Kidney Ultrasonography After First Febrile Urinary Tract Infection in Children: A Systematic Review and Meta-analysis

Prediction model for severe vesicoureteral reflux in children with urinary tract infection and/or hydronephrosis

BACKGROUND

As voiding cystourethrography is invasive and exposes to radiation and urinary tract infection (UTI), identifying only high-grade reflux is important. We aimed to identify clinical, laboratory and imaging variables associated with high-grade primary reflux in children presenting with UTIs and/or urinary tract dilatation and develop a prediction model for severe reflux.

METHODS

Data of children who underwent voiding cystourethrography due to UTI and/or urinary tract dilatation were retrospectively analyzed for demographic, clinical and imaging findings. Patients with severe (grades 4-5) reflux were compared with the rest for these parameters and a prediction model was developed for severe reflux.

RESULTS

The study included 1044 patients (574 female). Severe reflux was present in 86 (8.2%) patients. Age < 2 years, male sex, non-E. coli uropathogens, UTD-P3 dilatation and multiple kidney scars on DMSA scintigraphy were associated with severe reflux. Using these variables a prediction model for severe reflux with a score ranging from 0-7 and accuracy rate of 93.4% was developed. A score ≥ 5 had sensitivity 44.2%, specificity 97.4%, PPV 60.3%, NPV 95.1% and OR 29.5 for severe reflux. Scores ≥ 5 and ≥ 4 catch 44% and 73% of severe reflux, while prevent invasive voiding cystourethrography in 94.0% and 83.6% of patients, respectively.

CONCLUSION

Age < 2 years, male sex, non-E. coli uropathogen growth, presence of UTD-P3 dilatation on ultrasonography and multiple scars on DMSA scintigraphy are risk factors for severe reflux. A scoring system based on these variables appears to be effective in predicting the presence of severe reflux and eliminating unnecessary voiding cystourethrography.

Recent Developments in Pediatric Nephrology

Urinary tract infection (UTI) is a common bacterial infection in children that affects 1 [...].

Reduced kidney size and renal function of high-grade vesicoureteral reflux and intrarenal reflux in contrast-enhanced voiding urosonography

BACKGROUND

Vesicoureteral reflux (VUR) is a common pediatric urological condition associated with renal scarring, hypertension, and chronic kidney disease. Contrast-enhanced voiding urosonography (ceVUS) has emerged as a promising technique for diagnosing and evaluating VUR, with intrarenal reflux (IRR) often detected using this method. This study aimed to explore the relationship between different VUR grades and IRR on ceVUS, and assess the impact of VUR and IRR on kidney size and function.

METHODS

We reviewed all ceVUS studies from January 2019 to December 2023 conducted at West China Hospital, Sichuan University. Both video clips and digital images of the ceVUS examinations were recorded. A total of 220 uretero-renal units (URUs) of 110 children (67 males and 43 females) were included in this study.

RESULTS

Among the 220 URUs assessed, 134 were diagnosed with VUR, and 25 exhibited IRR, with IRR exclusively observed in patients with grade II VUR or higher. Upon age and sex matching, the severity of IRR showed a significant positive correlation with high-grade VUR (P < 0.001). Notably, patients with high-grade VUR and IRR displayed reduced kidney size compared to those without VUR or IRR (P < 0.05). Furthermore, patients with high-grade VUR and IRR had reduced DMSA renal function (P = 0.015, P = 0.012, respectively), and patients with high-grade VUR had more DMSA scars (P = 0.027), compared with those without VUR or IRR.

CONCLUSION

Our study highlights that on ceVUS, the IRR degree was associated with the high-grade VUR, along with reductions in kidney size and renal function in patients with high-grade VUR and IRR.

Clinical characteristics and nomogram model for predicting the risk of recurrence of complicated urinary tract infection in pediatric patients

Complicated urinary tract infection (cUTI) has higher incidences of antibiotic resistance, recurrence, chronicity, and progression. There exist differences in the immune functions, anatomical structures and physiological functions of urinary tract system between children and adults. In addition, the immature stage of hygiene habit development and the inability to express discomfort accurately all contribute to cUTI recurrence in pediatric patients. cUTI recurrence in children can lead to serious consequences such as growth and development delay, renal scars, and progression to end-stage kidney diseases. Despite the high incidence of cUTI recurrence, no predictive model currently exists to guide targeted intervention in pediatric patients. This study aimed to establish a nomogram to predict the risk of cUTI recurrence in children, thereby facilitating targeted prevention and treatment strategies in pediatric patients. The nomogram was developed based on a retrospective cohort that included 421 pediatric patients with cUTI at West China Second University Hospital from January 2020 to August 2023. The patients were randomly divided into a training set and a validation set in a 3:1 ratio. Logistic regression analysis was used to identify risk factors and construct the nomogram for predicting the risk of cUTI recurrence, followed by validation and performance analysis. Of the 421 children with cUTI, the recurrence rate of cUTI was 68.4% (288 cases) during an average follow-up duration of 22.9 months. The nomogram comprised female gender, history of urinary tract surgery, Escherichia coli in urine culture, renal dysfunction, and vesicoureteral reflux as predictors of cUTI recurrence in pediatric patients. The model showed favorable performance with C-index values of 0.735 and 0.750 in the training dataset and the validation dataset, respectively. The decision curve analysis revealed that the nomogram might be clinically useful. The reliable nomogram would be beneficial for clinicians to identify children with high risks of cUTI recurrence for targeted intervention.

