Ultrasound Detection of Vesicoureteral Reflux in Children

Pediatric voiding cystourethrography: An essential examination for urologists but a terrible experience for children

Voiding cystourethrography is the most important fluoroscopic examination in pediatric urology for the investigation of lower urogenital tract diseases, such as vesicoureteral reflux or urethral stricture. However, this invasive procedure imposes a significant burden on children and their parents, and recently there has been a paradigm shift in the diagnosis and treatment of vesicoureteral reflux. In the 2011 revision, the American Academy of Pediatrics guidelines on urinary tract infection recommended abandoning routine voiding cystourethrography after the first febrile urinary tract infection. In 2014, the randomized intervention for children with vesicoureteral reflux study recommended discontinuation of routine continuous antibiotic prophylaxis for vesicoureteral reflux. The time is now ripe to radically reconsider indications for voiding cystourethrography and the procedure itself.

Diagnostic accuracy of contrast-enhanced voiding urosonogram using second-generation contrast with harmonic imaging (CEVUS-HI) study for assessment of vesicoureteral reflux in children: a meta-analysis

PURPOSE

To assess the diagnostic accuracy and safety of contrast-enhanced voiding urosonogram using second-generation contrast with harmonic imaging (CEVUS-HI) in detecting vesicoureteral reflux (VUR) among children.

METHODS

A systematic literature search was performed in March 2018. Relevant comparative studies from Medline, EMBASE, World of Science, Scopus, CENTRAL, WHO trial registry and Clinicaltrials.gov were identified and appraised using QUADAS-2. Diagnostic accuracy parameters were determined using VCUG as the reference standard. Adverse effects related to ultrasound contrast were summarized. The heterogeneity and inter-study variability were determined. After appropriate subgroup diagnostic accuracy parameters were investigated, summarizing receiver operator characteristics was constructed using the bivariate model meta-regression to determine the area under the curve (AUC).

RESULTS

A total of 12 studies with low-high risk of bias, including 1917 ureteral units from 953 patients were assessed for this meta-analysis. The included studies reported no serious adverse events associated with the ultrasound contrast. The pooled diagnostic accuracy parameters of CEVUS-HI in detecting VUR amongst children were: sensitivity 90.43 (95% CI 90.36-90.50), specificity 92.82 (95% CI 92.76-92.87), the calculated (+) likelihood-ratio 12.59 (95% CI 12.49-12.68), (-) likelihood-ratio of 0.103 (95% CI 0.102-0.104) and extrapolated pooled diagnostic odds-ratio was 122.12 (95% CI 120.75-123.49). Heterogeneity with interstudy variability was noted (p < 0.0001, I-squared > 70%). The AUC was determined to be 0.965 for VUR detection.

CONCLUSIONS

The pooled diagnostic accuracy parameters from low-moderate quality of evidence have illustrated that the CEVUS-HI study has an excellent safety profile and acceptable diagnostic accuracy. It may be considered as an alternative diagnostic modality for assessment of VUR among children.

Contrast-enhanced Voiding Urosonography for Vesicoureteral Reflux Diagnosis in Children

Contrast-enhanced voiding urosonography (ceVUS) is a dynamic imaging technique that makes it possible to study the structure of the urinary tract after the administration of intravesical contrast material. Initially, ceVUS was indicated mainly to study vesicoureteral reflux (VUR); however, since the ability of ceVUS to depict the structure of the urethra was demonstrated in both sexes, ceVUS is now indicated for examination of the entire urinary tract. The main benefit of ceVUS is that it does not use ionizing radiation. In recent years, fundamental changes have occurred in the understanding of VUR. The lessening effect of VUR and the low rate of occurrence of urethral pathologic conditions have given rise to changes in the indications for tests for these conditions. In addition to being able to help confirm a diagnosis of VUR, the ceVUS technique can be used to depict obstructive and nonobstructive urethral pathologic conditions, as well as normal variants, on high-quality images. Furthermore, ceVUS enables real-time assessment of voiding function. For these reasons, ceVUS should be not only an alternative to voiding cystourethrography, but also the technique of choice for the study of the entire urinary tract in pediatric patients. Online supplemental material is available for this article. ^©RSNA, 2017.

