Vesicoureteric Reflux

Vesicoureteric reflux is retrograde flow of urine from the bladder into the upper urinary tract during bladder filling or voiding. The urine reaches the ureter and, in more severe cases, the renal collecting system. It results from an incompetent or anatomically deficient vesicoureteric junction valve mechanism. It is common in infants and young children.

Its clinical significance is the associated increased risk of urinary tract infection, specifically pyelonephritis, because infected urine is transported retrogradely into the upper renal tract.

Recurrent or severe, high-grade reflux carries a risk of renal scarring. In the most severe, longstanding and inadequately managed cases, it can cause chronic kidney disease.

Management is graded and risk-stratified. It takes account of the reflux grade, the presence or absence of pre-existing renal scarring, and the frequency of recurrent infection.

Classification and pathophysiology

• Primary vesicoureteral reflux is a congenital, intrinsic abnormality of the vesicoureteric junction. It most commonly reflects an abnormally short intramural (within the bladder wall) course of the distal ureter.
• Normally, this segment is compressed against the surrounding bladder musculature during filling and voiding. This acts as a valve and prevents retrograde flow. An inadequate intramural tunnel length produces an incompetent valve and reflux.
• Secondary vesicoureteral reflux occurs with an identifiable underlying predisposing condition. Examples are bladder outlet obstruction, a neurogenic bladder, or significant bladder dysfunction from any cause. Elevated intravesical pressure overcomes the normal valve mechanism. Management is directed at the underlying cause.
• The internationally recognised grading system ranges from grade one (reflux confined to the ureter without dilation) to grade five (severe reflux with marked ureteric and renal pelvicalyceal dilation and tortuosity). It is an essential, standardised framework for severity.
• Grade guides the anticipated natural history and the management approach. Lower grade reflux has a substantially higher rate of spontaneous resolution over time than higher grade reflux.
• There is a well recognised familial predisposition. Risk is substantially increased in siblings and offspring of an affected individual. Routine screening of asymptomatic siblings remains debated, with variation in practice, given the generally favourable natural history of milder disease.

• Urinary tract infection is the commonest presenting feature that prompts identification of reflux. This is particularly febrile urinary tract infection reflecting pyelonephritis.
• The condition is typically identified through the standard, structured imaging investigation after a first febrile urinary tract infection in an infant or young child.
• A proportion of cases are identified antenatally, through hydronephrosis on routine antenatal ultrasound screening. Postnatal micturating cystourethrography then confirms the diagnosis and the grade of reflux.
• Without associated infection, reflux is generally entirely asymptomatic. Reflux in isolation, with no history of urinary tract infection, does not typically produce any direct symptom.
• Its clinical significance lies in the infection risk and, where infection recurs, the subsequent risk of renal scarring. The reflux itself causes no direct symptomatic burden.
• Renal scarring is generally identified by nuclear medicine (DMSA) renal scanning, not by symptoms. Scanning follows a confirmed episode of pyelonephritis or is part of structured, ongoing surveillance in a child with confirmed reflux.
• This complication is largely silent, though potentially clinically significant.

• Micturating cystourethrography is the definitive diagnostic investigation. Contrast is instilled into the bladder via a urethral catheter, with fluoroscopic imaging during filling and voiding. It directly demonstrates and grades the presence and severity of reflux.
• Indications include a first febrile urinary tract infection in an infant, or significant, relevant antenatally identified hydronephrosis.
• Direct radionuclide cystography instils a radioactive tracer into the bladder and images with a gamma camera. It is an alternative with lower radiation exposure than standard micturating cystourethrography, but lower anatomical resolution.
• It is therefore generally preferred for follow-up of previously characterised reflux, where detailed anatomical grading is less critical, rather than for initial diagnosis.
• Nuclear medicine renal scanning (DMSA) assesses for renal cortical scarring. Perform it at initial diagnosis, as a baseline. Repeat it at structured follow-up intervals where indicated by recurrent infection or the initial severity of reflux.
• DMSA informs assessment of any developing complication. In some management protocols, it also informs the intensity of continued management.
• Renal ultrasound cannot directly demonstrate reflux. It is a standard component of assessment, characterising renal size, growth, and any associated structural abnormality.

• Management is graded and risk-stratified by reflux grade, the presence and extent of renal scarring, and the pattern of recurrent infection.
• Lower grade reflux, particularly without significant renal scarring or recurrent infection, is generally managed conservatively. Spontaneous resolution over time is highly likely.
• Higher grade reflux, or reflux with recurrent breakthrough infection or progressive renal scarring, may warrant more active management or intervention.
• Conservative management suits the great majority of lower grade cases. It comprises prompt recognition and treatment of any urinary tract infection, and in selected cases continuous low-dose antibiotic prophylaxis.
• The evidence for and role of routine prophylaxis has evolved considerably and remains under discussion. Contemporary practice generally favours a selective, individualised approach, not routine prophylaxis for every child with confirmed reflux.
• Attend to bladder and bowel dysfunction. Address coexisting constipation, which directly affects bladder function and reflux resolution. Encourage regular, timed voiding and avoidance of voiding postponement.
• This is an important, evidence-based and generally underemphasised component of conservative management. Bladder dysfunction is related to both reflux persistence and infection risk.
• Consider surgical or endoscopic intervention for higher grade reflux, reflux with recurrent breakthrough febrile urinary tract infection despite appropriate conservative management, or progressive renal scarring.
• Endoscopic subureteric injection of a bulking agent is relatively minimally invasive. It augments the deficient valve mechanism and corrects reflux in a substantial proportion of appropriately selected cases.
• Open or laparoscopic ureteric reimplantation gives more definitive, though more invasive, correction. It is generally reserved for higher grade reflux or cases not responding to the endoscopic approach.
• Structured, long-term follow up includes periodic reassessment of reflux status. Lower grade reflux tends to resolve spontaneously, so repeat imaging at structured intervals assesses for this expected resolution.
• Monitor renal growth and function, and blood pressure, given the long-term risk of hypertension with significant renal scarring.
• Investigate and treat any further urinary tract infection promptly.
• The overarching goal is prevention of renal scarring and preservation of long-term renal function through individualised, risk-stratified management.