Vesicoureteric reflux and renal injury

Renal injury associated with the intrarenal reflux (IRR) of urine that is either infected, under high pressure, or both, is a major cause of severe hypertension during childhood and adolescence and of chronic renal insufficiency in patients less than 30 years of age. Many, but not all, adolescent and adult patients with reflux nephropathy (RN) give a history of urinary tract infection (UTI) or unexplained fevers in infancy or early childhood, when the kidney is thought to be at greatest risk of injury. Although vesicoureteric reflux (VUR) is observed more commonly in infants than children with UTI, it is rare in uninfected patients at any age and should never be considered a normal finding during human development. Renal scarring may not be obvious in radiographic or radionuclear studies to medical management alone, no definite benefit of one over the other was observed, regardless of the grade of VUR. Moreover, progressive renal injury in scarred kidneys has been noted even after VUR had been corrected, when infection had been prevented, and while hypertension had been controlled satisfactorily. Focal glomerular sclerosis, a lesion found in patients with proteinuria and RN, has been identified not only in scarred kidneys, but also may be seen in contralateral, unscarred kidneys without VUR, which might suggest a humoral factor or, perhaps, a hyperfiltration phenomenon. RN is one of the most frequent causes of end-stage renal disease (ESRD) in children, adolescents, and young adults, which is potentially preventable. However, prevention will depend on early identification of patients at risk--infants and young children after the first UTI and siblings of patients with VUR--aggressive and effective treatment of UTI, minimizing intravesical pressure, and education of patients, parents, and physicians.     

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.     

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.     

Update on dimercaptosuccinic acid renal scanning in children with urinary tract infection

The dimercaptosuccinic acid (DMSA) renal scan is a method for assessing kidney function. Indications for DMSA scanning in children with urinary tract infection (UTI), as well as timing, have changed. Pitfalls in interpreting DMSA scans include: (1) acute pyelonephritis (APN), (2) tubular dysfunction, (3) hypertension, (4) use of captopril in patients with renovascular hypertension and (5) duplex kidneys. Interpretation of DMSA scans in children with UTI vary according to timing and clinical setting. During the course of a febrile UTI a DMSA scan may reveal a normal kidney, APN or a non-functioning, small and/or ectopic kidney. In the absence of UTI (up to 6 months) in children with vesicoureteric reflux a DMSA scan may indicate a normal kidney, renal scarring (reflux nephropathy), occult duplex kidney and allows the progression of scarring and hypertrophy of normal areas of the kidney to be followed anatomically. The DMSA renal scan in now the most reliable test for the diagnosis of APN. The transient abnormalities due to APN can occur in normal or scarred kidneys. Lesions due to reflux nephropathy (defined as a defect in the renal outline or contraction of the whole kidney) are permanent. Intravenous urography reveals renal abnormalities later than the DMSA scan. If abnormalities are seen on a DMSA scan performed during the course of APN it is impossible to predict the outcome: they can progress to permanent scarring or heal completely. An abnormal DMSA scan during a febrile UTI allows the identification of children at risk of developing renal scars. These children should be carefully investigated, maintained on long-term quimioprophylaxis and followed.     

The small scarred kidney in childhood

Reflux nephropathy is now a generally accepted term to describe small scarred kidneys discovered during childhood; it recognises the close association between this renal lesion and vesicoureteric reflux (VUR). This paper briefly reviews the pathogenic factors involved in reflux nephropathy and suggests that at least two main mechanisms operate: acquired segmental scarring due to intrarenal reflux and congenital maldevelopment (renal dysplasia). The spectrum of renal changes associated with VUR can be usefully divided on this basis and the opportunity to recognise by fetal ultrasound those renal lesions acquired in utero may further enhance our understanding of the congenital maldevelopment group.Presented at the Festschrift for Professor R. H. R. White on March 6, 1992, Birmingham, UK     

