Voiding cystourethrography as a predictor of reflux nephropathy in children with urinary-tract infection

Contrast-enhanced voiding urosonography in the diagnosis of intrarenal reflux

PURPOSE

Although contrast-enhanced urosonography (ceVUS) has shown capable diagnostic accuracy for the diagnosis of vesicoureteral reflux (VUR) in children, the ability of ceVUS to detect intrarenal reflux (IRR) is considered limited. The purpose of our study is to assess the ability of ceVUS to detect IRR as well as its association with age, gender, and the grade of VUR.

METHODS

This study included 5153 children who were referred to our clinic for ceVUS. All children underwent sonographic examinations, which were performed on a LOGIQ S8 machine equipped with dedicated software for contrast-enhanced studies with harmonic imaging. Standard ultrasound of the urinary tract was followed by bladder catheterisation and instillation of physiological normal saline and the US contrast medium (SonoVue^®, Bracco).

RESULTS

VUR was diagnosed by ceVUS in 1959 out of 5153 children (38%), of whom IRR was found in 233 of 1959 children (11.9%). A total of 285 ureteral units showing IRR were found. High grades of VUR (IV + V) with IRR were found in a total of 235 of 285 (82.81%) renal units. Bilateral IRR was found in 53 patients, usually with a high-grade VUR on both sides. Most children had VUR grade IV, predominantly those < 12 months. The younger the child, the higher the likelihood of higher-grade VUR (p = 0.02).

CONCLUSION

ceVUS, combined with harmonic imaging and second-generation ultrasound contrast media, enabled IRR detection in almost 12% of our patients with VUR. IRR is most commonly found in children under 1 year of age with VUR grades IV and V.

Intrarenal reflux, an overlooked entity - retrospective analysis of 1,166 voiding cysturethrographies in children

BACKGROUND

The significance of intrarenal reflux as a risk factor for renal scarring and hypertension has been discussed. Fluoroscopic detection of intrarenal reflux depends on the equipment, the training of the radiologists and the timing of spot film acquisition.

OBJECTIVE

To evaluate the prevalence of intrarenal reflux and its association with age, gender, grade of vesico-uretero-renal reflux and the renal segments affected.

MATERIALS AND METHODS

We retrospectively analysed 1,166 voiding cysturethrographies. Patients' ages ranged from 1 day old to 19 years old. Vesico-uretero-renal reflux was detected in 209 female and 164 male patients using a standardised technique with digital pulsed fluoroscopy. The point in time and grade of reflux were documented with spot films. All radiographs showing reflux were assessed for the occurrence of intrarenal reflux.

RESULTS

Intrarenal reflux was detected in 41 of 373 (11%) patients with vesico-uretero-renal reflux. Unilateral intrarenal reflux was found in 30 patients and bilateral in 11. The left kidney was more frequently affected than the right (31 versus 21). Only patients younger than 9 years of age were affected (mean age: 1.6 years, median: 0.8 years). Intrarenal reflux was independent of gender and was most frequently observed in grade IV reflux (59.6%) and less often in grade V (23.1%) and grade III (17.3%).

CONCLUSION

Intrarenal reflux in this study was detected in 11% of patients with vesico-uretero-renal reflux, predominantly with reflux grade IV and in patients younger than 4 years old.

Predictors of Renal Dysfunction in Adults with Childhood Vesicoureteral Reflux after Long-Term Follow-Up

BACKGROUND:

Triad of childhood vesicoureteral reflux (VUR), urinary infection (UTI) and renal scarring might initiate potentially serious consequences that lead to renal dysfunction manifested at the second or third decade of life.

AIM:

To identify the risk factors predictive for renal dysfunction in adults with primary VUR after long-term follow-up.

METHODS:

We evaluated the records of 101 children (94.1% female, 5.9% male) at a median age of 5.2 ± 2.3 years (1-12 years), suffering from UTI and VUR. The patients were interviewed after mean 21 years from the first episodes of VUR (8 to 32 years). Renal function was determined from the estimated glomerular filtration rate (eGFR).

RESULTS:

Renal scarring was detected in 68.3% out of 82 patients and bilateral one in 7.3% patients. Linear regression analysis revealed that presence of proteinuria (B = -33.7, p=0.0001), the greater number of years from VUR diagnosis (B = -1.6, p = 0.002) and renal scarring (B = -14.8, p = 0.005) appeared as independent predictors of reduced global eGFRcreat. The same variables plus microalbuminuria (B = -1.0, p = 0.012) appeared as independent predictors of reduced global eGFRcreat-cys. Bilateral scarring (OR=25.5, p = 0.003) appeared as independent predictor of greater risk for CKD assessed using eGFRcreat while greater number of years from VUR diagnosis (OR = 1.7, p = 0.092), microalbuminuria (OR = 1.3, p = 0.047) and again bilateral scarring (OR = 31.3, p = 0.040) appeared as predictors of risk for CKD assessed using eGFRcreat-cys.

