Evaluation of Renal Parenchyma in Children by DMSA Scientigraphy, X-ray Computed Tomography and Intravenous Urography

ABSTRACT. The demonstration of diminished or scarred renal parenchyma in children is often the decisive factor in determining the future management of children with urinary tract malformations. Renal scintigraphy using technetium 99m-labelled dimercaptosuccinic acid (DMSA), computed tomography (CT) and intravenous urography (IU) were used to evaluate the renal parenchyma prior to ureter re-implantation in a series of 13 children. Their ages ranged from 5 months to 3 years 8 months. The indication for operation was ureteric reflux in 8 children and distal ureteric stenosis in 5. CT was performed on a Toshiba TCT-80 scanner. Renal scintigraphy was performed 3 hours after intravenous injection of DMSA. Compared with IU, DMSA imaging gave more information about the renal parenchyma in 6 children, gave equal information in 6 and less in 1. Compared with CT, DMSA imaging gave more information in 2 children, was equally informative in 8 and less so in 3. Accordingly, DMSA imaging was judged to be more sensitive than IU and as sensitive as CT. DMSA imaging can be used both for the initial evaluation and for follow-up assessment of renal parenchymal damage.     

Imaging of pyelonephritis

Objective. Accurate diagnosis of pyelonephritis using clinical and laboratory parameters is often difficult, especially in children. The main aims of this prospective study were to compare the value of different imaging techniques [renal sonography, cortical scintigraphy with technetium-99m dimercaptosuccinic acid (^99mTc DMSA) and computed tomography (CT)] in detecting renal involvement in acute urinary tract infections and to determine the sensitivity of DMSA scans for permanent renal scars 6 months later. Materials and methods. Between February 1992 and January 1993, 55 children admitted to our pediatric unit with febrile symptomatic urinary tract infections were eligible for analysis. Ultrasonography (US), DMSA scanning and micturating cystourethrography were performed in every case. Only 18 children underwent CT. A second DMSA scan was performed in 48 children a mean of 7.5 months after the first. Results. US abnormalities were found in 25 children (45 %). The first DMSA scan showed a parenchymal aspect suggestive of pyelonephritis in 51 patients (93 %). Among the 18 patients studied by CT, 14 had abnormalities. Normal US findings did not rule out renal parenchymal involvement. Scintigraphy appeared to be more sensitive than CT for renal involvement. The frequency and degree of initial renal parenchymal damage seemed to correlate with vesicoureteral reflux, but the most severe initial parenchymal defects were not associated with marked clinical or laboratory manifestations. Repeat DMSA scans, performed on 45 kidneys with abnormalities at the first examination, showed resolution in 19, improvement in 16, persistence in 8 and deterioration in 2. The prevalence of vesicoureteral reflux was not higher in patients with renal scarring on the second DMSA scan than in patients whose scans showed an improvement. Conclusion. DMSA scans should be considered as a reference in the detection and follow-up of renal scarring associated with acute urinary tract infection as this technique is more sensitive than US and CT, the latter being unsuitable because it entails radiation exposure and sedation of patients. Received: 9 February 1996 Accepted: 14 February 1996     

99mTc dimercaptosuccinic acid (DMSA) scan as first investigation of urinary tract infection.

A total of 115 children under 5 years who presented with a first symptomatic urinary tract infection and who had a 99mTc dimercaptosuccinic acid (DMSA) scan were studied to assess its value and compare the findings with those of other imaging techniques. Renal cortical defects were detected in 65 kidneys by DMSA scan, intravenous urogram, and ultrasound scan combined; 62 (95%) being seen on DMSA scan. The finding of reflux on micturating cystourethrography showed a highly significant correlation with renal defects seen on DMSA scanning, a less close but still significant correlation with abnormalities on intravenous urography, but none with ultrasound scan findings. The sensitivity of the DMSA scan in screening for all grades of reflux is estimated as 0.66, which is higher than that previously reported for the intravenous urogram or ultrasound scan. DMSA scans were less likely to miss grade 3 reflux than the other two methods. DMSA scans are more useful than other upper renal tract imaging techniques in detecting renal defects. Consideration should be given to their use as a first investigation in place of routine intravenous urograms. Ultrasound scans alone will overlook potentially serious urinary tract abnormalities.     

