Detection of Vesicoureteral Reflux and Rate of Urinary Tract Infection in Isolated High Grade Prenatal Hydronephrosis: Data from the Society for Fetal Urology (SFU) Hydronephrosis Registry
Gina Lockwood, MD, MS1, Melissa McGrath, BASc2, C.D. Anthony Herndon, MD3, Anne G. Dudley, MD4, Walid Farhat, MD5, Nora G. Kern, MD6, Joshua Chamberlin, MD7, Patricio C. Gargollo, MD8, Rebecca S. Zee, MD3, Sarah A. Holzman, MD9, Luis H. Braga, MD2.
1University of Iowa, Iowa City, IA, USA, 2McMaster University, Faculty of Health Sciences, Hamilton, ON, Canada, 3Children's Hospital of Richmond at Virginia Commonwealth University, Richmond, VA, USA, 4Connecticut Children's Medical Center, Hartford, CT, USA, 5University of Wisconsin, Madison, WI, USA, 6University of Virginia, Charlottesville, VA, USA, 7Loma Linda University, Loma Linda, CA, USA, 8Mayo Clinic, Rochester, MN, USA, 9CHOC Children's, Orange, CA, USA.
Background: Understanding the implications of vesicoureteral reflux (VUR) in patients with prenatally-detected hydronephrosis (PNH) continues to evolve as we gain more data about urinary tract infection (UTI) from eight different institutions. The Urinary Tract Dilation consensus statement recommends obtaining voiding cystourethrogram (VCUG) in patients with high grade hydronephrosis, even in the absence of renal parenchymal abnormalities and ureteral/bladder abnormalities, yet there is significant practice variability. We aimed to determine the rates of VUR and UTI in patients with isolated high grade hydronephrosis without concomitant ureteral dilation.
Methods: Subjects with PNH were prospectively enrolled into the multi-institutional Society for Fetal Urology (SFU) Hydronephrosis Registry. Only patients with high grade (SFU grades 3 and 4) hydronephrosis on ultrasound within the first three months of life who also had a voiding cystourethrogram were included. We excluded those with other pertinent genitourinary anomalies. Patient information including sex, circumcision status, radiographic findings, and use of antibiotic prophylaxis were recorded. The proportion of patients with VUR and UTI were calculated, and Fisher’s exact test was used for comparison of outcomes. UTI was defined as positive pyuria with a single organism > 50,000 CFU/mL collected on midstream clean catch or catheterized specimen.
Results: 1848 patients were enrolled, and 300 met inclusion criteria for analysis. Overall, 75% of patients were male, of which 50% were circumcised. The overall rate of VUR was 19.3% (n=58), of which 28% were low grade (I-II) and 72% were high grade (III-V). The rates of VUR were similar between SFU grades 3 (19%) and 4 (21%), (p=0.64). The presence of renal asymmetry or increased renal echogenicity on ultrasonography did not differ between those with and without VUR (1.7% vs. 5% (p=0.48) and 17.2% vs. 17.8% (p=1.0), respectively). The UTI rate was significantly higher in patients with VUR than in those without VUR (29% vs. 10%, p=0.01). The rate of antibiotic prophylaxis was higher in the VUR group than in the non-VUR group (64% vs. 29%) (p<0.01). Of the patients with VUR, 74% were male, and there was no significant difference in the rate of UTI when stratified by sex, regardless of VUR status. Figure 1 shows the rates of UTI stratified by presence or absence of VUR for each grade of hydronephrosis.
Conclusions: We found that the rate of VUR in patients with isolated high grade PNH was 19%, which is consistent with prior studies. We did identify a significantly higher rate of UTI in those patients with VUR, despite 2/3 of them being on antibiotic prophylaxis, compared to those without VUR. We do recognize a possible overestimation of the rate of UTI based on its relaxed definition in our study. Given these data, even in the absence of ureteral dilation, clinicians should consider VCUG in patients with SFU grade 3 and 4 hydronephrosis in order to accurately assess UTI risk. 
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