CONCLUSION:

Identification of those with an increased risk of progression to CKD should be the goal in all patients with childhood VUR. Their systematic follow-up should be till adulthood and older age.

Human immunodeficiency virus and urinary tract infections in children

This was a retrospective study of HIV-infected children aged 0-12 years attending the King Edward VIII Hospital in Durban, South Africa over a 5-year period (January 1996 to December 2001) with culture-proven urinary tract infection (UTI). UTI was defined as the presence of a single bacterial growth of >10(5) colony-forming units/ml in a clean-catch, mid-stream urine sample or >10(3) organisms/ml in a catheter or suprapubic aspirate of urine. HIV/AIDS was diagnosed in accordance with World Health Organization and/or Centers for Disease Control criteria. Comparison between HIV-positive and HIV-negative children with UTI was done using the chi2 and Wilcoxon rank sum tests. Of the 55 children recruited into the study, 29 (52.1%) were HIV-positive and 26 (47.3%) HIV-negative. Escherichia coli was isolated in 50 (87.2%) children. Clinical presentation, aetiological agents, response to therapy and renal function were similar in both groups. This study showed no significant impact of HIV/AIDS on the presentation of UTI in children.

Modeling the detectability of vesicoureteral reflux using microwave radiometry

We present the modeling efforts on antenna design, frequency selection and receiver sensitivity estimation to detect vesicoureteral reflux (VUR) using microwave (MW) radiometry as warm urine from the bladder maintained at fever range temperature using a MW hyperthermia device reflows into the kidneys. The radiometer center frequency (f(c)), frequency band (Deltaf) and aperture radius (r(a)) of the physical antenna for kidney temperature monitoring are determined using a simplified universal antenna model with a circular aperture. Anatomical information extracted from the computed tomography (CT) images of children aged 4-6 years is used to construct a layered 3D tissue model. Radiometric antenna efficiency is evaluated in terms of the ratio of the power collected from the target at depth to the total power received by the antenna (eta). The power ratio of the theoretical antenna is used to design a microstrip log spiral antenna with directional radiation pattern over f(c) +/- Deltaf/2. Power received by the log spiral from the deep target is enhanced using a thin low-loss dielectric matching layer. A cylindrical metal cup is proposed to shield the antenna from electromagnetic interference (EMI). Transient thermal simulations are carried out to determine the minimum detectable change in the antenna brightness temperature (deltaT(B)) for 15-25 mL urine refluxes at 40-42 degrees C located 35 mm from the skin surface. Theoretical antenna simulations indicate maximum eta over 1.1-1.6 GHz for r(a) = 30-40 mm. Simulations of the 35 mm radius tapered log spiral yielded a higher power ratio over f(c) +/- Deltaf/2 for the 35-40 mm deep targets in the presence of an optimal matching layer. Radiometric temperature calculations indicate deltaT(B) 0.1 K for the 15 mL urine at 40 degrees C and 35 mm depth. Higher eta and deltaT(B) were observed for the antenna and matching layer inside the metal cup. Reflection measurements of the log spiral in a saline phantom are in agreement with the simulation data. The numerical study suggests that a radiometer with f(c) = 1.35 GHz, Deltaf = 500 MHz and detector sensitivity better than 0.1 K would be the appropriate tool to noninvasively detect VUR using the log spiral antenna.

Ultrasonography as predictor of permanent renal damage in infants with urinary tract infection

AIM

To evaluate the ability of ultrasound (US) in infants (<1 year) with acute urinary tract infection (UTI), to identify those with permanent renal damage (PRD) at scintigraphy 1 year later.

METHODS

US, dimercaptosuccinic acid scintigraphy and voiding cystourethrography were performed in 191 infants.

RESULTS

US was abnormal in 46 infants (24%). PRD was found in 46 infants (24%); 19 of these had abnormal US (sensitivity 41%). In 145 infants without PRD, 27 had abnormal US (specificity 81%). Dilating reflux or verified obstruction occurred in 21 (11%) infants, of whom 18 (86%) had PRD while 28 of 170 (16%) without such diagnoses had PRD. Of 16 infants with dilating reflux, 9 (sensitivity 56%) had abnormal US and 14 (88%) PRD. Dilatation at US was seen in 27 children; 7 of these had dilating reflux and 5 verified obstruction.

