Vesicoureteral reflux (VUR)
Young children with febrile urinary tract infections (UTIs) may have anatomic abnormalities of the urinary tract, most commonly vesicoureteral reflux (VUR). VUR is a urological condition where urine flows backwards up the ureters from the bladder towards the kidneys. Primary VUR, the most common type, is the result of an abnormal (or immature) configuration of the ureterovesical junction, with failure of the normal flap-valve function. VUR affects an estimated 1 percent of all children at birth, but among high-risk groups (e.g., infants with febrile UTI, prenatal hydronephrosis or a family history of VUR), it can affect between 15 and 70 percent of children.
Although non-invasive testing, such as renal ultrasound, can indicate abnormalities (including hydronephrosis, a condition associated with VUR), the only reliable method for diagnosing VUR is a cystogram, either a radionuclide cystogram (RNC) or a voiding cystourethrogram (VCUG).
For initial diagnosis, VCUG is usually the first choice due to its superior level of anatomic detail. In a VCUG, a radiologist inserts a catheter into the bladder and instills contrast until voiding occurs, fluoroscopically imaging the bladder, urethra and retroperitoneum during both filling and voiding. The VCUG provides anatomic and functional information on many elements of the lower urinary tract beyond VUR presence and grade, including bladder appearance, capacity and emptying, urethral configuration and obstruction, and ureteral insertion location.
When ordering a VCUG study, providers should consider where to refer—a free-standing pediatric hospital vs. a general hospital vs. a pediatric "hospital within a hospital." A recent study published in the journal Pediatric Radiology by Boston Children’s Hospital’s departments of Urology and Radiology compared VCUG reports from dozens of different facilities and found that free-standing pediatric hospitals produce more complete, higher-quality VCUG reports compared to other institutions, potentially reducing the need for repeat testing and patient radiation exposure.
VUR staging and management
If a child has VUR, the VCUG test results will indicate where their condition falls on a scale from grade I (mild) to V (severe) and identify whether both ureters and/or both kidneys are affected. Grade I VUR only reaches the ureter, grade II reaches the non-dilated kidney and grades III-V represent VUR into increasingly dilated ureters and kidneys. Approximately 50 percent of cases are bilateral, and each side is graded separately.
In many cases, VUR will resolve spontaneously, with mild VUR being more likely to resolve than higher grades. Providers can use a VUR resolution rate calculator developed by the Boston Children's Urology Department to predict the probability of a patient’s VUR resolving on its own without surgery, based on a number of predictive parameters.
Though VUR cannot be prevented, the UTIs associated with the condition can be. To prevent UTIs and further reduce the risk of kidney infection, pediatric urologists recommend prescribing low-dose prophylactic antibiotics. Newborns most commonly receive amoxicillin, while older children should receive trimethoprim-sulfamethoxazole, nitrofurantoin or cephalexin.
The “Randomized Intervention for Children with Vesicoureteral Reflux (RIVUR)” study, recently published in the New England Journal of Medicine, demonstrated that antibiotic prophylaxis significantly decreased the incidence of recurrent febrile or symptomatic UTI among children with VUR, compared with placebo. The National Institute of Diabetes and Digestive and Kidney Diseases sponsored this nationwide study, with Boston Children's as a major collaborator.
For children with recurrent febrile UTI despite antibiotic prophylaxis, VUR that persists despite years of surveillance, or very severe VUR that is unlikely to resolve spontaneously, surgery is often recommended. The results of anti-reflux surgery are generally excellent; success rates at Boston Children’s consistently approach 100 percent. More recently, novel, minimally invasive surgical techniques such as robotic, laparoscopic and endoscopic procedures have become available and continue to improve in comparison with accepted open techniques. Boston Children’s Robotic Surgery, Research and Training Program has information about robotic surgery techniques and procedures for pediatric patients, including those with VUR.
With proper management, observation and low-dose antibiotic therapy, many cases of VUR will resolve spontaneously. Once resolved, it is highly unusual for VUR to recur in the absence of additional underlying bladder disease. In high-grade VUR, or for children with breakthrough UTI or failure to resolve despite long-term medical management, surgery is often recommended and is highly successful.