Randomised controlled trial of three day versus 10 day intravenous antibiotics in acute pyelonephritis: effect on renal scarring.

BACKGROUND: Acute pyelonephritis often leaves children with permanent renal scarring. AIMS: To compare the prevalence of scarring following initial treatment with antibiotics administered intravenously for 10 or three days. METHODS: In a prospective two centre trial, 220 patients aged 3 months to 16 years with positive urine culture and acute renal lesions on initial DMSA scintigraphy, were randomly assigned to receive intravenous ceftriaxone (50 mg/kg once daily) for 10 or three days, followed by oral cefixime (4 mg/kg twice daily) to complete a 15 day course. After three months, scintigraphy was repeated in order to diagnose renal scars. RESULTS: Renal scarring developed in 33% of the 110 children in the 10 day intravenous group and 36% of the 110 children in the three day group. Children older than 1 year had more renal scarring than infants (42% (54/129) and 24% (22/91), respectively). After adjustment for age, sex, duration of fever before treatment, degree of inflammation, presence of vesicoureteric reflux, and the patients' recruitment centres, there was no significant difference between the two treatments on renal scarring. During follow up, 15 children had recurrence of urinary infection with no significant difference between the two treatment groups. CONCLUSION: In children with acute pyelonephritis, initial intravenous treatment for 10 days, compared with three days, does not significantly reduce the development of renal scarring.     

Intra- and interobserver variability in interpretation of DMSA scans using a set of standardized criteria

A set of criteria was developed to standardize assessment of DMSA renal scintigraphy which were performed to evaluate children for acute pyelonephritis and renal scarring. This study was undertaken to assess intra- and interobserver variability in the interpretation of DMSA renal scintigraphy using these criteria. Renal contours and parenchyma were assessed in three zones. Contours were assessed as normal or abnormal and parenchymal defects were evaluated in terms of character, shape and degree in three regions (upper and lower pole and midzone). Two nuclear medicine physicians blindly reviewed 57 DMSA scintigraphy on two occasions each. Disagreement of each observer's evaluation of the same scintigraphy on two different occasions was described as intraobserver variability, and the comparison between readings by each of the two observers was described as interobserver variability. High levels of intra-(95.9% and 90.6% respectively,p<0.05) and interobserver agreement (84.4%,p<0.05) were demonstrated. There were minor differences in inconsistencies between the two kidneys or different kidney zones. We conclude that standardization of criteria resulted in higher intra- and interobserver consistency in interpretation of DMSA scintigraphy.     

Randomised trial of oral versus sequential intravenous/oral cephalosporins in children with pyelonephritis

