long-term antibacterial prophylaxis in infants and children today. However, the strategies of antibacterial prophylaxis for the prevention of recurrent urinary tract infection are no longer universally accepted. In infants and children at risk, the benefits of antibacterial prophylaxis definitively are not yet proven by evident data. To put antibacterial prophylaxis in its place, risk groups for recurrent symptomatic infections, ascending UTI and permanent renal damage have to be defined and the efficacy of prophylaxis in these groups has to be proved by prospective randomised studies. Nevertheless, until the results of these studies are available, antibacterial prophylaxis will remain one of the most frequently practised methods to protect risk patients from pyelonephritic damage and UTI recurrences.     

Urinary incontinence in children with primary vesicoureteral reflux--urinary incontinence and function of refluxing kidney

The interrelation among urinary incontinence (nocturnal enuresis, urge incontinence), history of urinary tract infection and renal function was investigated in 153 children with primary vesicoureteral reflux who were more than three years old. Of them, 98 children (64%) had the chief complaint of urinary tract infection (UTI) and 43 children (28%), urinary incontinence. Of the children whose chief complaint was UTI, 44 (45%) had incontinence. Thus, 87 children (57%) with VUR had urinary incontinence. Almost all the children who had urinary incontinence and no previous UTI had good renal function. Renal dysfunction was found in children with previous UTI history. These studies on children with primary VUR more than three years old indicate that, although urinary incontinence could be a factor for recurrence of UTI and a probable cause of worsening of renal function, there is no direct correlation between urinary incontinence and renal dysfunction accompanied by VUR.     

EAU Guidelines on vesicoureteral reflux in children

Context

Primary vesicoureteral reflux (VUR) is a common congenital urinary tract abnormality in children. There is considerable controversy regarding its management. Preservation of kidney function is the main goal of treatment, which necessitates identification of patients requiring early intervention.

Objective

To present a management approach for VUR based on early risk assessment.

Evidence acquisition

A literature search was performed and the data reviewed. From selected papers, data were extracted and analyzed with a focus on risk stratification. The authors recognize that there are limited high-level data on which to base unequivocal recommendations, necessitating a revisiting of this topic in the years to come.

Evidence synthesis

There is no consensus on the optimal management of VUR or on its diagnostic procedures, treatment options, or most effective timing of treatment. By defining risk factors (family history, gender, laterality, age at presentation, presenting symptoms, VUR grade, duplication, and other voiding dysfunctions), early stratification should allow identification of patients at high potential risk of renal scarring and urinary tract infections (UTIs). Imaging is the basis for diagnosis and further management. Standard imaging tests comprise renal and bladder ultrasonography, voiding cystourethrography, and nuclear renal scanning. There is a well-documented link with lower urinary tract dysfunction (LUTD); patients with LUTD and febrile UTI are likely to present with VUR. Diagnosis can be confirmed through a video urodynamic study combined with a urodynamic investigation. Early screening of the siblings and offspring of reflux patients seems indicated.Conservative therapy includes watchful waiting, intermittent or continuous antibiotic prophylaxis, and bladder rehabilitation in patients with LUTD. The goal of the conservative approach is prevention of febrile UTI, since VUR will not damage the kidney when it is free of infection. Interventional therapies include injection of bulking agents and ureteral reimplantation. Reimplantation can be performed using a number of different surgical approaches, with a recent focus on minimally invasive techniques.

Conclusions

While it is important to avoid overtreatment, finding a balance between cases with clinically insignificant VUR and cases that require immediate intervention should be the guiding principle in the management of children presenting with VUR.     

Relationship between acute pyelonephritis, renal scarring, and vesicoureteral reflux

Acute pyelonephritis (APN) may produce permanent renal damage (PRD), which can subsequently lead to diverse complications. We prospectively evaluated 147 females and 122 males (mean age 3.5 years) with APN in order to analyze the relationship between the presence of PRD, at the time of cortical renal scintigraphy, and age, gender, episodes of urinary tract infection (UTI), and presence of vesicoureteral reflux (VUR). There were 152 children studied after the first proven UTI. VUR was present in 150 children. PRD was observed in 170 children. There were no significant differences between boys and girls. PRD was found in 36.4% of children younger than 1 year and in 70.1% of those older than 1 year (P<0.0001). Of children with VUR, 72% had PRD compared with 52% of children without VUR (P<0.0001). Of children with a first episode of UTI, 55.9% developed PRD as did 72.6% of those with recurrent UTI (P=0.004). Our results showed that PRD in children with APN is important, especially in the presence of VUR, recurrent UTI, and older age.     

