Risk assessment of renal cortical scarring with urinary tract infection by clinical features and ultrasonography

AIMS—To address some of the issues in the ongoing debate over the optimal diagnostic imaging following childhood urinary tract infection (UTI), by determining the risk of missing renal cortical scarring which would be detected on a technetium-99m dimercaptosuccinic acid (DMSA) gold standard if ultrasound alone were used, factoring for clinical features (upper or lower tract), UTI recurrence, and age group (infants, preschool, or school age).
METHODS—Details of UTI clinical features and recurrence were recorded for 990 children with a proven UTI, and their DMSA and ultrasound results were compared for each kidney.
RESULTS—The risks of missing DMSA scarring varied between 0.4% (school age children with solitary lower tract UTI) and 11.1% (infants with recurrent upper tract UTI).
CONCLUSIONS—UTI clinical features are important in assessing the need for DMSA imaging. Current UK imaging guidelines are endorsed, although preschool children with solitary lower tract UTI remain a controversial group and more attention needs to focused on children with recurrent UTI.

     

Primary and acquired renal scarring in boys and girls with urinary tract infection

OBJECTIVES: To determine when pyelonephritic renal scarring was detected in children with urinary tract infection (UTI) and characterize those with primary and acquired scarring, respectively. STUDY DESIGN: A population-based cohort of 1221 children (989 girls and 232 boys) with first recognized symptomatic UTI, aged 0 to 15 years, were diagnosed and followed up prospectively at a single children's hospital; 652 had febrile UTI. Seven hundred fifty-three were evaluated by urography. Renal scarring was classified as primary or acquired, the latter without signs of scarring at the first investigation. To evaluate the frequency of recurrent UTI in those with acquired scarring, a comparison with group-matched children without scarring was performed. RESULTS: A total of 74 children without obstruction had renal scarring (acquired in 40). Primary scarring was found in 18 of 21 (86%) of the boys and 16 of 53 (30%) of the girls (P <.001). The majority of boys with scarring had dilated reflux (67%) in contrast to girls (23%). Recurrent UTI was rare in boys, whereas girls with acquired scarring had significantly more febrile recurrences than girls without scarring. CONCLUSIONS: Most boys had primary, probably congenital, reflux-associated renal damage, whereas most girls had acquired scarring related to recurrences of febrile UTI.     

Lipid-A-antibodies--indicators for the risk of renal scarring in children with urinary tract infection

The levels of IgG- and IgM-antibodies against lipid A were determined by an ultramicro-ELISA in 54 children between 2 months and 13 years of age with non-obstructive urinary tract infections at the onset of the infection and subsequently after 3, 6 and 12 months. Children older than 2 years who later developed renal scarring as shown by intravenous pyelograms had higher levels of IgG antibodies than those without scars. This correlation was not found in children younger than 2 years of age. IgM-antibody levels did not correlate with the risk of scar formation. We conclude that the IgG-antibody level against lipid A is a useful indicator for early recognition of children over the age of two years who will later develop renal scars. The ultramicro-ELISA technique makes screening for children at risk possible at a low cost.     

Elevated serum procalcitonin values correlate with renal scarring in children with urinary tract infection

BACKGROUND: Urinary tract infection (UTI) in young children carries the risk of parenchymal damage and sequelae. The location of the infection within the urinary tract influences decisions regarding both therapeutics and follow-up. Because clinical features and laboratory markers of infection at an early age are not specific, it is difficult to make a distinction between lower UTI and acute pyelonephritis. Procalcitonin (PCT) has been studied as a marker of severe bacterial infection. The aim of this study was to test the usefulness of PCT concentration in serum to distinguish between uncomplicated UTI and severe acute pyelonephritis with renal scars. METHODS: PCT was measured by immunoluminometric assay in serum samples from children with microbiologically documented infection. Severe renal involvement was assessed by 99mTc-dimercaptosuccinic acid gammagraphy done 5 to 6 months after the episode to check for the presence of parenchymal scars. C-reactive protein (CRP) and leukocyte count were also measured. RESULTS: PCT at presentation showed a significant correlation (P < 0.001) with the presence of renal scars in children with UTI. Using a cutoff of 1 ng/ml for PCT and 20 mg/l for CRP, sensitivity and specificity in distinguishing between urinary tract infection with and without renal damage were 92.3 and 61.9%, respectively, for PCT and 92.3 and 34.4% for CRP. Positive and negative predictive values were 32 and 97.5%, respectively, for PCT and 23 and 95%, respectively, for CRP. CONCLUSIONS: A low PCT value at admission indicates a low risk of long term renal scarring. Increased PCT values at admission correlate with the presence of scars. PCT values have proved to be more specific than CRP and leukocyte count for identifying patients who might develop renal damage.     