The hypothesis was tested that oral antibiotic treatment in children with acute pyelonephritis and scintigraphy-documented lesions is equally as efficacious as sequential intravenous/oral therapy with respect to the incidence of renal scarring. A randomised multi-centre trial was conducted in 365 children aged 6 months to 16 years with bacterial growth in cultures from urine collected by catheter. The children were assigned to receive either oral ceftibuten (9 mg/kg once daily) for 14 days or intravenous ceftriaxone (50 mg/kg once daily) for 3 days followed by oral ceftibuten for 11 days. Only patients with lesions detected on acute-phase dimercaptosuccinic acid (DMSA) scintigraphy underwent follow-up scintigraphy. Efficacy was evaluated by the rate of renal scarring after 6 months on follow-up scintigraphy. Of 219 children with lesions on acute-phase scintigraphy, 152 completed the study; 80 (72 females, median age 2.2 years) were given ceftibuten and 72 (62 females, median age 1.6 years) were given ceftriaxone/ceftibuten. Patients in the intravenous/oral group had significantly higher C-reactive protein (CRP) concentrations at baseline and larger lesion(s) on acute-phase scintigraphy. Follow-up scintigraphy showed renal scarring in 21/80 children treated with ceftibuten and 33/72 with ceftriaxone/ceftibuten (p = 0.01). However, after adjustment for the confounding variables (CRP and size of acute-phase lesion), no significant difference was observed for renal scarring between the two groups (p = 0.2). Renal scarring correlated with the extent of the acute-phase lesion (r = 0.60, p < 0.0001) and the grade of vesico-ureteric reflux (r = 0.31, p = 0.03), and was more frequent in refluxing renal units (p = 0.04). The majority of patients, i.e. 44 in the oral group and 47 in the intravenous/oral group, were managed as out-patients. Side effects were not observed. From this study, we can conclude that once-daily oral ceftibuten for 14 days yielded comparable results to sequential ceftriaxone/ceftibuten treatment in children aged 6 months to 16 years with DMSA-documented acute pyelonephritis and it allowed out-patient management in the majority of these children.     

Randomised controlled trial of three day versus 10 day intravenous antibiotics in acute pyelonephritis: effect on renal scarring

BACKGROUND—Acute pyelonephritis often leaves children with permanent renal scarring.AIMS—To compare the prevalence of scarring following initial treatment with antibiotics administered intravenously for 10 or three days.METHODS—In a prospective two centre trial, 220 patients aged 3 months to 16 years with positive urine culture and acute renal lesions on initial DMSA scintigraphy, were randomly assigned to receive intravenous ceftriaxone (50 mg/kg once daily) for 10 or three days, followed by oral cefixime (4 mg/kg twice daily) to complete a 15 day course. After three months, scintigraphy was repeated in order to diagnose renal scars.RESULTS—Renal scarring developed in 33% of the 110 children in the 10 day intravenous group and 36% of the 110 children in the three day group. Children older than 1 year had more renal scarring than infants (42% (54/129) and 24% (22/91), respectively). After adjustment for age, sex, duration of fever before treatment, degree of inflammation, presence of vesicoureteric reflux, and the patients'' recruitment centres, there was no significant difference between the two treatments on renal scarring. During follow up, 15 children had recurrence of urinary infection with no significant difference between the two treatment groups.CONCLUSION—In children with acute pyelonephritis, initial intravenous treatment for 10 days, compared with three days, does not significantly reduce the development of renal scarring.     

Vesico-ureteric reflux and other risk factors for renal damage: identification of high- and low-risk children

This article reviews the literature with respect to various risk factors for permanent renal damage in children with urinary tract infection. Vesico-ureteric reflux is an important risk factor, but renal damage can occur in the absence of reflux. Renal damage does not always occur in the presence of gross reflux. Renal scars always develop at the same site as a previous infection in the kidney. Recurrent pyelonephritis and delay in therapy increase the likelihood of renal damage, although it is not known how long a delay is dangerous to the human kidney. Recent studies using ^99mtechnetium-dimercaptosuccinic acid (DMSA) scintigraphy have not confirmed the findings of previous studies showing that children below 1 y of age are more vulnerable to renal damage. It is more likely that all children run the risk of renal scarring in cases of acute pyelonephritis. The role of bladder pressure is still not entirely understood. Therefore more studies are needed in order to determine the relationship between high voiding pressures in some, otherwise healthy, children with urinary tract infection and renal scarring. The importance of bacterial virulence in the development of renal scarring is unclear. DMSA scintigraphy and voiding cystourethrography are the most reliable tools for identifying children at risk of renal scarring. As a single method DMSA scintigraphy appears to be better than voiding cystourethrography.     