Vesicoureteral reflux and reflux nephropathy

Primary vesicoureteral reflux (VUR) is the commonest congenital urological abnormality in children, which has been associated with an increased risk of urinary tract infection (UTI) and renal scarring, also called reflux nephropathy (RN). In children, RN is diagnosed mostly after UTI (acquired RN) or during follow-up for antenatally diagnosed hydronephrosis with no prior UTI (congenital RN). The acquired RN is more common in female children, whereas the congenital RN is more common in male children. This observation in children might help explain the differences in the clinical presentation of RN in adults, with males presenting mostly with hypertension, proteinuria, and progressive renal failure as compared with females who present mostly with recurrent UTI and have a better outcome. Known risk factors for RN include the severity of VUR, recurrent UTI, and bladder-bowel dysfunction; younger age and delay in treatment of UTI are believed to be other risk factors. Management of VUR is controversial and includes antimicrobial prophylaxis, surgical intervention, or surveillance only. No evidence-based guidelines exist for appropriate follow-up of patients with RN.     

Vesicoureteral reflux, a benign condition

The combination of urinary tract infection (UTI) and vesicoureteral reflux (VUR) is commonly thought to predispose the child to pyelonephritis, renal scarring and, later in life, to hypertension or end-stage renal disease (ESRD). This paradigm has led to the active search, follow-up and treatment of VUR, and also prevention of recurrent UTI in children. The causality of VUR and ESRD is controversial, however. According to recent meta-analyses it is uncertain whether we can prevent renal scarring or ESRD by treating VUR. Studies on VUR are abundant, but the findings and conclusions are confounding. Because of the lack of evidence of the role of VUR, reasonable doubt has recently been presented on the rationale of imaging all children with UTI and treating the children with VUR. The overall importance of VUR is confounded because of the natural tendency of VUR to resolve spontaneously, its dynamic nature, and its different grades in children. The historical studies showing that VUR is much more common, even among healthy children, than usually claimed, have been forgotten. Since it seems that we are referring too many healthy children to unpleasant and possibly unnecessary imaging tests for VUR, we are uncertain when and what kind of VUR—if any—we should treat, and whether our present rationale of addressing VUR truly makes any difference to renal scarring or ESRD in children, we should critically revisit the subject of VUR.     

Split renal function does not change after successful treatment in children with primary vesico-ureteric reflux

OBJECTIVE: To evaluate the renal growth pattern in patients with primary vesico-ureteric reflux (VUR) using long-term measurements of split renal function with 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. PATIENTS AND METHODS: In all, 712 children aged < 16 years (466 boys and 246 girls) with primary VUR were referred to our hospital from July 1991 to December 2000. VUR was diagnosed by voiding cysto-urethrography. The patients were treated either surgically (group 1) or conservatively (group 2) and followed with serial 99mTc-DMSA scintigraphy for up to 10 years. There were 942 examinations in 367 of 712 patients who had repeat scintigraphy. Patients with secondary VUR, VUR to a solitary or fused kidney, or upper urinary tract obstruction, were excluded. Five of 298 patients (1.7%) who had ureteric reimplantation had a febrile urinary tract infection (UTI) soon after surgery but none recurred (recurrence is an indication for surgery in children with VUR); there was no febrile UTI in the 69 patients in group 2. Planar scintigraphy with 99mTc-DMSA was used to assess the absolute uptake (AU) of each kidney, measured as a percentage of the injected dose, and the relative uptake (RU = AU of each kidney/AU of both kidneys) calculated. The initial examination was at least 4 weeks after any febrile UTI in most patients. Serial studies were conducted 1 year after surgery and then biannually in group 1. In group 2 the DMSA scan was repeated every 2-3 years. The change in split renal function was compared with the RU of the right kidney. RESULTS: The RU of the right kidney at the initial scan correlated closely with those on repeated scans in both groups. The correlation coefficients were 0.99 in group 1 and 0.94-0.97 in group 2 at every study. The change of RU remained within 0.05 in all patients after treatment. CONCLUSIONS: Under strict control of UTI, split renal function in children with primary VUR does not change. There may be no possibility of accelerated or compensatory growth of the kidney with reflux nephropathy, but no concern about deterioration and atrophy either.     