Bilirubin levels predict renal cortical changes in jaundiced neonates with urinary tract infection

Background  This study was undertaken to determine the incidence of urinary tract infection (UTI) and the frequency of anatomical abnormalities in newborns with unexplained jaundice and to find out if there is any correlation between bilirubin level and renal damage. Methods  We studied 462 full-term neonates for UTI. They were aged 3–25 days, with either high (>10 mg/dL) or prolonged (>10 days) hyperbilirubinemia, with or without manifestations such as fever, vomiting, diarrhea, poor feeding, lethargy, and irritability. Neonates positive for UTI were further investigated with ultrasound, cystourethrography, and acute phase renal scintigraphy with technetium-99m dimercaptosuccinate acid (DMSA). Results  Thirty neonates (6.5%) were found to have UTI. Twenty-eight of them had indirect hyperbilirubinemia and two had direct hyperbilirubinemia, with total bilirubin levels of 11.8–20.1 mg/dL. None of the neonates was found to have jaundice because of other reasons such as infection. Vesicoureteral reflux was found in 5 neonates and one of them was combined with hydronephrosis. Renal scintigraphy with technetium-99m DMSA showed renal cortex changes in 14 (46.7%) of the 30 neonates with UTI. These 14 neonates also had increased levels of bilirubin in comparison to those with normal findings of DMSA. Conclusions  The incidence of UTI in uncomplicated neonatal jaundice is relatively high. Anatomical abnormalities of the urinary tract are not rare in infected children. Increased bilirubin levels are related to pathological findings in renal scintigraphy.     

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.     

Frequency and clinical features of urinary tract infection in paediatric out-patients in Nigeria

A survey of urinary tract infections (UTI) was conducted in a paediatric out-patient department in Northern Nigeria over six months. The most common presenting complaints of UTI were pyrexia of unknown origin (PUO) and mild diarrhoea. The frequency of symptomatic UTI in out-patients was estimated at 0.4%. Asymptomatic UTI was common in children with nephrotic syndrome (16%) and severe malnutrition (23%). Abnormalities of the urinary tract were found on I.V.P. in four out of twelve boys and one out of nine girls with symptomatic infection. Micturating cystograms (MCUG) were of less value because even if severe ureteric reflux was found, long term follow-up was not practical. Follow-up could be maintained with greater success from local clinics.     

Febrile urinary tract infection, vesicoureteral reflux, and renal scarring: current controversies in approach to evaluation

The ideal approach to the radiological evaluation of children with urinary tract infection (UTI) is in a state of confusion. The conventional bottom-up approach, with its focus on the detection of upper and lower urinary tract abnormalities, including vesicoureteral reflux, has been challenged by the top-down approach, which focuses on confirming the diagnosis of acute pyelonephritis before more invasive imaging is considered. Controversies abound regarding which approach may best assess the ultimate risk for reflux-related renal scarring. Evolving practices motivated by the emerging evidence, the desire to minimize unnecessary interventions, as well as improve compliance with recommended testing, have added to the current controversies. Recent guideline updates and ongoing clinical trials hopefully will help in addressing some of these concerns.     

The presence of vesicoureteric reflux does not identify a population at risk for renal scarring following a first urinary tract infection.

BACKGROUND: Childhood urinary tract infection (UTI) with or without vesicoureteric reflux (VUR) may predispose to renal scarring. There is no clear consensus in the literature regarding imaging following UTI in infancy. AIMS: To define the role of cystography following a first UTI in children aged under 1 year, when urinary tract ultrasonography (US) is normal. METHODS: Retrospective data collection of 108 children (216 renal units) aged under 1 year at the time of a bacteriologically proven UTI. All had a normal US and underwent both catheter cystogram and DMSA test. Sensitivity, specificity, likelihood ratios positive and negative, and diagnostic odds ratio were calculated for VUR on cystography versus scarring on DMSA. RESULTS: VUR was shown in 25 (11.6%) renal units. Scarring on DMSA was seen in 8 (3.7 %) kidneys. Only 16% of kidneys with VUR had associated scarring; 50% of scarred kidneys were not associated with VUR. The likelihood ratio positive was 4.95 (95% CI 2.22 to 11.05) and the likelihood ratio negative was 0.56 (95% CI 0.28 to 1.11). The diagnostic odds ratio was 8.9, suggesting that cystography provided little additional information. CONCLUSION: Since only 16% of children with VUR had an abnormal kidney, the presence of VUR does not identify a susceptible population with an abnormal kidney on DMSA. In the context of a normal ultrasound examination, cystography contributes little to the management of children under the age of 1 year with a UTI. In this context, a normal DMSA study reinforces the redundancy of cystography.     

Risk of urinary tract infection in infants and children with acute bronchiolitis

OBJECTIVES:

To estimate the prevalence of urinary tract infection in infants and children with bronchiolitis.

METHODS:

A retrospective cross-sectional study involving patients zero to 24 months of age who were hospitalized with acute bronchiolitis was conducted.

