Uroepithelial Thickening on Sonography Improves Detection of Vesicoureteral Reflux in Children with First Febrile Urinary Tract Infection

Roles for urothelium in normal and aberrant urinary tract development

Congenital anomalies of the kidney and urinary tract (CAKUTs) represent the leading cause of chronic kidney disease and end-stage kidney disease in children. Increasing evidence points to critical roles for the urothelium in the developing urinary tract and in the genesis of CAKUTs. The involvement of the urothelium in patterning the urinary tract is supported by evidence that CAKUTs can arise as a result of abnormal urothelial development. Emerging evidence indicates that congenital urinary tract obstruction triggers urothelial remodelling that stabilizes the obstructed kidney and limits renal injury. Finally, the diagnostic potential of radiological findings and urinary biomarkers derived from the urothelium of patients with CAKUTs might aid their contribution to clinical care.

Updated Italian recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children

AIM

Our aim was to update the recommendations for the diagnosis, treatment and follow-up of the first febrile urinary tract infection in young children, which were endorsed in 2012 by the Italian Society of Pediatric Nephrology.

METHODS

The Italian recommendations were revised on the basis of a review of the literature published from 2012 to October 2018. We also carried out an ad hoc evaluation of the risk factors to identify children with high-grade vesicoureteral reflux or renal scarring, which were published in the previous recommendations. When evidence was not available, the working group held extensive discussions, during various meetings and through email exchanges.

RESULTS

Four major modifications have been introduced. The method for collecting urine for culture and its interpretation has been re-evaluated. We have reformulated the algorithm that guides clinical decisions to proceed with voiding cystourethrography. The suggested antibiotics have been revised, and we have recommended further restrictions of the use of antibiotic prophylaxis.

CONCLUSION

These updated recommendations have now been endorsed by the Italian Society of Pediatric Nephrology and the Italian Society for Pediatric Infectivology. They can also be used to compare other recommendations that are available, as a worldwide consensus in this area is still lacking.

The uroplakin plaque promotes renal structural integrity during congenital and acquired urinary tract obstruction

Urinary tract obstruction represents a common cause of kidney injury across the human life span, resulting in chronic kidney disease and end-stage renal disease. Yet, the extent of obstructive renal damage can be heterogeneous between individuals, implying the existence of unknown mechanisms that protect against or accelerate kidney injury. In this study, we investigated the role of urothelial remodeling in renal adaptation during congenital and acquired obstruction. In the Megabladder ( Mgb-/-) model of congenital obstruction and unilateral ureteral ligation model of acute obstruction, progressive hydronephrosis is strongly associated with dynamic reorganization of the renal urothelium, which elaborates a continuous uroplakin (Upk) plaque. This led us to postulate that the Upk plaque prevents parenchymal injury during urinary tract obstruction. To test this hypothesis, we interbred Mgb-/- and Upk1b-/- mice, which lack the critical Upk1b subunit for Upk plaque formation. Upk1b-/-; Mgb-/- mice experienced an accelerated onset of bilateral hydronephrosis with severe (>67%) parenchymal loss, leading to renal failure and mortality in adolescence. To investigate the function of the renal Upk plaque during acute obstruction, we destabilized the Upk plaque by Upk1b deletion or genetically depleted Upk+ cells following unilateral ureteral obstruction. Both of these strategies accelerated renal parenchymal loss following ureteral ligation, attesting to a conserved, stabilizing role for Upk plaque deposition in the acutely obstructed kidney. In aggregate, these complementary experiments provide the first evidence that the Upk plaque confers an essential, protective adaptation to preserve renal parenchymal integrity during congenital and acquired urinary tract obstruction.

Uroepithelial thickening improves detection of vesicoureteral reflux in infants with prenatal hydronephrosis

INTRODUCTION

Postnatal evaluation of prenatal hydronephrosis (PNH) often includes a voiding cystourethrogram (VCUG) for VUR assessment. Despite limited supporting data, VCUG is currently recommended if postnatal renal and bladder ultrasound (RBUS) reveals moderate/severe hydronephrosis (HN) or hydroureter (HU). Recent studies have shown VUR is more accurately diagnosed by using certain sonographic findings as criteria for obtaining VCUG. Uroepithelial thickening (UET) of the renal pelvis is a finding associated with high-grade vesicoureteral reflux (HGVUR); however, the clinical significance of UET with PNH has not been studied.

OBJECTIVE

We sought to determine if the presence of UET implies increased risk for VUR, and to investigate whether UET can improve the test characteristics of RBUS for VUR.

STUDY DESIGN

We retrospectively analyzed postnatal RBUS and VCUG findings in infants ≤30 days undergoing evaluation for "prenatal hydronephrosis" over an 11-year period. We used logistic regression to identify factors associated with VUR. Test characteristics of RBUS for HGVUR were compared based on the presence of UET and two criteria sets to define abnormal RBUS. Criteria set 1 consisted of HN SFU grade 3-4 and/or HU; criteria set 2 was defined by the presence of two of following: UET, HU, duplication, and/or renal dysmorphia.

RESULTS

Of 135 patients, 39 (29%) had VUR, of whom 16 (41%) had HGVUR. UET was significantly associated with VUR (p < 0.001), and the sensitivity for HGVUR based on UET alone was 94%. On multivariable analysis, UET, HU, duplication, and renal dysmorphia remained significant independent predictors of HGVUR. Compared to criteria 1, using criteria 2 resulted in 43 fewer VCUGs, and significant improvement in sensitivity and specificity for HGVUR (Table).

DISCUSSION

Consistent with previous studies, HN alone on postnatal RBUS has little value in predicting the presence or severity of VUR. This study is the largest known series to evaluate UET in the setting of PNH, and our results demonstrate that UET, as well as HU, duplication and renal dysmorphia, are independent sonographic findings predicting HGVUR. Using our proposed criteria, the probability of HGVUR is fourfold more than the prevalence described in the literature, and importantly, when compared to the criteria recommended by the SFU and AUA, would have resulted in 53% fewer VCUGs while missing zero cases of HGVUR.

CONCLUSION

In infants with PNH, the sonographic findings of UET, HU, duplication and renal dysmorphia independently indicate greater risk of HGVUR, and the sensitivity and specificity of RBUS for HGVUR is markedly improved when at least two of the four are present.