The role of imaging in urinary tract infections

The aim of imaging in urinary tract infections (UTI) is to detect conditions that must be corrected to avoid imminent deterioration of kidney function, or to prevent recurrent infections and long-term kidney damage. The most threatening conditions are obstruction of an infected upper tract and abscesses of the genitourinary system. An image-guided percutaneous drainage can be lifesaving. The role of imaging in small children with UTI is controversial in terms of the importance of anatomical and functional disorders in relation to the preventive measures to be taken. In newborns identified with hydronephrosis during pregnancy or by neonatal screening, vesicoureteral reflux (VUR) and renal scarring are congenital and not caused by infection. Most of these patients are males and the VUR is of a higher grade than VUR detected in girls after the first UTI. Imaging in children with UTI should only be ordered after a thorough evaluation of the risk of renal damage and the benefits of preventive measures. In adult females, no imaging is necessary in cystitis, while ultrasonography and plain films are recommended in acute pyelonephritis. Since uncomplicated UTI in men is rare, diagnostic imaging should be started early to rule out complicating factors in the urinary tract. In prostatitis, vesiculitis, epididymitis and orchitis the role of imaging is to rule out abscess formation and testicular malignancies.     

Impressive renal damage after acute pyelonephritis in a child

Urinary tract infection (UTI) is one of the most common bacterial infections in children, and its role in the pathogenesis of scarred kidney is debated. We report on a 7-year-old child who presented with severe UTI. The early (day 4) renal computed tomography (CT) scan showed normal-sized kidneys (110 mm on the left, 105 mm on the right), whereas the control CT scan and dimercaptosuccinic acid (DMSA) scan, performed 1 and 2 months later, respectively, showed a small scarred right kidney (60 mm) with a 12% residual function. An intermittent right vesicoureteral reflux (VUR) was diagnosed by direct isotopic cystography and then treated by Cohen vesicoureteral reimplantation. The patient remained free of infectious recurrence, hypertension, or renal function decrease. This report demonstrates that one episode of acute pyelonephritis can lead to severe renal scarring. Whereas antenatal lesions are thought to have a stronger role in the causal pathway for reflux nephropathy than is UTI in addition to VUR, this observation reminds us that UTI can truly play an important role in damaging kidneys.     

The Efficacy of Tc99m Dimercaptosuccinic Acid (Tc-DMSA) Scintigraphy and Ultrasonography in Detecting Renal Scars in Children with Primary Vesicoureteral Reflux (VUR)

Introduction: Pyelonephritis-induced renal scarring in children is a major predisposing factor for proteinuria, hypertension, and ultimate renal failure. The aim of this study was to investigate and compare the efficacy of Tc99m dimercaptosuccinic acid (Tc-DMSA) renal scintigraphy and renal ultrasonography (USG) in detecting renal scars in children with primary vesicoureteral reflux (VUR). Materials and methods: Tc-DMSA scan and USG studies were done in 62 children who were admitted to our clinic between 1997 and 2003 because of documented urinary tract infection (UTI) and diagnosed with primary VUR. Renal scarring detection rates of Tc-DMSA scan and USG were compared according to reflux grades. Results: In the whole group, renal scars were detected by Tc-DMSA scan and USG in 55% and 38% of refluxing units, respectively. Detection rates of Tc-DMSA and USG according to reflux grades were as follows: 47% and 29 % in low-grade VUR (grades 1 and 2), 46 % and 25% in mid-grade VUR (grade 3), 76% and 65% in high-grade VUR (grades 4 and 5), respectively. Conclusion: USG was found to be an inappropriate study in the detection of renal parenchymal scars, irrespective of the reflux grade. In this study, Tc-DMSA scan detected scars in 35% of kidneys reported to be normal on USG.     

Therapy for vesicoureteral reflux: Antibiotic prophylaxis,urotherapy, open surgery,endoscopic injection,or observation?

