Postnatal imaging of prenatally detected hydronephrosis-when is voiding cystourethrogram necessary?

Update on imaging recommendations in paediatric uroradiology: the European Society of Paediatric Radiology workgroup session on voiding cystourethrography

Voiding cystourethrography (VCUG) is a fluoroscopic technique that allows the assessment of the urinary tract, including the urethra, bladder, and-if vesicoureteral reflux (VUR) is present-the ureters and the pelvicalyceal systems. The technique also allows for the assessment of bladder filling and emptying, providing information on anatomical and functional aspects. VCUG is, together with contrast-enhanced voiding urosonography (VUS), still the gold standard test to diagnose VUR and it is one of the most performed fluoroscopic examinations in pediatric radiology departments. VCUG is also considered a follow-up examination after urinary tract surgery, and one of the most sensitive techniques for studying anatomy of the lower genitourinary tract in suspected anatomical malformations. The international reflux study in 1985 published the first reflux-protocol and graded VUR into five classes; over the following years, other papers have been published on this topic. In 2008, the European Society of Paediatric Radiology (ESPR) Uroradiology Task Force published the first proposed VCUG Guidelines with internal scientific society agreement. The purpose of our work is to create a detailed overview of VCUG indications, procedural recommendations, and to provide a structured final report, with the aim of updating the 2008 VCUG paper proposed by the European Society of Paediatric Radiology (ESPR). We have also compared VCUG with contrast-enhanced VUS as an emergent alternative. As a result of this work, the ESPR Urogenital Task Force strongly recommends the use of contrast-enhanced VUS as a non-radiating imaging technique whenever indicated and possible.

Stratifying Antenatal Hydronephrosis: Predicting High-Grade VUR Using Ultrasound and Scintigraphy

(1) Background: Antenatal hydronephrosis (AHN), detected in approximately one percent of prenatal ultrasounds, is caused by vesicoureteral reflux (VUR) in 15-21% of cases, a condition with significant risks such as urinary tract infections and renal scarring. Our study addresses the diagnostic challenges of VUR in AHN. Utilizing renal ultrasonography and scintigraphy, we developed a novel scoring system that accurately predicts high-grade VUR, optimizing diagnostic precision while minimizing the need for more invasive methods like voiding cystourethrogram (VCUG); (2) Methods: This retrospective study re-analyzed renal ultrasonography, scintigraphy, and VCUG images from infants admitted between 2003 and 2013, excluding cases with complex urinary anomalies; (3) Results: Our analysis included 124 patients (75% male), of whom 11% had high-grade VUR. The multivariate analysis identified visible ureter, reduced renal length, and decreased differential renal function (DRF) as primary predictors. Consequently, we established a three-tier risk score, classifying patients into low, intermediate, and high-risk groups for high-grade VUR, with corresponding prevalences of 2.3%, 22.2%, and 75.0%. The scoring system demonstrated 86% sensitivity and 79% specificity; (4) Conclusions: Our scoring system, focusing on objective parameters of the visible ureter, renal length, and DRF, effectively identifies high-grade VUR in AHN patients. This method enhances diagnostics in ANH by reducing reliance on VCUG and facilitating more tailored and less invasive patient care.

Voiding Cystourethrogram Before Pyeloplasty: To Do or Not To Do?

OBJECTIVE

To assess the incidence of concomitant vesicoureteral reflux (VUR) in unilateral cases of ureteropelvic junction obstruction (UPJO) and to identify factors that predict VUR.

METHODS

Files of 381 pediatric patients who underwent unilateral pyeloplasty between 2000 and 2017 were retrospectively reviewed. A total of 270 patients with available data and ≥5 years of follow-up were eligible for this study. Demographic parameters, preoperative hydronephrosis grade, renal pelvis anteroposterior diameter (APD), renal parenchymal thickness (PT), split renal functions on MAG-3 scan and VUR status were noted. The patients were divided into two groups: those with concomitant VUR (group I, n: 24, 8.9%) and those without VUR (group II, n: 246, 91.1%).

RESULTS

Among 270 patients (205 boys, 75.9%) with a median age of 4 months (2-98), 197 (72.9%) had antenatal hydronephrosis. Median follow-up was 11 years (5-22). Among 24 patients with concurrent VUR, 6 (25%) had grade II VUR, whereas grade III-V VUR was detected in 18 (75%). Of these, 12 (50%) had ipsilateral VUR, 3 (12.5%) had contralateral, and 9 (37.5%) had bilateral VUR. In a median 137-month follow-up, spontaneous VUR resolution was observed in 6 (25%) patients, whereas 15 (62.5%) patients underwent endoscopic subureteral injection and 3 (12.5%) patients ureteroneocystostomy, respectively. Preoperative APD [35.5, (Inter Quantile Range) IQR (27.6-36.0) vs 26.5 IQR (25.0-35.0), P = .004] were significantly higher in group I, whereas group I had significantly lower PT [3.7, IQR (3.4-6.4) vs 5.8 IQR (4.4-6.1), P = .026]. Predictive factors for concomitant VUR were presentation with febrile UTI (odds ratio (OR): 2.769, P = .048), PT <3.95 mm (OR: 1.367, P = .043), and APD >28.8 mm (OR: 1.035, P = .001).

