Distal Ureteral Diameter Ratio is Predictive of Breakthrough Febrile Urinary Tract Infection

Diagnosis and management of vesicoureteral reflux are difficult to treat to the high associated risk of recurrent tract infections and renal scarring. Because of this, treatment goals include prevention of febrile infections, avoidance of renal injury, and minimizing morbidity of treatment and follow-up.¹ Children are at higher risk for recurrent pyelonephritis as well as potential sequelae from renal injury. The distal uretal diameter ratio (UDR) has high interrater reliability and has been shown to be predictive of spontaneous reflux resolution. The goal of this study was to evaluate UDR on initial diagnostic cystogram and risk of breakthrough febrile urinary tract infection (UTI). The clinicians in this experiment hypothesized children with greater UDR would have an increased risk of febrile UTI.

This was a retrospective study that identified 140 children with primary VUR between 1990 and 2010. Ureteral diameter ratio was computed by measuring largest ureteral diameter within the pelvis and dividing by the distance between L1 and L3 vertebral bodies. Patient demographics, UTI history, VUR grade, presence or absence of BBD and subsequent imaging were assessed and tested in univariate and multivariable analyses.

Primary outcome was breakthrough febrile urinary tract infections.

The results of the study showed that vesicoureteral reflux was grade 1 to 2 in 64 patients (45.7%), grade 3 in 50 (35.7%), grade 4 in 16 (11.4%) and grade 5 in 10 (7.2%). Of the 140 children (112 girls and 28 boys), 40 (28.6%) experienced breakthrough febrile urinary tract infections. 45 (32.1%) experienced spontaneous resolution of VUR at a mean +/- SD interval of 2.7 +/- 2.7 years, and 95 (67.9%) underwent surgical correction of VUR during clinical follow up at a mean +/- SD of 3.4 +/- 2.6 years from initial diagnosis. Ureteral diameter ratio was significantly greater in children with vs without breakthrough febrile infections.

In conclusion, children with primary vesicoureteral reflux associated with an increased UDR are at greater risk for febrile UTI. Ureteral diameter ratio then provides as a valuable prognostic information about risk of recurrent pyelonephritis and may assist in clinical decision-making. Some limitations that the authors noted was the retrospective nature of the study design, false-positive specimens, and change of required bacterial colony count from 100,000 to 50,000.

Written by: Zhamshid Okhunov, MD, University of California Irvine

References:
1. Peters CA, Skoog SJ, Arant BS Jr et al: Summary of the AUA guideline on management of primary vesicoureteral reflux in children. J Urol 2010; 184: 1134

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