Vesicoureteral reflux (VUR) refers to the retrograde flow of urine from the bladder into the ureter and renal pelvis. It generally results from congenital maldevelopment of the ureterovesical junction, although VUR may develop in individuals with abnormally high detrusor pressure. VUR increases a child’s susceptibility to pyelonephritis and renal scarring. Treatment goals include the prevention of pyelonephritis, reflux nephropathy, and other complications of reflux. Treatment alternatives include antibiotic prophylaxis, urotherapy (correction of voiding dysfunction), and surgical correction (open, injection therapy, or laparoscopic). Recent studies have challenged the presumed benefit of prophylaxis in children with VUR, while long-term retrospective studies have documented a high rate of hypertension in adults with reflux nephropathy. In addition, the risk of persistent VUR in adulthood is unresolved. These reports have stimulated a reevaluation of the role of various treatment options in children with VUR.     

Can prompt treatment of childhood UTI prevent kidney scarring?

The aim of the study reported here was to determine whether kidney scarring after urinary tract infections (UTI) in children can be prevented and to identify the risk factors for developing scars. We identified children in the Northern health region of the UK who had been seen to develop scars, identified as new defects on dimercapto-succinic acid (DMSA) scanning. Risk factors were sought by reviewing case-notes and interviews with parents. Twenty girls were identified whose new scarring was strongly associated with having both vesicoureteric reflux (VUR) and a UTI (p = 0.0001); 19/23 (83%) of kidneys exposed to both of these factors developed scars. Children were much more likely to be febrile (94 vs. 30%, p < 0.0001) or unwell (82 vs. 10%, p < 0.0001) during their earlier UTIs when they were of median age 2.8 years (range 0.3–5.0 years) and did not scar, compared to their later UTIs at age 7.3 years (1.2–12.5 years), when they did scar. However, most patients were treated within 1 day of their symptoms for their early UTIs, compared to a wait ≥7 days for later UTIs (p = 0.001). Being febrile or unwell during a UTI does not predict the development of scars, but prompt treatment appears to prevent scarring in children with VUR.     

膀胱输尿管反流的精准诊治进展

膀胱输尿管反流( VUR)是儿童最为常见的泌尿系统疾病,该病使患儿更易出现肾盂肾炎,是儿童尿路感染后肾脏疤痕形成的最重要的风险因素。到目前为止,对VUR的诊断及治疗仍有很多争议,其争议内容主要是围绕着哪些儿童应该评估反流的有无,以及一旦确诊VUR时哪些儿童又应该接受治疗及接受何种治疗。VUR是一种遗传性疾病,但是该病具有种族差异性、遗传异质性等特点,迄今为止国际上尚没有公认的、一致的主要致病基因。明确不同基因突变所致的VUR的研究,有助于做出肾疤痕形成是先天性还是后天性的判断,从而在临床做出精确诊断及精准治疗。     

Do kidneys outgrow the risk of reflux nephropathy?

Three-quarters of human kidneys have segments that will allow intrarenal reflux if the person is one of the 1% that is also born with vesicoureteric reflux (VUR). It is likely that entry of infected urine into these segments produces permanent damage within just a few days, as it does in piglets and adult pigs. This very rapid course leaves no time for delay in diagnosing and treating urine infections in infants, the group that present the greatest clinical difficulties. It is proposed that the reason why the risk of scarring starts off high and falls to virtually nil by 4 years is not due to maturation that leads to an increased resistance to scarring, but because most vulnerable subjects have already scarred their kidneys in infancy. This proposed model has important implications for clinical management. First, it suggests that current practice identifies scars in children due to urine infection, but prevents few. Second, babies known to have VUR from birth, and protected from scarring with prophylactic antibiotics, will not outgrow their scarring risk by any particular age, but will remain at risk until they outgrow their reflux. This suggests their kidneys need to be protected from scarring until then, perhaps by antibiotic prophylaxis. Third, transplant recipients of any age with refluxing ureteric anastamoses or stents will carry a risk of developing a focal scar if they acquire a urine infection, and may need protection.     

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.     