CONCLUSION

Our results indicated that concomitant VUR and UPJO might be detected in 1 out of every 11 patients undergoing pyeloplasty, while some type of surgical intervention for VUR was required in 75% of these patients. Thus, voiding cystourethrogram prior to pyeloplasty may be limited in those presenting with febrile urinary tract infection, having higher APD and lower PT on preoperative urinary ultrasonography.

Antibiotic prophylaxis for prevention of urinary tract infections in the first year of life in children with vesicoureteral reflux diagnosed in the workup of antenatal hydronephrosis: a systematic review

BACKGROUND

Children with antenatal hydronephrosis (ANH) diagnosed with postnatal asymptomatic vesicoureteral reflux (VUR) are thought to be at higher risk of urinary tract infection (UTI). As such, continuous antibiotic prophylaxis (CAP) is empirically recommended until age of toilet training; however, there are limited data to support this. The objective of this systematic review was to summarize the existing data and compare UTI rates in infants with asymptomatic VUR on CAP during the first year of life, to those not on CAP. Secondary objectives were to determine associated risk factors with UTI development.

METHODS

A systematic search of all relevant studies and abstracts was conducted using 4 electronic databases by utilizing appropriate key words by an expert hospital librarian. Eligible studies included children with prenatal hydronephrosis, asymptomatic VUR with or without CAP, and reported on development of UTI in the first year.

RESULTS

Of 6903 citations screened, 18 were selected, giving a total population of 829 (69.4% male, median age 57 days) who met the inclusion criteria. Most studies were retrospective and of low-quality evidence. Overall, 15.4% of patients developed at least one breakthrough UTI and females had a higher risk of UTI (odds ratio (OR) 2.3, 95% CI 1.1-4.7). Comparison with children not taking CAP was not readily reported, and meta-analysis could not be completed.

CONCLUSIONS

Randomized controlled trials and standardized reporting of clinical variables are required to understand the protective effect of antibiotic prophylaxis in this cohort.

A clinical predictive model of renal injury in children with isolated antenatal hydronephrosis

Background

Antenatal hydronephrosis (ANH) affects ∼1-5% of pregnancies. The aim of this study was to develop a clinical prediction model of renal injury in a large cohort of infants with isolated ANH.

Methods

This is a longitudinal cohort study of 447 infants with ANH admitted since birth between 1989 and 2015 at a tertiary care center. The primary endpoint was time until the occurrence of a composite event of renal injury, which includes proteinuria, hypertension and chronic kidney disease (CKD). A predictive model was developed using a Cox proportional hazards model and evaluated by C-statistics.

Results

Renal pelvic dilatation (RPD) was classified into two groups [Grades 1-2 (n = 255) versus Grades 3-4 (n = 192)]. The median follow-up time was 6.4 years (interquartile range 2.8-12.5). Thirteen patients (2.9%) developed proteinuria, 6 (1.3%) hypertension and 14 (3.1%) CKD Stage 2. All events occurred in patients with RPD Grades 3-4. After adjustment, three covariables remained as predictors of the composite event: creatinine {hazard ratio [HR] 1.27, [95% confidence interval (CI) 1.05-1.56]}, renal parenchyma thickness at birth [HR 0.78(95% CI 0.625-0.991)] and recurrent urinary tract infections [HR 4.52 (95% CI 1.49-13.6)]. The probability of renal injury at 15 years of age was estimated as 0, 15 and 24% for patients assigned to the low-risk, medium-risk and high-risk groups, respectively (P < 0.001).

Conclusion

Our findings indicate an uneventful clinical course for patients with Society for Fetal Urology (SFU) Grades 1-2 ANH. Conversely, for infants with SFU Grades 3-4 ANH, our prediction model enabled the identification of a subgroup of patients with increased risk of renal injury over time.

New trends in voiding cystourethrography and vesicoureteral reflux: Who, when and how?

Vesicoureteral reflux, retrograde flow of urine from the bladder into the upper urinary tract, is one of the most common urological diagnoses in the pediatric population. Diagnosis and subsequent management of urinary reflux have become increasingly debated in the past decade, with divergent opinions over which patients should be evaluated for reflux, and when detected, which children should receive intervention. Although some argue that vesicoureteral reflux is a "phenotype" that often resolves without intervention, others contest that untreated reflux has the potential to cause irreversible renal damage over time. Voiding cystourethrogram images the urethra and bladder during both bladder filling and emptying, as well as the ureters and kidneys when reflux is present, and is considered the gold standard for diagnosing vesicoureteral reflux. Once detected, therapeutic options for urinary reflux are diverse, ranging from observation with or without low-dose antibiotic prophylaxis to a variety of operative interventions. Management should be based on a multitude of factors including patient age, risk of subsequent urinary tract infections, risk of renal parenchymal injury, a given child's projected clinical course and parental preference. Over the past two decades, investigators have elucidated many crucial voiding cystourethrogram findings in addition to grade that provide significant prognostic information and are useful in determining the best course of action for a child on a more individualized basis.