Vesico-ureteric reflux and other risk factors for renal damage: identification of high- and low-risk children

This article reviews the literature with respect to various risk factors for permanent renal damage in children with urinary tract infection. Vesico-ureteric reflux is an important risk factor, but renal damage can occur in the absence of reflux. Renal damage does not always occur in the presence of gross reflux. Renal scars always develop at the same site as a previous infection in the kidney. Recurrent pyelonephritis and delay in therapy increase the likelihood of renal damage, although it is not known how long a delay is dangerous to the human kidney. Recent studies using 99mtechnetium-dimercaptosuccinic acid (DMSA) scintigraphy have not confirmed the findings of previous studies showing that children below 1 y of age are more vulnerable to renal damage. It is more likely that all children run the risk of renal scarring in cases of acute pyelonephritis. The role of bladder pressure is still not entirely understood. Therefore more studies are needed in order to determine the relationship between high voiding pressures in some, otherwise healthy, children with urinary tract infection and renal scarring. The importance of bacterial virulence in the development of renal scarring is unclear. DMSA scintigraphy and voiding cystourethrography are the most reliable tools for identifying children at risk of renal scarring. As a single method DMSA scintigraphy appears to be better than voiding cystourethrography.     

Uncomplicated duplex kidney and DMSA scintigraphy in children with urinary tract infection

Background Renal duplication is the most common malformation of the urinary tract and is frequently seen among children with urinary tract infection (UTI). Objective To evaluate problems in the interpretation of dimercaptosuccinic acid (DMSA) scintigraphy and to establish the range of relative function in uncomplicated unilateral duplication. Materials and methods Retrospective analysis of 303 children less than 2 years of age with first time non-obstructive urinary tract infection investigated by both urography and DMSA scintigraphy. At DMSA scintigraphy, renal lesions and/or relative function below 45% was considered abnormal. Urography was used as reference for the diagnosis of duplication. Results Duplex kidneys were found in 22 of 303 patients (7%). Of the 16 children with unilateral duplication, 10 had bilaterally undamaged kidneys with a range of relative function varying between 51% and 57% in the duplex kidney. In two of the children with unilateral duplication the imaging results were discordant. Conclusion There was risk of underdiagnosis as well as overdiagnosis of renal damage at scintigraphy. Although it is important to be aware of this risk, the rate of misinterpretation was low. A range of 51% to 57% can be used as the limit for normality of the relative function of a unilateral duplex kidney.     

Renal scintigraphy using technetium dimercaptosuccinic acid in the diagnosis of pyelonephritis in children: study of 17 cases

OBJECTIVE: To determine whether the presence of abnormal results in DMSA renal scintigraphy indicates pyelonephritis. METHODS: We performed the washout test in 17 children with urinary tract infection, as a criterion standard, to locate the infection site. All the children underwent DMSA renal scintigraphy in the acute phase of the disease. The results were analyzed by the chi-square test or Fisher test. RESULTS: DMSA renal scintigraphy revealed changes in all five cases of pyelonephritis, suggesting acute kidney involvement. On the other hand, only one child with cystitis (total = 12 cases) had abnormal results in renal scintigraphy. Sensitivity and specificity were 100% and 92%, respectively. CONCLUSION: DMSA renal scintigraphy is a sensitive method for the diagnosis of pyelonephritis in children.     