RESULTS:

A total of 835 paediatric patients with acute bronchiolitis were admitted to the paediatric ward between January 2010 and December 2012. The mean (± SD) age at diagnosis was 3.47±2.99 months. There were 325 (39%) girls and 510 (61%) boys. For the purpose of data analysis, the patient population was divided into three groups: group 1 included children hospitalized with respiratory syncytial virus (RSV) bronchiolitis; group 2 included children hospitalized with clinical bronchiolitis with no virus detected; and group 3 included children hospitalized with clinical bronchiolitis due to a respiratory virus other than RSV. Results revealed that urinary tract infection was present in 10% of patients, and was most common in group 3 (13.4%) followed by group 2 (9.7%), and was least common in group 1 (6%) (P=0.030).

CONCLUSIONS:

The possibility of a urinary tract infection should be considered in a febrile child with a diagnosis of bronchiolitis, particularly if the trigger is a respiratory virus other than RSV.     

The role of DMSA scans in evaluation of the correlation between urinary tract infection, vesicoureteric reflux, and renal scarring

The correlation between urinary tract infection (UTI), vesicoureteric reflux (VUR) and renal scarring was studied in 89 patients (177 renal units; 1 solitary kidney) during the period 1997–2000. There were 63 males and 26 females; ages ranged from neonates to 14 years. UTI was diagnosed on the basis of a positive urine culture, VUR was diagnosed and graded by micturating cystourethrogram (MCU), and renal scarring was assessed by technetium 99 m Tc-dimercaptosuccinic acid (DMSA) scan. Ultrasonography (US) was done to evaluate renal tract dilatation and other structural abnormalities. A follow up DMSA scan was performed approximately 6 months after the initial scan. VUR was present in 106 of the 171 renal units in which it was studied and absent in 65 units. The majority of the VUR was grade V. Renal scars were seen in 90 of 177 renal units at presentation and in 72 of the 163 renal units studied at follow-up. Some information was lacking in 31 patients; hence, the correlation between UTI, VUR, and renal scarring was done in 58 patients. The majority of the suspected scars at presentation were not seen at follow-up, but most of the established scars persisted. Only 2 renal units showed scars for the first time on follow-up. On US, approximately 50% of normal kidneys showed either suspicious or established scars on DMSA scan, and patients with bilateral abnormality on US showed renal scars. Renal scars were seen in 15 of 23 children without VUR, 17 of 18 with unilateral VUR, and 16 of 17 with bilateral VUR. Thus, there is a cause-and-effect relationship between UTI and renal scarring that is made worse by VUR. DMSA scans have been shown to be the most reliable method of assessing renal scarring, and an abnormal US scan showing upper-tract dilatation or a structural abnormality may have a predictive value in the detection of renal scarring. Accepted: 18 April 2001     

Management of fetal urinary tract anomalies detected by prenatal ultrasonography.

Over a three and a half year period 32 babies were referred with a urinary tract anomaly diagnosed by prenatal ultrasound. This diagnosis was subsequently confirmed in 19 infants by postnatal assessment. Three of 13 infants in whom the original diagnosis was incorrect were subsequently found to have intra-abdominal pathology but no urological anomaly, while the other 10 had lesions in the urinary tract but not those suggested prenatally. Nineteen of the 29 babies with urological abnormalities were clinically normal at birth; 20 underwent surgery. There were three deaths; two from a combination of renal and pulmonary failure secondary to posterior urethral valves, and a third (in an infant who had normal renal function) from diaphragmatic hernia and cardiac anomalies. Prenatal diagnosis was thought to have been of benefit in six patients, of probable benefit in 16, and of no benefit in seven.     

Breast-feeding and urinary tract infection.

A case-control study was conducted to study the association between breast-feeding and urinary tract infection. Case patients were 128 infants aged birth to 6 months with urinary tract infection. Control infants were 128 infants admitted to the same ward with an acute illness. The results support the hypothesis that breast-feeding protects infants against urinary tract infection.     

Imaging the urinary tract in children with urinary tract infection

Aim: To evaluate whether ultrasonography (US) alone is sufficient in imaging the urinary tract in 1185 children with urinary tract infection (UTI). Methods: The reports on US and voiding cystourethrography (VCUG) were reviewed. Results: Initial US was normal in 861/1185 patients (73%). VCUG revealed abnormal findings in 285/861 (33%), of which grade III–V vesicoureteral reflux (VUR) comprised 97 cases (11%). During follow‐up, VUR had resolved in 88/97 (91%) patients: in 50/57 (88%) patients without active treatment for VUR, in 27/29 (93%) with endoscopic and in 11/11 (100%) with open surgery for VUR. During follow‐up, 11/97 patients (11%) had developed new renal scarring detectable in US, but no renal impairment occurred. Except for VUR, VCUG showed nonobstructive urethral valves in two infant boys with normal initial US. Thus, in 861 children with normal initial US, 40 patients with grade III–V VUR and two patients with significant nonreflux pathology may have benefited from surgical treatment, giving the total number of possibly missed pathological finding in 42/861 (4.9%) cases if VCUG had not been performed. Conclusion: We suggest that children with UTI could be examined using US alone and to use VCUG only after additional indications.