CONCLUSION

US performed in association with acute UTI had limited ability to identify children with PRD at (99m)Tc-dimercaptosuccinic acid (DMSA) 1 year later, although abnormal renal size was a strong indicator of renal damage. The ability of US to identify children with dilating reflux was also limited. However, once detected at US, dilatation of the urinary tract was associated with dilating reflux or obstruction in half of the cases. Our study confirms that dilating reflux and obstruction are strong indicators of PRD but only half of those who developed PRD had such diagnoses.

Intravenous contrast-enhanced dynamic MR urography: Diagnosis of vesicoureteral reflux during bladder filling with time-signal intensity curves

PURPOSE

To evaluate the time-signal intensity (SI) curves generated from intravenous (IV) gadodiamide-enhanced dynamic magnetic resonance (MR) urographic scans for identifying vesicoureteral reflux (VUR) during bladder filling.

MATERIALS AND METHODS

MR urographic studies of children were retrospectively reviewed, and 52 ureterorenal units of 26 patients (15 females and 11 males, mean age = 5.5 years) who had also undergone voiding cystourethrographic (VCUG) examination were included in this study. The patients were examined on a 1.5T scanner. For functional MR urography and to generate time-SI curves, we used a post IV contrast-enhanced two-dimensional (2D) fast field echo (FFE) sequence (TR = 17 msec, TE = 3.2 msec, flip angle (FA) = 90 degrees ) in the coronal plane. MR urographic time-SI curves that demonstrated a prompt and concave fall of the initial third phase followed by intermittent or constantly increasing SI peaks above the baseline from which the second phase starts were considered to have VUR. We compared the differences in time-SI curves between the control group and patients with VUR during bladder filling.

RESULTS

Twelve ureterorenal units of eight patients (four bilateral and four unilateral) had VUR during bladder filling on VCUG. The time-SI curves of these patients showed intermittent (N = 8 ureterorenal units), and constantly increasing (N = 4 ureterorenal units) SI peaks consistent with VUR. One patient also had bilateral abnormal time-SI curves suggesting VUR despite the normal VCUG study. In the control group, 25 units had normal triphase time-SI curves, six renal units had urinary dilatation with good washout after diuretic injection, and four renal units had upper urinary dilatation without contrast washout, while five renal units did not show any function. None of the patients in the control group revealed distortion in the time-SI curve. The differences in time-SI curves patterns between the control group and patients with VUR during bladder filling were statistically significant (P < 0.001).

CONCLUSION

After a prompt and concave decrease of the initial third phase of the time-SI curve, intermittent spikes or a constant rise in SI above the baseline suggest the existence of VUR.

How does study quality affect the results of a diagnostic meta-analysis?

BACKGROUND

The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies.

METHODS

This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns.

RESULTS

Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations.

CONCLUSION

Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited.

[Primary vesicoureteral reflux treatment in childhood: comparsion of two systematic review]

Many medical practices are being carried out unawares of their efficiency, or of their actual impact on the health of the patients, therefore it is necessary to consider the support of professional recommendations with scientific evidence.

THE PRIMARY OBJECTIVE

To perform a systematic review (SR) of the therapeutic management of primary VUR in pediatric urology.

MATERIAL AND METHODS

A systematic review has been performed, including scientific evidence-based medicine criteria, of the articles published in all of the available databases. Inclusion criteria concerning basic quality of the articles were considered essential, as well as exclusion criteria to be able to reject the articles.

RESULTS AND DISCUSSION

Subsequently, and following the critic reading of greater than 320 articles, statistical study of the grouped data was performed according to the type of treatment and to the benefits contributed by each treatment, and also to their undesirable effects. Finally we have made a comparison between our results and recent Cochrane Systematic Review. The following Conclusions were drawn from the results obtained and from the analysis of the texts. Both medical and surgical treatment present with similar effectiveness concerning resolution of grades I, II and III of VUR, and the former one is the recommended initial treatment following diagnosis. Endoscopic treatment is exactly as effective as open surgery for grades I, II and III with fewer undesirable effects secondary. There are no differences concerning the efficacy of the different injected substances. Not enough evidences exist for degrees IV and V that may recommend or advise against any of the treatments. In any degree of VUR, open surgical treatment is superior as far as medical treatment is concerned only regarding the number of acute pyelonephritis episodes during followup. This conclusion cannot be applied on endoscopic treatment.

Further investigation of confirmed urinary tract infection (UTI) in children under five years: a systematic review

BACKGROUND

Further investigation of confirmed UTI in children aims to prevent renal scarring and future complications.

METHODS

We conducted a systematic review to determine the most effective approach to the further investigation of confirmed urinary tract infection (UTI) in children under five years of age.