Primary vesicoureteric reflux and renal damage in the first year of life

We retrospectively examined 93 children (47M/46F) with primary vesicoureteric reflux (VUR) followed for a mean period of 3.5 years. They were divided into two groups. Group A included 34 babies (25M/9F) with a prenatal diagnosis of pelvic dilatation. Mean age at presentation was 12 days and no urinary tract infection (UTI) occurred before our first examination. VUR was unilateral in 21 (62%) patients and bilateral in 13 (38%). It was mild (grades I–III) in 12 (25%) refluxing renal units (RRU) and severe (grades IV–V) in 35 (75%). Renal damage (RD) was present, at diagnosis, in 40 (85%) RRU. There was a greater prevalence of abnormal kidneys in male units (88%) than in female units (75%). Group B included 59 infants (22M/37F) less than 1 year old with UTI. The mean age at first examination was 7.6 months. VUR was unilateral in 32 (54%) infants and bilateral in 27 (46%), mild in 60 (70%) RRU and severe in 26 (30%). At diagnosis, 54 (63%) RRU presented RD, which was more common in females (66%) than in males (44%). Our study confirms that primary VUR associated with prenatal hydronephrosis usually affects males and is severe. VUR diagnosed after UTI, instead, is more common in females and is frequently mild. Although in the first type of reflux RD is often present at diagnosis, then probably congenital, it may always progress after UTI; hence the importance of early diagnosis and careful follow-up in each infant with primary VUR. Received: 9 August 1999 / Revised: 3 April 2000 / Accepted: 7 July 2000     

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.     

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.     

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 [27]. 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.     

Summary of recent AUA guidelines for the management of vesicoureteral reflux in children

VUR is a common condition and it is a predisposing factor for pyelonephritis, and reflux nephropathy, which can cause end stage renal disease in children. Given the consequences and sequelae of UTI and VUR, and due to lack of consensus regarding management of this common condition, the American Urological Association (AUA) developed treatment guidelines for children with VUR in 1997 and 2012 to help physicians better manage children with VUR. In this review, the summary of the 1997 and 2012 AUA guidelines are discussed with a focus on the 2012 report. Recommendations about evaluation and management of children under and above one year with VUR, with and without bladder/bowel dysfunction, screening of siblings of patients with VUR, screening of the neonate/infant with prenatal hydronephrosis, and follow up of the children with VUR are discussed in this review. The identification and management of VUR in these groups, provide the potential opportunity to prevent renal damage and decrease the risk of UTI and pyelonephritis. According to these guidelines, risk assessment of renal injury/scarring in the individual patient based upon clinical factors is critical, and interventions should be appropriate to the risk profile. Informing families and healthcare providers of the potential risk of pyelonephritis and renal scarring and allowing them to participate in decision making is considered important.     

The etiology of renal scars in infants with pyelonephritis and vesicoureteral reflux

We aimed to investigate, by means of dimercaptosuccinic acid (DMSA) scan, the relations between vesicoureteral reflux (VUR) and its degree, pyelonephritis during infancy, and renal parenchymal findings. Seventy-four infants with pyelonephritis, 44 girls and 30 boys (mean age at their first pyelonephritic episode 4.12 months, median 3 months), were enrolled in the study. Voiding cystourethrography (VCU) and ultrasonography (US) were performed within 6 weeks following the infection. DMSA was performed at least 4 months after the urinary tract infection (UTI). The renal parenchymal pathology was defined as focal or multifocal defects or as a split renal uptake of less than 45%. DMSA scintigraphy revealed that 19% (14/74) of the children had renal damage. Renal parenchymal findings were observed only when VUR was present, and its grade was above 3/5. No abnormality was found in 51 renal units without reflux, 9 with VUR grade 1/5, and 54 with grade 2/5. Renal pathology was observed in 9/24 renal units with VUR grade 3, 3/8 with grade 4, and 2/2 with grade 5. No correlation was found between renal parenchymal defects and clinical presentation of the pyelonephritis, type of the microorganism, presence of bacteremia, or the number of recurrent infections. In adequately treated infants, renal damage is probably due to a reflux-associated, preexisting, congenital renal parenchymal pathology and not to the inflammatory process. We suggest that DMSA scintigraphy should not be performed routinely in every infant with UTI and should be reserved primarily for children with VUR grade 3 and above. Received: 17 February 1999 / Revised: 30 June 1999 / Accepted: 7 July 1999     

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.