Voiding urosonography with second-generation contrast as a main tool for examining the upper and lower urinary tract in children. Pilot Study

INTRODUCTION

In this series, we analyse the diagnostic efficacy of serial voiding urosonography (VUS) with second-generation contrast, combined harmoniously and specifically with contrast technology, in the examination of the urinary tract in children. This examination includes the diagnosis and follow-up for vesicoureteral reflux (VUR) and urethral disorders, mainly those of the posterior urethral valve (PUV).

PATIENTS AND METHODS

After obtaining informed consent, a prospective study was conducted using urosonography with second-generation contrast (sulphur hexafluoride microbubbles, SonoVue®) from November 2014 to October 2015 (1 year) in paediatric patients with suspected VUR or PUV impairment. For patients with a high suspicion of VUR and in cases of PUV, we also conducted simultaneous voiding cystourethrography (VCUG).

RESULTS

We studied 40 patients (80 renal units) between the ages of 2 months and 13 years (median age, 14 months). The indication for the test was a suspected VUR (36 patients, group A) and PUV follow-up (4 patients, group B). The test was correlated with VCUG in 16 patients (12 cases with high suspicion of VUR in group A and with 4 cases of PUV in group B). The visualisation of the urethra was appropriate in cases of dilation or urethral stricture. For 3 of these patients with bilateral VUR demonstrated in the serial VUS, the VCUG showed only unilateral VUR in 2 of the patients and no VUR in 1 of the patients (κ=.73).

DISCUSSION

We have shown that the visualisation of the urethra is no longer a limitation and that serial VUS can be superior to conventional VCUG in diagnosing VUR.

A comparison of echo-enhanced voiding urosonography with X-ray voiding cystourethrography in the first year of life

BACKGROUND

Second-generation echo-enhanced voiding urosonography (VUS) with improved contrast-specific ultrasound (US) techniques is increasingly being used for vesicoureteric reflux (VUR) detection.

AIM

To compare VUS with X-ray voiding cystourethrography (VCUG) and to evaluate the predictive value of pelvicalyceal dilatation for detecting VUR in the first year of life.

MATERIALS AND METHODS

Sixty-six children younger than one were investigated by US, VUS and VCUG. VCUG represented the reference method for VUR detection.

RESULTS

According to VCUG, VUR was present in 16/132 (12%) renal units. VUS confirmed all these and additionally revealed VUR in 26 renal units (all together 42/132 (32%) renal units with VUR). It should be noted that all VUR detected only with VUS and missed by VCUG were of grades II and III. In 27/92 (29%) US normal and in 15/40 (37%) renal units with pelvicalyceal dilatation, VUR was detected by VUS.

CONCLUSION

We believe that VUS could safely replace VCUG in VUR detection in infants, with no regard to the degree of abnormality of the upper urinary tract seen on US. VCUG should be limited only to cases where bladder and/or urethra pathology are suspected.

Noninvasive assessment of antenatal hydronephrosis in mice reveals a critical role for Robo2 in maintaining anti-reflux mechanism

Antenatal hydronephrosis and vesicoureteral reflux (VUR) are common renal tract birth defects. We recently showed that disruption of the Robo2 gene is associated with VUR in humans and antenatal hydronephrosis in knockout mice. However, the natural history, causal relationship and developmental origins of these clinical conditions remain largely unclear. Although the hydronephrosis phenotype in Robo2 knockout mice has been attributed to the coexistence of ureteral reflux and obstruction in the same mice, this hypothesis has not been tested experimentally. Here we used noninvasive high-resolution micro-ultrasonography and pathological analysis to follow the progression of antenatal hydronephrosis in individual Robo2-deficient mice from embryo to adulthood. We found that hydronephrosis progressed continuously after birth with no spontaneous resolution. With the use of a microbubble ultrasound contrast agent and ultrasound-guided percutaneous aspiration, we demonstrated that antenatal hydronephrosis in Robo2-deficient mice is caused by high-grade VUR resulting from a dilated and incompetent ureterovesical junction rather than ureteral obstruction. We further documented Robo2 expression around the developing ureterovesical junction and identified early dilatation of ureteral orifice structures as a potential fetal origin of antenatal hydronephrosis and VUR. Our results thus demonstrate that Robo2 is crucial for the formation of a normal ureteral orifice and for the maintenance of an effective anti-reflux mechanism. This study also establishes a reproducible genetic mouse model of progressive antenatal hydronephrosis and primary high-grade VUR.