RESULTS

73 studies were included. Many studies had methodological limitations or were poorly reported. Effectiveness of further investigations: One study found that routine imaging did not lead to a reduction in recurrent UTIs or renal scarring. Diagnostic accuracy: The studies do not support the use of less invasive tests such as ultrasound as an alternative to renal scintigraphy, either to rule out infection of the upper urinary tract (LR- = 0.57, 95%CI: 0.47, 0.68) and thus to exclude patients from further investigation or to detect renal scarring (LR+ = 3.5, 95% CI: 2.5, 4.8). None of the tests investigated can accurately predict the development of renal scarring. The available evidence supports the consideration of contrast-enhanced ultrasound techniques for detecting vesico-ureteric reflux (VUR), as an alternative to micturating cystourethrography (MCUG) (LR+ = 14.1, 95% CI: 9.5, 20.8; LR- = 0.20, 95%CI: 0.13, 0.29); these techniques have the advantage of not requiring exposure to ionising radiation.

CONCLUSION

There is no evidence to support the clinical effectiveness of routine investigation of children with confirmed UTI. Primary research on the effectiveness, in terms of improved patient outcome, of testing at all stages in the investigation of confirmed urinary tract infection is urgently required.

Predictive risk factors for chronic renal failure in primary high-grade vesico-ureteric reflux

OBJECTIVE

To evaluate and define the risk factors predictive of chronic renal failure (CRF) in children with severe bilateral primary vesico-ureteric reflux (VUR), observed within the first year of life and with a long follow-up.

PATIENTS AND METHODS

The study comprised 50 patients presenting with grade 3-5 bilateral VUR diagnosed in the first year of life; 12 were suspected prenatally and confirmed shortly after birth, before any urinary tract infection (UTI). The mean (range) follow-up was 6.3 (1-16) years. The variables considered within the first year of life were: gender, prenatal diagnosis with no UTI, number of febrile UTIs, serum creatinine and urea nitrogen levels, metabolic acidosis, proteinuria, 24-h urine output, hypertension, bilateral renal length on ultrasonography and renal scarring on renal scintigraphy. CRF was defined as a creatinine clearance of <80 mL/min/1.73 m(2) at the last follow-up. The results were assessed using univariate and multivariate analyses (backward-stepwise multiple regression) of the selected variables.

RESULTS

CRF was detected at the last follow-up in 27 patients (54%), all boys, while renal function was normal in 23 (46%; seven girls). None of the 12 patients with prenatal diagnosis had UTI, but six had CRF. Febrile UTI was the presenting symptom in 38 (76%) patients and 17 (34%) of them had renal scarring. There was no significant difference between the prenatally detected VUR and febrile UTI group in the outcome as CRF. The univariate and multiple regression analysis showed that the first serum creatinine threshold of >6 mg/L before 1 year old was the most significant risk factor for CRF (P < 0.001; odds ratio 1.25).

CONCLUSIONS

Children with primary bilateral high-grade VUR and a serum creatinine of > 6 mg/L in the first year of life have a significant risk of developing CRF in the long-term. Prenatal diagnosis and postnatal febrile UTI do not modify the outcome for renal function.

Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features

Congenital anomalies of the lower urinary tract are a significant cause of morbidity in infancy. Radiologic investigation is an important source of clinical information in lower urinary tract disorders but should not inconvenience the patient, expose the patient to unnecessary radiation, or delay surgical correction. In pediatric patients with suspected underlying urologic structural anomalies, screening ultrasonography is commonly the initial diagnostic study. If dilatation of the urinary tract is confirmed, voiding cystourethrography is performed to determine the presence of vesicoureteral reflux (VUR) and other causes of upper tract dilatation. If VUR is confirmed, follow-up with nuclear cystography or echo-enhanced cystosonography may be performed. If VUR is excluded, nuclear diuresis renography is the primary test for differentiating between obstructed and nonobstructed megaureter. Intravenous urography can be used to specifically identify an area of obstruction and to determine the presence of duplex collecting systems and a ureterocele. Computed tomography and magnetic resonance (MR) imaging are unsuitable for general screening but provide superb anatomic detail and added diagnostic specificity. MR imaging is mandatory in the evaluation of associated spinal anomalies. MR urography can demonstrate ectopic extravesical ureteric insertions, thereby providing a global view of the malformation. Familiarity with anomalies of the lower urinary tract is essential for correct diagnosis and appropriate management.

[Role of direct radionuclide cystography and renal study by dimercaptosuccinic acid (DMSA) in the diagnosis and follow-up of vesicoureteral reflux]

AIM

To evaluate the role of isotopic studies in the diagnosis and follow-up of vesicoureteral reflux (VUR) and to present the results of our current protocol.