Ordering of renal tract imaging by paediatricians after urinary tract infection

AIM: To describe paediatricians' reported ordering of renal tract imaging of children following urinary tract infection. METHODS: This is a piloted self-administered survey. A total of 354 randomly sampled practising paediatricians in Australia participated in the survey. The survey included 12 clinical scenarios that varied with age, gender and fever. Respondents indicated their likelihood of ordering renal ultrasound, micturating cystourethrogram (MCU) and dimercaptosuccinic acid scan (DMSA) from 0 to 100%. RESULTS: Response rate was 74.6% (264/354). For all clinical scenarios the median probability of ordering an ultrasound was 100% with little variability. For children aged 2 months, likelihood of ordering an MCU was 100%, with little variability, but was 70% for 3-year-olds with fever (45% without fever), and 5% for 6-year-olds with very large variability. Median likelihood of ordering a DMSA was 80% at 2 months, 60% at 3 years and 20% at 6 years (40%, 15%, 5% without fever, respectively). Variability was large for all scenarios and DMSA ordering. Child gender did not influence ordering practices. CONCLUSIONS: Renal tract imaging practice across paediatricians shows consistent, approximately 100% use of the least invasive modality, ultrasound. In contrast, there is considerable variation in the reported ordering of the more invasive tests MCU and DMSA. Doctors order these tests more in younger children and when fever is present.     

Resolution of cortical lesions on serial renal scans in children with acute pyelonephritis

Background The ideal time for distinguishing a renal scar from acute inflammatory lesions by renal DMSA scintigraphy remains controversial. Objective To determine the time needed for resolution of lesions after acute pyelonephritis. Materials and methods A total of 105 children with acute pyelonephritis underwent renal sonography, voiding cystourethrography and baseline DMSA scintigraphy. Two subsequent scans were performed during the 6th and 12th months in patients with abnormal findings on the previous scan. Results The baseline DMSA scintigraphy revealed cortical lesions in 37 patients. At 6 months, 13 patients (38.2%) were found to have cortical lesions. At 12 months, 6 patients (17.6%) were found to have persistent renal cortical lesions. The resolution rates for lesions detected on the first scan were 61.8% and 82.4% on the 6- and 12-month scans, respectively. Vesicoureteric reflux, and bilaterality or multifocality were not relevant for resolution of lesions. Female gender seemed to be associated with a higher persistence rate. Conclusions The renal cortical defects present at 6 months have a high rate of resolution later during follow-up. DMSA scintigraphy performed 12 months after the infection provides more reliable data regarding persistence of renal cortical lesions.     

Post-pyelonephritic renal scars are not associated with high voiding pressures

ObjectiveThe aim of this study was to evaluate whether renal scars and vesicoureteral reflux (VUR) are associated with bladder dysfunction in children after first clinical pyelonephritis.Patients and methodsSixty-four children were evaluated with urodynamics and voiding cystourethrography at a median of 8 weeks after their first episode of clinical pyelonephritis. All patients had ultrasonography and dimercaptosuccinic acid (DMSA) scintigraphy during the infection. After 2 years, DMSA scintigraphy was repeated in 58 patients. Re-infections were recorded.ResultsOveractive detrusor was found in 27 (42%) patients. There was no significant difference in the incidence of overactive detrusor between boys and girls. The maximal voiding pressure was higher in boys (median 92.5, range 48–191 cmH₂O) than in girls (median 82, range 37–150 cmH₂O) (P = 0.0117). Thirty-one (48%) patients had renal defects in scintigraphy during the infection. Ultimately, 12 patients (21%) developed renal scars; 11 patients (17%) had VUR. Renal defects in DMSA scintigraphy and the presence of VUR were not associated with overactive detrusor or high voiding pressures.ConclusionOveractive detrusor is a common finding after first episode of pyelonephritis. The dysfunction may explain the development of urinary tract infections in some children. There were no differences in the incidence of overactive detrusor or voiding pressures in patients with and without VUR, or in those with and without renal defects on DMSA scintigraphy. Urodynamic study is not a primary investigation in pyelonephritic children.     

Late renal sequelae in intravenously treated complicated urinary tract infection

Background

The treatment of complicated urinary tract infection in children is still a matter of debate. In our hospital, antimicrobial treatment is initiated intravenously, and the duration of this treatment is adapted according to the results of a Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy.

Aim

This study was conducted to evaluate retrospectively the frequency and the importance of late renal sequelae when treating intravenously for 7 days those patients with an abnormal acute DMSA.

Methods

A review was conducted of the medical charts of all patients consecutively admitted between 2005 and 2008 with positive urine culture and clinical and biological evidence of complicated urinary tract infection (UTI).