Dimercapto-succinic acid scintigraphy instead of voiding cystourethrography for infants with urinary tract infection

PURPOSE: We study the ability of dimercapto-succinic acid (DMSA) scintigraphy to predict the presence of dilating vesicoureteral reflux (VUR) in infants with urinary tract infection (UTI) to simplify the evaluation protocol. MATERIALS AND METHODS: A retrospective analysis of the records of 303 children younger than 2 years with initial UTI investigated with DMSA scintigraphy and voiding cystourethrography (VCU) within 3 months after UTI was performed. RESULTS: In 156 of the 303 children (51%) DMSA scintigraphy showed renal lesions. VUR was found in 80 patients (26%) and VUR grade significantly correlated with the presence of renal lesions. A normal DMSA scintigraphy and dilating VUR (grade III) occurred in 7 infants. At followup after 1 to 2 years, 6 of these 7 patients had normal DMSA scans and 1 had a scarred duplex kidney. VUR resolved spontaneously in 5 and improved spontaneously to grade 1 in 2 patients. None of the 7 children had recurrent UTI. CONCLUSIONS: DMSA scintigraphy in infants with UTI may replace VCU as a first line investigation. A strategy to perform VCU in only patients with renal lesions is proposed. In this study 147 of 303 VCUs would have been unnecessary as only 1 child with a damaged kidney was missed.     

Medical management of vesicoureteral reflux

Vesicoureteral reflux (VUR) in children is associated with increased risk of urinary tract infection (UTI). Recurrent UTI in the presence of the VUR is believed to cause renal scarring, which carries a risk of subsequent hypertension, toxemia of pregnancy, and significant renal damage, including end-stage renal disease. The natural history of VUR is to improve or resolve completely with time in most of the patients. The traditional management consists of prompt treatment of UTI, long-term anti-microbial prophylaxis until the VUR resolves, or surgical intervention in those with persistent high grade VUR, recurrent UTI in spite of prophylaxis with anti-microbial agent, allergy to anti-microbial agents, and patient/parent non-compliance with the medical management. Voiding dysfunction and constipation play an important role, and their diagnosis and appropriate management helps reduce the frequency of UTI and promote the resolution of the VUR. Patients with renal scarring need to be monitored for potential complications such as hypertension, proteinuria, and progression of the renal damage. In patients with hypertension and/or proteinuria, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) are the drugs of choice, because of their reno-protective properties. Recent studies have revealed that there is no convincing evidence that UTI in the presence of VUR predicts renal injury or that the use of long-term anti-microbial prophylaxis or surgical intervention prevents renal scarring or its progression. However, until proven otherwise by a prospective, placebo-controlled, randomized study, it is advisable to err on the side of caution and consider VUR and UTI risk factors for renal scarring and treat each patient on individual basis.     