MATERIAL AND METHODS

Forty three patients with VUR were retrospectively studied with a mean follow-up of 43 years (1-11 years). VUR was diagnosed by voiding cystourethrography and followed-up by direct radionuclide cystography. During the follow-up all patients were studied by means of renal DMSA scintigraphy (21 were also studied during the acute phase of febrile urinary tract infection).

RESULTS

Eighty three renal units were examined. Voiding cystourethrography was positive for VUR in 49 renal units (59%; 8 grade I, 18 grade II, 15 grade III, and 8 grade IV). During the follow-up, direct radionuclide cystography showed decrease or disappearance of VUR in 29 renal units (35%; 4 grade I, 16 grade II, 7 grade III, and 2 grade IV). DMSA studies performed during the follow-up showed cortical lesions in 17 renal units (5 with VUR grade II, 7 with grade III, and 5 grade IV). Nine of 21 patients examined by DMSA during the acute phase of febrile urinary tract infection showed cortical damage (43%), and 6 of them (67%) progressed to cortical lesion in the follow-up DMSA.

CONCLUSIONS

The present protocol allows for the correct diagnosis and control of VUR, the early detection of acute renal damage, and the control of its evolution.

Vesicoureteral reflux: diagnosis and grading with echo-enhanced cystosonography versus voiding cystourethrography

PURPOSE

To evaluate the usefulness of echo-enhanced cystosonography compared with voiding cystourethrography (VCUG) for detecting and grading vesicoureteral reflux (VUR).

MATERIALS AND METHODS

Two hundred sixteen pediatric patients underwent cystosonography enhanced with SH U 508A, a galactose-based echo-enhancing agent. Sonograms of the kidneys and bladder were obtained before filling, during bladder filling, and during voiding. This examination was followed immediately with VCUG. Each kidney or portion of a kidney with its own complete collecting system was considered separately, for a total of 440 kidney units.

RESULTS

VUR was detected in 123 kidney units at cystosonography and in 104 at VCUG. In 401 kidney units, there was concordance between results at cystosonography and at VCUG regarding the presence or absence of VUR. Ninety-four kidney units showed VUR with both methods. Seventy-seven of the 94 refluxing units were depicted with the same grade of VUR with both modalities, and in 17 the VUR grade was greater at cystosonography than at VCUG. Twenty-nine of the 94 units showed VUR at only cystosonography, and 10 units at only VCUG. The McNemar test showed that cystosonography depicted a significantly (P = .003) higher number of units with VUR. By patient, VUR was depicted with both studies in 67 and with only one study in 25. VUR was seen at only cystosonography in 16 patients and at only VCUG in nine. The McNemar test for patients showed no significant difference between the two tests in detection of VUR.

CONCLUSION

Cystosonography with SH U 508A appears comparable to VCUG in the depiction of VUR.

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.

[Parenchymatous cicatrix and urinary tract infection: physiopathology and clinical implications]

Renal scarring is the main long term complication of acute pyelonephritis in children. The prevalence rate is hazardous since data from the literature are confusing with respect to reflux nephropathy, chronic pyelonephritis and renal hypoplasia. The pathology of such lesions consists in focal interstitial fibrosis. When the first pyelonephritic attack occurs during infancy, renal growth may be compromised. The current approach of renal scar assessment is based on dimercaptosuccinic acid (DMSA) scan. Bilateral extensive lesions may be responsible for altered glomerular filtration rate (GFR) and/or arterial hypertension. The management of overt scarring is conservative and careful prevention must be based on early and aggressive treatment of acute pyelonephritis.

Diagnosis of vesico-ureteric reflux

The demonstration and grading of reflux is crucial in examination and follow-up of any child with upper urinary tract infection. A variety of factors can influence the occurrence of reflux, e.g. race, genetics, state of maturation of the ureterovesical valve, diuresis, infection and bladder dysfunction, including obstruction and neurogenic disorders. Even when reflux is investigated under strictly standardized conditions, two consecutive bladder fillings frequently show different grades of reflux. Voiding cystourethrography is, to date, the only method with a generally accepted, well-defined grading of reflux. It also allows detection of intrarenal reflux and anatomical and functional information about the bladder and urethra that is unobtainable by other methods. It is therefore usually considered the method of choice. Radionuclide cystography and, possibly, contrast enhanced ultrasonography can be complementary to voiding cystourethrography, but mainly for postoperative follow-up and screening of siblings.

