VUR exposes the kidney to increased hydrodynamic pressure during voiding and increases the likelihood of renal infection due to incomplete emptying of the ureter and bladder (see Chapter 114). Reflux nephropathy refers to development and progression of renal scarring. This is a particular risk if VUR is associated with a urinary tract infection (UTI) or obstruction. Although a single UTI may result in renal scarring, the incidence is higher in children with recurrent UTIs. Renal dysplasia is associated with congenital VUR. Because of increasing use of maternal-fetal ultrasonography, a number of newborns are now identified with VUR before UTI has occurred, creating opportunities for early intervention and prevention strategies. Duplication of the ureters, with or without an associated ureterocele, may obstruct the upper collecting system. Often the ureter draining the lower pole of a duplicated renal unit has VUR. Neurogenic bladder is accompanied by VUR in up to 50% of affected children. VUR may also be due to increased intravesicular pressure when the bladder outlet is obstructed from inflammation of the bladder (cystitis) or by acquired bladder obstruction.
VUR is most often identified during radiologic evaluation following a UTI (see Chapter 114). The younger the patient with UTI, the more likely VUR is present. No clinical signs reliably differentiate children with UTI with and without VUR.
An imaging study can be performed after initiation of UTI treatment with no need to wait days or weeks before performing the test. Renal ultrasound (RUS) is the best study to evaluate the urinary tract in children. A voiding cystourethrogram (VCUG) or radionuclide cystogram (NCG) is performed to detect urethral/bladder abnormalities and/or VUR. Recent American Academy of Pediatrics guidelines for infants with a first UTI between 2 and 24 months of age recommend a VCUG if an RUS reveals hydronephrosis, scarring, or other findings suggestive of either high grade VUR or obstructive uropathy and in other atypical or complex clinical circumstances. VCUG should also be performed if there is a recurrence of a febrile UTI. Although the VCUG provides additional anatomic detail, the NCG may detect more children with mild VUR and involves less radiation. An international grading system has been used to describe reflux (Fig. 167-1).The incidence of renal scarring in patients with low-grade VUR is low (15%) and increases with grade IV or V reflux (65%). Grade I or II VUR is likely to resolve without surgical intervention, but VUR resolves in less than 50% grade IV or V. Nuclear renal scanning best identifies renal scars.
Controversy remains about whether long-term prophylactic antibiotic therapy (trimethoprim-sulfamethoxazole ornitrofurantoin) is indicated in mild to moderate VUR. It isoptional in this population and may be particularly useful inchildren with high-grade VUR and/or recurrent symptomatic
Figure 167-1 International classification of vesicoureteral reflux.
Grade I: into a nondilated ureter; grade II: into the pelvis and calyces without dilation; grade III: mild to moderate dilation of the ureter, renal pelvis, and calyces with minimal blunting of the fornices; grade
IV: moderate ureteral tortuosity and dilation of the pelvis and calyces; grade V: gross dilation of the ureter, pelvis, and calyces; loss of papillary impressions; and ureteral tortuosity. (From Wein A, Kavoussi L, Novick A, et al: Campbell-Walsh Urology, ed 9, Philadelphia, 2007, Saunders.)