Recurrence and follow-up after urinary tract infection under the age of 1 year

In order to analyze the risk factors for recurrence and the value of routine follow-up by monthly urine cultures in a group of children who had their first episode of urinary tract infection (UTI) under 1 year of age, we performed a retrospective survey of 262 children (134 girls, 128 boys) who were treated for their first UTI while aged under 1 year in the Department of Pediatrics, University of Oulu, during the years 1978–1984. Detailed data on these children concerning their first and recurrent UTIs were collected from hospital records using a formulated data sheet. Causative bacteria and vesicoureteral reflux (VUR) were analyzed as possible risk factors for recurrent UTI. The time of recurrence and the possible symptoms during the recurrent UTI were also investigated. The follow-up period after the first UTI was 3 years; 35% of the boys and 32% of the girls contracted a recurrent UTI during the 3-year follow-up. In 86% of cases, the first UTI recurrence occurred within 6 months of the primary UTI. Recurrent UTIs were detected significantly earlier with routine monthly follow-up compared with those seeking treatment because of symptoms (log rank test P<0.01). There was a significant difference in the number of recurrences of UTI according to the grade of VUR (P=0.006). Recurrence-free survival was shorter and recurrent UTIs occurred more often in the children with grade 3–5 VUR than in those with grade 0–2 VUR (log rank test P=0.0005). Children without VUR and children with grade 1–2 VUR did not differ in the recurrence rate, and thus grade 1–2 VUR did not increase the risk for recurrent UTI. Monthly routine urine cultures are efficient in detecting recurrent UTI infections in children. Since grade 3–5 VUR is a risk factor both for increased recurrence rate of UTI and for possible subsequent renal damage, these children should be followed with monthly urine cultures for UTI recurrences if not on preventive medication. Since the vast majority of UTI recurrences occur within 6 months of the first UTI, routine follow-up for 6 months seems to be sufficient after symptomatic UTI in children with grade 3–5 VUR. Received: 10 January 2000 / Revised: 21 August 2000 / Accepted: 21 August 2000     

Paediatric urinary tract infection and the necessity of complete urological imaging

OBJECTIVE: To evaluate voiding cysto-urethrography (VCUG) in assessing children with urinary tract infection (UTI) when renal/bladder ultrasonography and renal scintigraphy show no abnormality. PATIENTS AND METHODS: A total of 468 renal scintigrams taken in children for an indication of UTI between January 1996 and December 1998 were reviewed. The renal and bladder ultrasonograms of those children with a normal renal scan were then reviewed. Children with both normal renal scans and normal ultrasonography were then evaluated for the frequency and grade of vesico-ureteric reflux (VUR) on VCUG. RESULTS: Of the 468 patients, 453 (97%) had complete imaging studies; 152 of the children evaluated had normal renal scans, of whom 101 had a normal renal ultrasonogram. Twenty-three (23%) children with both a normal renal scan and renal/bladder ultrasonogram showed VUR on VCUG, of whom 14 had bilateral VUR and 13 grade III or higher VUR. CONCLUSION: This study indicates that about 23% of patients may have significant VUR despite both a normal renal scan and ultrasonogram. Therefore, VCUG remains important in evaluating and managing children with UTI.     

Prevalence of hydronephrosis and vesicoureteral reflux in pediatric urinary tract infection

We studied 108 children diagnosed with urinary tract infection (UTI) to determine the frequency of hydronephrosis and vesicoureteral reflux (VUR). Fifty-two children (48.1%) had hydronephrosis (pyeloureteral junction obstruction: 27.8%) and 43 children (39.8%) had VUR (primary VUR: 36.1%). A renal scar was seen in 25.8% of the VUR cases. We recognized again that children with a history of UTI need to be examined promptly and thoroughly.     

Urinary tract infection: one lingering effect of childhood kidney diseases--review of the literature

Urinary tract infection (UTI) is a possible warning sign of the presence of anomalies of the urinary tract. Following a UTI there is concern with recurrences which can contribute to scarring which may lead to hypertension, pregnancy-induced hypertension and even renal failure in later years. Prospective studies using 99mTc-labeled dimercaptosuccinic acid (DMSA) have shown that 30%-40% of children will have renal scarring after febrile UTI, regardless of the presence or absence of vesicoureteral reflux (VUR). Many studies have demonstrated that VUR is an important risk factor for renal scarring after UTI. Hypertension affects at least 10% of children with renal scarring, and in adults with reflux nephropathy (RN), the prevalence of hypertension is also much higher (38%-50%). UTI, pregnancy-induced hypertension (PIH) or renal function deterioration alone or in some combination has been reported to be as high as 39% in women with renal scarring. RN is one of the important causes of end-stage renal disease (ESRD) worldwide. Prevention of renal scar development should reduce the incidence of hypertension in patients as they age. The appropriate management of childhood UTI includes education of parents, patients and general physicians to be sure that everyone is aware of not only the current condition, but also the possibility of future UTI-related situations. In conclusion: UTI itself is a warning sign of possible anomalies of the urinary tract, renal problems and/or chronic renal complications. Although VUR is primarily a disease of childhood, scarring from the disease can cause problems in later years, with the complicating factor that because only the renal scar remains, the VUR may be forgotten and not considered when diagnosing the current problem.     