Imaging of renal scarring

Children with urinary tract infection should be investigated and followed up, as those with pyelonephritis may develop renal scarring. In this review, after discussing the advantages and disadvantages of various imaging modalities for diagnosis of renal scarring, it is concluded that DMSA scintigraphy and urography can both be used to detect significant renal scarring. With DMSA scintigraphy, small renal lesions (functional uptake defects) not seen at urography will also be detected. The long-term clinical significance of these lesions is, as yet, unknown. A normal DMSA scintigraphy after infection indicates low risk for clinically significant damage. In order to allow acute, reversible lesions to first disappear, a follow-up DMSA examination should not be performed until at least 6 mo after the acute infection. Ultrasonography in isolation cannot be recommended for the diagnosis 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.

Technical report: urinary tract infections in febrile infants and young children. The Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement

OVERVIEW

The Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement has analyzed alternative strategies for the diagnosis and management of urinary tract infection (UTI) in children. The target population is limited to children between 2 months and 2 years of age who are examined because of fever without an obvious cause. Diagnosis and management of UTI in this group are especially challenging for these three reasons: 1) the manifestation of UTI tends to be nonspecific, and cases may be missed easily; 2) clean voided midstream urine specimens rarely can be obtained, leaving only urine collection methods that are invasive (transurethral catheterization or bladder tap) or result in nonspecific test results (bag urine); and 3) a substantial number of infants with UTI also may have structural or functional abnormalities of the urinary tract that put them at risk for ongoing renal damage, hypertension, and end-stage renal disease (ESRD).

METHODS

To examine alternative management strategies for UTI in infants, a conceptual model of the steps in diagnosis and management of UTI was developed. The model was expanded into a decision tree. Probabilities for branch points in the decision tree were obtained by review of the literature on childhood UTI. Data were extracted on standardized forms. Cost data were obtained by literature review and from hospital billing data. The data were collated into evidence tables. Analysis of the decision tree was used to produce risk tables and incremental cost-effectiveness ratios for alternative strategies.

RESULTS

Based on the results of this analysis and, when necessary, consensus opinion, the Committee developed recommendations for the management of UTI in this population. This document provides the evidence the Subcommittee used in the development of its recommendations.

CONCLUSIONS

The Subcommittee agreed that the objective of the practice parameter would be to minimize the risk of chronic renal damage within reasonable economic constraints. Steps involved in achieving these objectives are: 1) identifying UTI; 2) short-term treatment of UTI; and 3) evaluation for urinary tract abnormalities.

The DMSA scan in paediatric urinary tract infection

The objective of the present paper was to review the use of the dimercaptosuccinic acid (DMSA) scan in urinary tract infection at British Columbia's Children's Hospital to determine the frequency of cortical defects and the association between vesico-ureteric reflux and the presence of cortical defects in children with urinary tract infection. A total of 129 consecutive children with a urinary tract infection referred for a DMSA scan in a 2-year period (January 1992-January 1994) were retrospectively studied. The results were analysed in terms of kidneys, and the incidence of cortical defects was determined. Eighty-eight patients (68%) had a radiographic micturating cysto-urethrogram within 6 months of the DMSA scan, and in this group the relationship of defects with vesico-ureteric reflux was determined. Overall, 81/258 (31%) of kidneys had a cortical defect on a DMSA scan. Of those who had a micturating cysto-urethrogram, 53/176 (30%) kidneys had vesico-ureteric reflux, and of those that had reflux, 21/53 (40%) had a cortical defect on a DMSA scan. In the group of children without reflux, 38/123 (31%) had a cortical defect. Renal cortical scan defects are common findings in paediatric urinary infection, and frequently occur in the absence of vesico-ureteric reflux. These defects represent either established scars or acute pyelonephritis that can proceed to scarring. The micturating cysto-urethrogram alone is insufficient as a screening modality to identify those kidneys at risk of renal scarring.

Trends in the health burden due to urinary tract infection in children in Australia

OBJECTIVE

To estimate the health burden of urinary tract infection in children less than 15 years of age in Australia and to ascertain whether any significant change has occurred during the past decade.

METHODOLOGY

The number of children less than 15 years of age who were admitted in New South Wales for urinary tract infection between 1981 and 1994 was ascertained from the Department of Health, and age and sex specific incidence rates were calculated using Australian Bureau of Statistics population data. Costs for inpatient care were calculated using the cost weights from Australia National Disease Related Groups Version 3 for urinary tract infection (DRG 577). The frequency of the four most commonly requested renal tract imaging procedures in children following urinary tract infection and which qualified for Medicare reimbursement were obtained from the Health Insurance Commission for 1984-1994: micturating cystourethrography, intravenous urography, renal ultrasonography, and nuclear medicine renal studies.