Results

There were 144 patients (59 %) with abnormal early DMSA scintigraphy and 98 (41 %) with normal scintigraphy. The median duration of intravenous treatment was 7.0 days in the children with DMSA lesions and 5.0 days in those without lesions. Obvious renal sequelae were observed on late DMSA scintigraphy in 4 (6 %) out of the 65 patients with an abnormal early DMSA who came back for control scintigraphy.

Conclusion

Sequelae of acute DMSA lesions observed during complicated UTI treated 7 days intravenously were infrequent. Whether the mode and duration of antimicrobial treatment might explain the low rate of sequelae remains to be demonstrated.     

Procalcitonin is a marker of severity of renal lesions in pyelonephritis

OBJECTIVE: In an attempt to differentiate acute pyelonephritis from lower urinary tract infection (UTI), we measured serum procalcitonin levels, a recently described marker of infection. We compared it with other commonly used inflammatory markers and evaluated its ability to predict renal involvement as assessed by dimercaptosuccinic acid (DMSA) scintigraphy. METHODS: Serum C-reactive protein, leukocyte counts, and procalcitonin levels were measured in 80 children, 1 month to 16 years of age, admitted for suspected pyelonephritis. Renal involvement was assessed by 99mTe-DMSA scintigraphy in the first 5 days after admission. The examination was repeated at least 3 months later if the first result was abnormal. RESULTS: In lower UTI, the mean procalcitonin (PCT) was 0.38 micrograms/L +/- 0.19 compared with 5.37 micrograms/L +/- 1.9 in pyelonephritis. In these two groups, respectively, leukocyte counts were 10939/mm3 +/- 834 and 17429/mm3 +/- 994, and C-reactive protein (CRP) levels were 30.3 mg/L +/- 7.6 and 120.8 mg/L +/- 8.9. When inflammatory markers were correlated to the severity of the renal lesion as ranked by DMSA scintigraphy, we found a highly significant correlation with plasma levels of PCT, but borderline significance with CRP and none with leukocyte counts. Patients without vesicoureteral reflux had a mean PCT of 5.16 micrograms/L +/- 2.33, which was not significantly different from that in patients with reflux who had a mean PCT of 5.76 micrograms/L +/- 3.49. For the prediction of renal lesions at admission, CRP had a sensitivity of 100% and a specificity of 26.1%. The sensitivity and specificity of PCT were 70.3% and 82.6%, respectively. CONCLUSION: We conclude that serum PCT levels were increased significantly in children with febrile UTI when renal parenchymal involvement (assessed by DMSA scintigraphy) was present and allowed for prediction of patients at risk of severe renal lesions.     

Early 99mTc dimercaptosuccinic acid (DMSA) scintigraphy in symptomatic first-time urinary tract infection

During a 2 year period, 175 children below 6 years of age (median 0.4 year) with non-obstructive symptomatic urinary tract infection were studied by ^99mTc dimercaptosuccinic acid (DMSA) scintigraphy. DMSA scintigraphy was performed at a median of 10 days after the start of treatment and was abnormal in 73 children (42%), equivocal in 29 (16%) and normal in 73 (42%). Reflux was seen in 27% of all children and in 38% of the renal units that were abnormal at DMSA scintigraphy. A decreasing frequency of abnormalities at DMSA scintigraphy was seen within the first 14 days after the start of treatment. C-reactive protein and grade of reflux correlated significantly with abnormal DMSA studies. To demonstrate renal involvement in acute urinary tract infection, DMSA scintigraphy should be performed within days after the start of treatment. It is noteworthy that reflux was seen in less than half of renal units with abnormal DMSA scintigraphy.     