Predictors of Abnormal Renal Ultrasonography in Children With Urinary Tract Infection

BACKGROUND AND OBJECTIVES

The 2011 American Academy of Pediatrics guidelines recommended a renal and bladder ultrasound (RBUS) after the first febrile urinary tract infection (UTI) in infants. Abnormal RBUS findings may be due to inflammation from the acute UTI or from vesicoureteral reflux (VUR), which may require a voiding cystourethrogram (VCUG) to diagnose, increasing health care costs. Our objective was to evaluate the effect of timing of imaging relative to the acute illness on abnormal dilation on RBUS and VCUG findings.

METHODS

Multicenter, retrospective study of patients aged 2 to 24 months presenting with first UTI and RBUS from January 1, 2015, to December 31, 2019. Demographics, isolated pathogen, and timing of RBUS and VCUG relative to urine culture date were recorded and compared.

RESULTS

A total of 227 patients were included. On multivariable logistic regression, increased time in days to RBUS was associated with decreased odds of abnormal dilation (adjusted odds ratio, 0.980; P = .018) in those patients meeting culture criteria for UTI (for each additional day of delay in obtaining RBUS, the adjusted odds of detecting dilation decreased by ∼2%). There was no significant association between timing of imaging and VUR on VCUG. Additionally, 32% of patients underwent RBUS who did not meet UTI culture criteria but had similar rates of abnormal dilation and VUR to those meeting UTI culture criteria.

CONCLUSIONS

Increased time to RBUS led to decreased odds of abnormal dilation, suggesting that delaying RBUS may lead to fewer false-positive results, which may limit unnecessary additional testing and reduce health care costs. Additionally, a significant number of patients who did not meet UTI culture criteria underwent RBUS but had similar results to those meeting criteria, suggesting that the previous colony-forming unit definition for UTI may be suboptimal.

NUM-score: A clinical-analytical model for personalised imaging after urinary tract infections

AIM

To identify predictive variables and construct a predictive model along with a decision algorithm to identify nephrourological malformations (NUM) in children with febrile urinary tract infections (fUTI), enhancing the efficiency of imaging diagnostics.

METHODS

We performed a retrospective study of patients aged <16 years with fUTI at the Emergency Department with subsequent microbiological confirmation between 2014 and 2020. The follow-up period was at least 2 years. Patients were categorised into two groups: 'NUM' with previously known nephrourological anomalies or those diagnosed during the follow-up and 'Non-NUM' group.

RESULTS

Out of 836 eligible patients, 26.8% had underlying NUMs. The study identified six key risk factors: recurrent UTIs, non-Escherichia coli infection, moderate acute kidney injury, procalcitonin levels >2 μg/L, age <3 months at the first UTI and fUTIs beyond 24 months. These risk factors were used to develop a predictive model with an 80.7% accuracy rate and elaborate a NUM-score classifying patients into low, moderate and high-risk groups, with a 10%, 35% and 93% prevalence of NUM. We propose an algorithm for approaching imaging tests following a fUTI.

CONCLUSION

Our predictive score may help physicians decide about imaging tests. However, prospective validation of the model will be necessary before its application in daily clinical practice.

Review of Urinary Tract Infections and Pyelonephritis

Urinary tract infections (UTIs) are serious bacterial infections affecting children of all ages. An understanding of the methods of urine collection is important to prevent the contamination of urine specimens and to interpret results. The diagnosis of a UTI requires appropriate interpretation of both urinalysis and urine culture results because testing must indicate evidence of inflammation and the presence of bacteria. Rapid treatment of UTIs is imperative to prevent acute decompensation and systemic illness. Empiric antibiotics should be narrowed as soon as possible to tailor antibiotic treatment and limit antibiotic overuse. Imaging with a renal ultrasound scan is recommended for all infants with first febrile UTIs rather than a voiding cystourethrogram. An additional goal of UTI treatment is to prevent renal scarring, which can lead to lifelong health consequences. Children with anatomic abnormalities of the urinary tract and those who have recurrent UTIs are at increased risk of renal scarring. [Pediatr Ann. 2024;53(6):e217-e222.].