RESULTS

There were 1203 children who were admitted with urinary tract infection in New South Wales in 1994, at an estimated cost of $A1.6 million. Since 1981, the age standardized annual incidence of urinary tract infection requiring hospitalization has increased from 0.5 to 0.9 per 1000 children, largely because of an increase in the number of young children admitted (from 0.6 to 2.0 per 1000 children less than 5 years of age). In 1994, 46,230 non-inpatient renal imaging procedures were undertaken in children under 15 years of age at a cost of $A5.3 million.

CONCLUSIONS

Urinary tract infection is an important and increasing health problem for Australian children, particularly for preschool children. Whether this represents a true increase in the incidence of urinary tract infection or improved diagnosis and more intensive management is not possible to establish with this study design. Prospective population based studies are required to assess more completely the frequency with which urinary tract infection occurs in children and any changes that may be occurring.

Renal damage one year after first urinary tract infection: role of dimercaptosuccinic acid scintigraphy

OBJECTIVE

The aim of this study was to determine whether age, C-reactive protein (CRP), body temperature, or results of voiding cystourethrography at diagnosis of first-time symptomatic urinary tract infection could predict the risk of renal damage as evaluated by dimercaptosuccinic acid (DMSA) scintigraphy performed 1 year after the infection.

DESIGN

The study included 157 children (median age, 0.4 year, range, 5 days to 5.8 years) with first-time symptomatic urinary tract infection. In children 1 year of age or older, a body temperature of 38.5 degrees C or higher was necessary for inclusion. CRP and body temperature were measured at the time of infection, and voiding cystourethrography was performed shortly thereafter. DMSA scintigraphy was performed 1 year later in all children.

RESULTS

After 1 year, 59 (38%) of the 157 children had renal damage as evaluated by DMSA scintigraphy, and of these, 28 (47%) had reflux. There was a positive correlation between renal damage and CRP, body temperature, and reflux. Children with high levels of CRP, high fever, and dilating reflux had a risk of renal damage up to 10 times higher than children with normal or slightly elevated CRP levels, no or mild fever, and no reflux.

CONCLUSION

CRP concentration and body temperature at the index infection, in combination with the results of voiding cystourethrography, are useful in classifying children at high and low risk of scintigraphic renal damage 1 year after urinary tract infection.

High incidence of urinary tract infection in patients with coeliac disease

The concomitant occurrence of urinary tract infection (UTI) and coeliac disease was studied retrospectively among children with coeliac disease. There was a significantly higher risk of first time UTI in children with coeliac disease than in an unselected population of children. In the majority of cases UTI was associated with untreated, active coeliac disease.

Routine diagnostic imaging for childhood urinary tract infections: a systematic overview

OBJECTIVE

To assess the quality of the evidence on which current recommendations for routine diagnostic imaging for childhood urinary tract infection are based.

METHODS

A systematic overview of the literature using the MEDLINE database (1966 to October 1994), article bibliographies, and a manual search of current publications using Current Contents, was undertaken. Preset criteria were used to categorize study sample and design, and interrater reliability was assessed with a random sample.

RESULTS

A total of 434 publications were evaluated, and 63 studies met the criteria for inclusion. There was 100% interrater agreement on inclusion eligibility and design classification. No controlled trials or analytic studies evaluating routine diagnostic imaging were found. All 63 studies were descriptive, and only 10 were prospective. None of the studies provided evidence of the impact of routine imaging on the development of renal scars and clinical outcomes in children with their first urinary tract infection.

CONCLUSION

Methodologically sound, prospective studies are needed to assess whether children with their first urinary tract infection who have routine diagnostic imaging are better off than children who have imaging for specific indications. We conclude that the current recommendations are not based on firm evidence.

A prospective study of bacteriuria and pyuria in catheter specimens from hospitalized children, Durban, South Africa

In a prospective study of 180 children admitted consecutively to King Edward VIII Hospital, bacteriuria (BU) was detected in 47 (26%), associated with pyuria in 35. BU occurred in association with other common childhood diseases in all but one child: acute lower respiratory tract infection (LRTI) in 43%, gastro-enteritis (GE) in 34% and protein energy malnutrition (PEM) in 26%. Conversely, BU was detected in 24% of children with LRTI, 33% with GE and 38% with PEM. Children with or without BU thus presented with similar symptoms and signs, except for vomiting and dehydration which were more frequent in those with BU. The male:female ratio was higher in BU under 2 years of age. Localizing urinary tract symptoms and signs were infrequent. Only one of the 35 children in whom ultrasonography was performed showed structural defects. The organisms detected (mainly Escherichia coli) were resistant to commonly used antibacterial drugs. There was a high specificity for dipstix testing, but low sensitivity, possibly because of sampling by catheter. There were seven deaths, three with and four without BU. Other illnesses contributed to death in all cases. Our findings have implications for the management of children who are hospitalized for common diseases in developing countries. It is not clear whether pyuria and BU were transient or indicative of serious disease of the kidney and urinary tract.