Renal dysplasia in infants: Apperance on99mTc DMSA scintigraphy

Infantile renal dysplasias, including multicystic dysplastic kidneys (MCDK), are reported rarely to accumulate radiopharmaceuticals on renal scintigraphy.^99mTc DMSA is a highly sensitive tracer for detecting functioning renal cortical tissue and may be more suited to studying renal dysplasia than^99mTc DTPA. We reviewed the ultrasound studies and^99mTc DMSA scintigrams of 42 infants (age range 1–12 months) with known or suspected MCDK. Overall, uptake on^99mTc DMSA scintigraphy was evident in 6/41 (15%) dysplastic kidneys. Of the 18 patients who underwent nephrectomy, histopathological examination revealed that uptake correlated closely with the presence of mature renal cortical tissue in the affected kidney. Our study shows that a small, but significant number of MCDK will show low-grade uptake on DMSA scintigraphy. This finding may be relevant given the reliance placed on renal scintigraphy in planning treatment for infants with suspected MCDK, particularly with the increasing trend for the non-operative management of this condition.     

Extracorporeal lithotripsy in children. Study of its efficacy and evaluation of renal parenchymal damage by DMSA-Tc 99m scintigraphy: a series of 39 children]

AIM: The objectives of the study were to confirm the efficacy of extracorporeal shock wave lithotripsy (ESWL) in infants and children and to evaluate potential long-term renal parenchymal damage by 99m Tc DMSA renal scan. MATERIALS AND METHODS: Between November 1989 and November 1997, 39 children between 10 months and 17-1/2 years of age (average: 7 years) were treated by extracorporeal shock wave lithotripsy for kidney or ureteral stones with a Sonolith 3000 lithotriptor (Technomed Corp). Forty-six stones were treated. Eight metabolic and 11 urological abnormalities were identified. The evaluation of the treatment and its consequences were based on a clinical examination, conventional imaging and a DMSA renal scan performed 24 h before extracorporeal shock wave lithotripsy and at least 6 months after treatment. RESULTS: Treatment was successful (stone fragmented and eliminated) in 84.6% at 3 months after one to four sessions. Sixty-one sessions were necessary and two patients underwent open surgery for failed extracorporeal shock wave lithotripsy. Three recurrences were also retreated. At long term follow-up (6 months to 8 years) no incidents of high blood pressure were observed, nor parenchymal lesions imputable to extracorporeal shock wave lithotripsy. CONCLUSIONS: The efficacy of the extracorporeal shock wave lithotripsy for children is proven. This study also confirms the innocuousness of extracorporeal shock wave lithotripsy for renal parenchyma even in infants. However, long term follow-up and further evaluation with the other categories of lithotriptors are necessary to make definitive conclusions.     

Renal scarring after acute pyelonephritis.

Seventy six children, 18 boys and 58 girls, aged 0-15.9 (median 1.0) years, with acute pyelonephritis were prospectively studied with a technetium-99m dimercaptosuccinic acid (DMSA) scan during infection and two months later. Fifty nine of these children were also studied two years after the infection. Seventeen children with a normal DMSA scan during infection or at two months after infection, or both, were not investigated by a DMSA scan at two years after acute pyelonephritis. A micturition cystourethrogram was performed in all the children after two months. Changes on the DMSA scan were found in 65 (86%) children during acute pyelonephritis, in 45 (59%) children at two months, and in 28 (37%) children at two years after infection. Vesicoureteric reflux (VUR) was found in 19 (25%) children at two months. Renal scarring was significantly correlated with the presence of gross VUR and recurrent pyelonephritis, but 62% of the scarred kidneys were drained by non-refluxing ureters. Children with scars were older at the time of acute pyelonephritis than those without scars but no difference was found between the groups with regard to duration of illness, levels of C reactive protein and maximum white cell count, glomerular filtration rate, nor renal concentration capacity at the time of infection. It is concluded that renal scarring after acute pyelonephritis in children is more common than has been previously thought. Although children with gross VUR and recurrent pyelonephritis are at the greatest risk, renal scarring is more often seen without these risk factors.