Vesicoureteral reflux is retrograde passage of urine from the bladder back into the ureter and sometimes also into the renal collecting system, depending on severity. Reflux predisposes to urinary tract infection, often recurrent. Evaluation includes ultrasonography of the kidneys, ureters, and bladder before and after voiding, and then fluoroscopic voiding cystourethrography (VCUG). Treatment depends on the cause and severity.
Etiology of VUR
Vesicoureteral reflux (VUR) is most often due to congenital anomalous development of the ureterovesical junction. Incomplete development of the intramural ureteral tunnel causes failure of the normal flap valve mechanism at the ureterovesical junction, thus permitting reflux of bladder urine into the ureter and renal pelvis. Reflux can occur even when the tunnel is ordinarily sufficient if bladder pressure increases due to bladder outlet obstruction or dysfunctional voiding. Dysfunctional voiding includes infrequent voiding, constipation, or both, which may prolong resolution of VUR.
Pathophysiology of VUR
Reflux of urine from the bladder into the ureter may damage the upper urinary tract by bacterial infection and occasionally by increased hydrostatic pressure. Bacteria in the lower urinary tract can easily be transmitted by reflux to the upper tract, leading to recurrent parenchymal infection with potential scarring. Renal scarring can eventually cause hypertension and sometimes renal dysfunction. VUR is a common cause of urinary tract infection (UTI) in children; about 30 to 40% of infants and toddlers with urinary tract infection (UTI) have VUR (1).
Pathophysiology reference
1. Hoberman A, Charron M, Hickey RW, Baskin M, Kearney DH, Wald ER. Imaging studies after a first febrile urinary tract infection in young children. N Engl J Med. 2003;348(3):195-202. doi:10.1056/NEJMoa021698
Symptoms and Signs of VUR
Children typically present with a history of fetal hydronephrosis or febrile UTI, or they are discovered to have VUR after undergoing screening tests done because they have a sibling with VUR. Up to 25% of siblings can have VUR. As a result, parents may opt to screen asymptomatic siblings.
Rarely, children present with hypertension, which is more commonly a long-term consequence of renal scarring.
Children with UTI may have fever, abdominal or flank pain, dysuria, frequency, urgency, wetting accidents, or rarely hematuria.
Some children do not have symptoms.
Diagnosis of VUR
Ultrasonography
Voiding cystourethrography (VCUG)
Sometimes radioisotope scan
Urinalysis and culture are done to detect infection. In infants and young children, a catheterized specimen is usually required.
Evaluation includes ultrasound of the kidneys, ureters, and bladder before and after voiding, and then fluoroscopic VCUG. Renal ultrasound is used to evaluate kidneys for size, hydronephrosis, and scarring. VCUG is used to diagnose VUR and to evaluate for other bladder anomalies. A radioisotope cystogram (radionuclide cystography) may be used to monitor reflux. Renal cortical involvement with acute infection or scarring is best diagnosed with succimer (dimercaptosuccinic acid) nuclear scans when indicated. Urodynamic studies, when appropriate, may show elevated intravesical pressure.
Reflux findings on VCUG are graded on a scale from I to V (see table Grades of Vesicoureteral Reflux). The degree of reflux can be affected by bladder capacity and bladder dynamics:
Mild: Grades I and II
Moderate: Grade III
Severe: Grades IV and V
Grades of Vesicoureteral Reflux*
Grade | Characteristics |
|---|---|
I | Only the ureters are involved; the renal pelvis is not. |
II | Reflux reaches the renal pelvis, but the calyces are not dilated. |
III | The ureter and renal pelvis are dilated, with minimal or no blunting of calyces. |
IV | Dilation increases, and the sharp angle of the calyceal fornices is obliterated. |
V | The ureter, pelvis, and calices are grossly dilated. Papillary impressions frequently are absent. |
* As defined by the International Reflux Study Committee. | |
Lebowitz RL, Olbing H, Parkkulainen KV, et al. International system of radiographic grading of vesicoureteric reflux. International Reflux Study in Children. Pediatr Radiol. 1985:15(2):105–109. doi:10.1007/BF02388714 | |
(See also the American Urological Association's 2017 Management and Screening of Primary Vesicoureteral Reflux in Children guidelines.)
Treatment of VUR
Sometimes antibiotic prophylaxis
Sometimes injection of a bulking agent or ureteral reimplantation
Mild to moderate vesicoureteral refluxoften resolves spontaneously over months to several years. It is very important to keep children free of infection. Previously, children with mild to moderate VUR were given daily antibacterial prophylaxis, but there is currently no consensus on this practice. Most pediatric urologists recommend prophylactic antibiotics for severe VUR at all ages, for VUR grades III to V in children trimethoprim/sulfamethoxazole at bedtime, nitrofurantoin at dinnertime, or cephalexin twice daily.
Severe vesicoureteral refluxaccompanied by high intravesical pressures is treated with anticholinergic medications (eg, oxybutynin, solifenacin succinate) and rarely surgery (such as botulinum toxin injection or bladder augmentation). Patients with bowel and bladder dysfunction benefit from behavioral modification with or without biofeedback.
Symptomatic reflux (recurrent infections, impaired renal growth, renal scarring, or bladder dysfunction) is treated with endoscopic injection of a bulking agent (eg, dextranomer/hyaluronic acid) or ureteral reimplantation.
Monitoring
History, physical examination (including blood pressure measurement), laboratory testing with urinalysis (to look for hematuria and proteinuria) and serum creatinine, and imaging using VCUG and ultrasound are done at regular intervals depending on the child's age and on the severity of the reflux and associated complications. Typically, children < 2 years have an ultrasound every 4 to 6 months (more frequently in children with significant nephropathy visible on ultrasound); older children have an ultrasound every 6 to 12 months. VCUGs may be repeated every 1 to 2 years (longer intervals for higher grade VUR, bilateral VUR, and/or older children).
In addition, toilet-trained children should be assessed at each visit for constipation and infrequent voiding, incontinence, urinary urgency, and enuresis, which are common signs of elimination dysfunction, and treated as needed with behavioral modification and/or medication therapy.
(See also the American Urological Association's 2017 Management and Screening of Primary Vesicoureteral Reflux in Children guidelines.)
Key Points
Vesicoureteral reflux (VUR) is most often due to congenital anomalous development of the ureterovesical junction.
Reflux of urine from the bladder into the ureter may cause bacterial infection of the upper urinary tract; about 30 to 40% of infants and toddlers with urinary tract infection have VUR.
Diagnose by using VCUG.
Monitor by using serial ultrasounds and VCUGs.
Mild to moderate VUR often resolves spontaneously, but more serious disease may require surgical intervention.
Children with newly diagnosed VUR are given prophylactic antibiotics depending on the severity and clinical course.
Assess toilet-trained children for dysfunctional elimination and treat them appropriately.