The appropriateness of use and the clinical impact of micturating cystourethrography in paediatric practice

STUDY OBJECTIVE

To determine the appropriateness of use and the clinical impact of micturating cystourethrography (MCU) in paediatric practice.

DESIGN

Retrospective medical record review.

SETTING

A major teaching children's hospital in the Trent region.

PATIENTS

Consecutive sample of 120 children undergoing MCU during 1991-1992, identified from the radiology records.

MAIN OUTCOME MEASURES

The referring clinician's reasons for requesting an MCU; the clinical management plan pursued before and after the MCU, and the change in management initiated by the result of the examination; the appropriateness of use of the test, as determined by the presence or absence of a valid indication for MCU in the specific clinical situation.

RESULTS

The change in patient management attributable to the MCU result could be categorized as: no change (19%); decision to end the imaging investigation of the patient (33%); decision to end all investigations, and prophylactic or therapeutic interventions (16%); decision to discontinue chemoprophylaxis (2%); decision to end the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (6%); decision to continue the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (13%); and decision to operate or help in planning the surgical treatment required (11%). Inappropriate use of the test was observed in 20% of the cases.

CONCLUSIONS

This study provides a basis for understanding the use of MCU in paediatric practice. The findings that 19% of the cystourethrograms had no appreciable effect, and that 20% of the examinations were used inappropriately show the need for increased effort to minimize overuse of the test.

Diagnostic significance of 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy in urinary tract infection

A total of 106 children with symptomatic urinary tract infection (73 girls and 33 boys, 0-15.9 years of age) were studied by means of a dimercaptosuccinic acid (DMSA) scan, renal ultrasound, and a desmopressin test during infection and at follow up approximately two months later. At follow up they were also investigated by means of intravenous urography (IVU) and micturition cystourethrography (MCU). During infection 23 children had a normal DMSA scan while 83 children had an abnormal one. The median C reactive protein and SD score for renal concentration capacity in the former group were 15 (range < 10-178) mg/l and -1.0 SD score (range -2.4 to 1.8), respectively, and in the latter group 98 (range < 10-320) mg/l and -3.1 SD score (range -5.7 to 1.1), respectively. In the former group there was no significant finding in any child on ultrasound or IVU and only one had significant vesicoureteric reflux (VUR) (grade 3). At follow up 51 children had a normal DMSA scan while 55 children showed persistent changes. The median SD score for renal concentration capacity in the former group was -0.9 SD score (range -3.2 to 1.4) and in the latter group -1.6 SD score (range -4.6 to 2.5). No significant changes were found in the former group on ultrasound or IVU and only two children had significant VUR (grade 3). In the latter group 20 children showed changes on ultrasound, 15 showed changes on IVU, and 23 had VUR. These results suggest that a normal DMSA scan during or approximately two months after urinary tract infection in children indicates a low risk of finding significant pathology of the urinary tract.

99mTechnetium-dimercaptosuccinic acid scan in the diagnosis of acute pyelonephritis in children: relation to clinical and radiological findings

Seventy-two children, 59 girls and 13 boys, 0.1-15.9 (median 1.1) years of age, with acute pyelonephritis (APN) were investigated with the aid of a dimercaptosuccinic acid (DMSA) scan, renal ultrasonography (US) and a desmopressin test within 5 days of admission. Sixty-two children were reinvestigated approximately 2 months later when intravenous urography (IVU) and micturition cysto-urethrography were also performed. During infection, 92% of the children showed changes in the DMSA scan with 69% by US, and the two investigations agreed in 58% of the kidneys. At follow-up, 68% showed changes in the DMSA scan, 47% by US and 48% by IVU. The DMSA scan and IVU agreed in 60% of the kidneys. Twenty-nine percent of the children had vesico-ureteric reflux (VUR). The presence of grade greater than or equal to 3 VUR was associated with greater defects on the DMSA scan during infection, and at follow-up with a higher frequency of persistent changes compared with no VUR (P less than 0.02 and 0.01, respectively). During infection the size of the defect on the DMSA scan correlated with renal volume and C-reactive protein and inversely with the glomerular filtration rate, and at follow-up it correlated inversely with the renal concentration capacity. The DMSA scan is a sensitive method for diagnosing and localizing APN in children, and findings on DMSA scan show a weak but significant correlation with routine clinical and radiological parameters. It is suggested that persistent renal damage after APN in children without VUR may be more common than previously assumed.