Imaging in childhood urinary tract infections: time to reduce investigations

The correct protocol for investigating urinary tract infections (UTI) is unknown but remains a hotly debated topic. The main objective in investigating children with UTI is to prevent the long-term complications of developing hypertension, chronic kidney disease (CKD) and/or pregnancy complications. However, the prognosis for childhood UTI remains good, with low long-term risks, from epidemiological studies, of developing these sequelae. Although childhood UTI is common, the occurrence of CKD and the likelihood that acute pyelonephritis will cause renal damage progressing to CKD are rare. We studied the current literature on investigations of childhood UTI and propose a protocol for carrying out selected investigations in high-risk children. By identifying this group of children with increased risk of having an abnormal urinary tract that warrant investigation, we recommend that targeting investigations to specific children (as opposed to protocol-based investigations of all children with UTI), will be clinically safe and effective and will avoid the unnecessary distress and cost of invasive investigations.     

Primärer vesikoureteraler Reflux

The never ending discussion about the diagnostics and treatment of vesicoureteral reflux (VUR) now includes arguments for diagnostic nihilism as well as invasive diagnostics and therapy, which is reminiscent of the debate on prostate cancer in adulthood. The common goal of all currently competing diagnostic strategies and approaches is the prevention of renal scars by the most effective and least burdensome approach. There is a difference between acquired pyelonephritic scars with VUR (acquired reflux nephropathy) and congenital reflux nephropathy (primary dysplasia) which cannot be influenced by any therapy. The VUR can be verified by conventional radiological voiding cystourethrography (VCUG), by urosonography, radionuclide cystography or even by magnetic resonance imaging (MRI). The guidelines of the European Association of Urology/European Society for Paediatric Urology (EAU/ESPU) recommend radiological screening for VUR after the first febrile urinary tract infection. Significant risk factors in patients with VUR are recurrent urinary tract infections (UTI) and parenchymal scarring and the patients should undergo patient and risk-adapted therapy. Infants with dilating reflux have a higher risk of renal scarring than those without dilatation of the renal pelvis. Bladder dysfunction or dysfunctional elimination syndrome represents a well-known but previously neglected risk factor in combination with VUR and should be treated prior to any surgical intervention as far as is possible. Certainly not every patient with VUR needs therapy. The current treatment strategies take into account age and gender, the presence of dysplastic or pyelonephritic renal scars, the clinical symptoms, bladder dysfunction and frequency and severity of recurrent UTI as criteria for the therapy decision. The use of an antibacterial prophylaxis as well as the duration is controversially discussed. Endoscopic therapy can be a good alternative to antibacterial prophylaxis or a surveillance strategy in patients with low grade VUR. In patients with dilating VUR and given indications for surgery, endoscopic treatment can be offered. However, parents should be completely informed about the significantly lower success rate of endoscopic therapy compared to open surgical procedures. The open surgical techniques guarantee the highest success rates and should be used in patients with a dilating VUR and high risk of renal damage.     

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

The finding of scintigraphic renal defects in children with febrile urinary tract infection (UTI) even in the absence of vesicoureteric reflux (VUR) has led to the conclusion that VUR is a weak predictor of renal defects in these patients. We used isotopic cystography (IC) for diagnosis of VUR in children with febrile UTI. Dimercaptosuccinic acid renal scintigraphy was performed 6 months after cure of the last UTI. Renal defects were defined by the finding 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 subjects 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). Permanent renal defects in children with febrile UTI are closely associated with VUR. 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.     

Vesicoureteric reflux in Kuwaiti children with first febrile urinary tract infection

The prevalence of vesicoureteric reflux (VUR) in children with urinary tract infection (UTI) varies among different racial groups. The purpose of this study was to determine the frequency of VUR and associated renal changes in a group of Arab Kuwaiti children with their first documented febrile UTI and to compare our findings with those reported from other racial groups. One hundred and seventy-four children (38 males and 136 females) fulfilled the study criteria and were divided into three age groups (<1 year, 1–5 years, and >5 years). Patients in each group had both micturating cystourethrography (MCUG) and 99m-Tc-dimercaptosuccinic acid (DMSA) renal scan after diagnosis. VUR was detected in 39 children (22%). Two-thirds of cases had mild reflux (grade I and II). Females (n=32) had more reflux than males (n=7) (24% vs. 18%). Sixty-three patients (36%) had abnormal (DMSA) renal scans (acute pyelonephritis [AP] or renal scars). Of these, 79% were children below 5 years. Abnormal DMSA scans were found in 4 of 38 males (11%) versus 59 of 136 females (43%). Abnormal scans in children with VUR were seen in 1 of 7 males (14%) versus 19 of 32 females (59%). In total, the combination of abnormal scan with VUR occurred in 1 of 38 males (3%) and in 19 of 136 females (14%), whereas abnormal scan without demonstrable VUR was seen in 3 of 38 males (8%) versus 40 of 136 females (29%). Our data showed that the frequency of VUR in Arab Kuwaiti children with febrile UTI is midway between Caucasian and other racial groups. In this study, males had a lower-risk profile than females, the latter having a higher rate of reflux as well as a higher rate of abnormal DMSA scans, irrespective of demonstrable VUR.     

Renal pelvic wall thickening in childhood urinary tract infections--evidence of acute pyelitis or vesicoureteral reflux?

OBJECTIVE: The aim of this study was to determine whether renal pelvic wall thickening in active childhood urinary tract infections (UTIs), as demonstrated using ultrasound, is caused by acute pyelitis or by vesicoureteral reflux (VUR)-related chronic changes. MATERIAL AND METHODS: A total of 41 children with at least unilateral renal pelvic wall thickening as demonstrated using ultrasound during the acute stage of UTI, and confirmed using voiding cystourethrography (VCUG), were analyzed. All cases underwent ultrasound studies at 6 months follow-up. RESULTS: Using ultrasound, 50 halves of the pelvis showed renal pelvic wall thickening. In 27 (54%), ipsilateral VUR could be demonstrated using VCUG. The sensitivity, specificity and positive predictive value of renal pelvic wall thickening for predicting ipsilateral VUR were 79.4%, 52.1% and 54%, respectively. Only 2 (7%) cases presented with wall thickening at 6 months follow-up. Most of the thickening recovered after clinical improvement, although VUR became persistent in half the cases. CONCLUSIONS: Renal pelvic wall thickening is an abnormal finding in the acute stage of childhood UTI and predominantly indicates acute pyelitis rather than VUR-related chronic changes. Renal pelvic wall thickening is not sufficiently predictive of VUR in acute UTI, although it does provide evidence of upper UTI.     

Post-pyelonephritic renal scars are not associated with vesicoureteral reflux in children

PURPOSE: Children with pyelonephritis are at risk for renal damage. We assess the value of clinical signs and urological abnormalities in predicting renal scars in children following pyelonephritis. MATERIALS AND METHODS: A total of 64 hospitalized children (29 females and 35 males, median age 2.9 years) underwent ultrasonography and technetium labeled dimercapto-succinic acid (DMSA) scintigraphy imaging within 1 week following the diagnosis of the first pyelonephritis. Voiding cystourethrography was performed 8 weeks after the diagnosis. Followup DMSA scintigraphy was performed in 58 patients after 2 years of followup. RESULTS: Urological abnormalities observed were vesicoureteral reflux (VUR, grade 2 or higher) in 11 patients (19%), nonrefluxing and nonobstructed megaureter in 2 (4%) and pyeloureteral obstruction in 1 (2%). The first DMSA scintigraphy showed parenchymal defects in 48% of patients. VUR did not increase the risk of renal defects. At 2 years after the infection 12 of the 58 patients (21%) had renal scars. Nine of these patients did not have VUR. However, 2 patients with high grade VUR and repeat infections demonstrated deterioration of kidney function during followup. The patients with renal scars were older than those without scars (3.1 vs 0.8 years, p = 0.0291) at the time of infection. CONCLUSIONS: Renal scars after first pyelonephritis are in most cases not associated with abnormalities of the urinary tract, but are caused by the infection itself. However, structural abnormalities may predispose to recurrent infections. Following pyelonephritis new renal scars may develop in all age groups in both sexes.