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Prof. Dr. Ali Avanoğlu
Vesicoureteral Reflux (VUR) • Basics

Unilateral and Bilateral VUR: Does It Make a Difference?

Vesicoureteral reflux (VUR) can be present in a single ureter or in both at once. Bilateral reflux, particularly at high grades, somewhat lowers the chance of spontaneous resolution and calls for closer attention during follow-up, since both kidneys are at risk at the same time; however, it is not on its own a reason for surgery.

Who this is forFamilies whose child has bilateral reflux, or who are in the situation of 'one side resolved, the other is still there'
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ByProf. Dr. Ali AvanoğluUpdated
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unilateral and bilateral reflux
01 · What do unilateral and bilateral reflux mean?02 · Does bilaterality affect spontaneous resolution?03 · What it means for kidney health04 · Treatment decisions and technical differences05 · Practical differences for families during follow-up
In brief5 madde
  • What do unilateral and bilateral reflux mean?: Each kidney has its own ureter and its own opening into the bladder; the valve mechanism on each side is independent of the other.
  • Does bilaterality affect spontaneous resolution?: It does, but less than grade does.
  • What it means for kidney health: This is where the real difference appears.
  • Treatment decisions and technical differences: The principles of treatment do not change: protection from infection, correction of bladder-bowel dysfunction (BBD), and, when needed, endoscopic injection or…
  • Practical differences for families during follow-up: In bilateral reflux, both kidneys are followed separately: the size and dilation of each kidney on ultrasound, each kidney's share of function on DMSA, and the grade…
01

What do unilateral and bilateral reflux mean?

Each kidney has its own ureter and its own opening into the bladder; the valve mechanism on each side is independent of the other. Because of this, reflux can occur only on the right, only on the left, or on both sides at once, and the grade can differ between the two sides.

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  • On the VCUG, which side has reflux and the grade of each side are recorded separately; a result such as 'grade 2 on the right, grade 4 on the left' is common. The literature reports that a significant proportion of children with reflux — roughly a third to a half, depending on the series — have both sides affected.
  • As important as the number of sides affected is, which side it is on is equally unimportant; being on the right or the left does not change the course. What matters is the grade on that side and the condition of that kidney.
02

Does bilaterality affect spontaneous resolution?

It does, but less than grade does. In the models used to predict the likelihood of spontaneous resolution, bilaterality is one of the factors, along with high grade and diagnosis at an older age, that lowers the chance of resolution. The effect is most evident at high grades; the likelihood of resolution is lower for bilateral grade 4–5 reflux than for unilateral disease.

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  • For low-grade bilateral reflux, on the other hand, the outlook is more optimistic; in most of these children, both sides resolve over the years. But the two sides do not have to resolve at the same rate: it is common — and not on its own a cause for concern — for follow-up imaging to show that reflux has disappeared on one side while it persists on the other.
  • For this reason, in guideline risk groupings, low-grade bilateral reflux is treated one step higher than unilateral reflux; monitoring continues, but more closely, and the decision to start antibiotic prophylaxis is made more readily.
03

What it means for kidney health

This is where the real difference appears. In unilateral reflux, even if infection-related scarring develops in one kidney, the other kidney is healthy and largely preserves overall function; long-term blood pressure and kidney function problems are rare. In bilateral reflux, both kidneys are at risk at the same time, and any resulting damage is not compensated for.

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  • Long-term high blood pressure and reduced kidney function are linked less to reflux itself than to extensive, bilateral scarring; advanced kidney failure due to reflux nephropathy is now rare and occurs mainly in this group. This is why, in bilateral reflux, knowing each kidney's split function through a DMSA renal scan, along with annual blood pressure and urine protein checks, becomes even more important.
  • On the other hand, there are many children with bilateral reflux whose kidneys are both completely healthy. The number of sides affected raises the risk; it does not determine the outcome.
04

Treatment decisions and technical differences

The principles of treatment do not change: protection from infection, correction of bladder-bowel dysfunction (BBD), and, when needed, endoscopic injection or reimplantation. Bilaterality does not change the order of these steps, but it does bring closer follow-up and the threshold for intervention somewhat earlier.

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  • Endoscopic injection can be applied to both sides in the same session, under the same anesthetic. In reimplantation, however, the choice of technique becomes important depending on how many sides are involved: the intravesical (Cohen) technique is well suited to correcting both sides together; the extravesical (Lich-Gregoir) technique carries a risk of temporary voiding difficulty when applied bilaterally, so most teams prefer the intravesical approach or a staged correction for bilateral cases.
  • New reflux appearing on the opposite side after surgery for unilateral VUR is reported in about 5–10% of cases in the literature; this is usually low-grade and resolves on its own. If the opposite side already has low-grade reflux beforehand, whether it is corrected in the same session is planned through the joint assessment of both specialists before surgery.
05

Practical differences for families during follow-up

In bilateral reflux, both kidneys are followed separately: the size and dilation of each kidney on ultrasound, each kidney's share of function on DMSA, and the grade on each side on follow-up imaging. Resolution on one side does not end follow-up; the plan continues for the side that persists.

  • Not starting antibiotics for any fever, regardless of which side is affected, without first obtaining a culture
  • Recording the size of each kidney separately on the annual ultrasound
  • Annual blood pressure measurement and a check for protein in the urine if scarring has been found
  • Continuing the follow-up plan for the other side even if one side has resolved
  • To determine which kidney was affected after a febrile infection, repeating the DMSA scan 4–6 months later comes up more often in bilateral cases. In adolescence and adulthood, particularly for girls with bilateral scarring, blood pressure and pregnancy counseling are a natural part of follow-up; in our practice, this transition continues with the same physicians, so follow-up is never interrupted.
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Frequently asked questions
Is bilateral reflux more dangerous than unilateral reflux?
It calls for somewhat closer attention, because with both kidneys at risk there is no compensation for any resulting damage. But how dangerous it is depends less on the number of sides than on the grade of reflux, how often infections occur, and whether there is kidney scarring. Most children with bilateral, low-grade reflux improve with monitoring alone.
Can unilateral reflux spread to the other kidney?
Reflux is not a contagious process; it does not 'spread' from one ureter to the other. However, reflux that appears unilateral on a given study may have been present at a low level on the other side that day and been missed, or the opposite side may show mild reflux after surgery on one side because of a change in bladder pressure. These are generally mild and resolve on their own.
One side resolved, the other is still there; what happens next?
This is a common and expected situation. The decision for the persisting side is based on that side's grade, the child's age, infection history, and the condition of the kidney; the resolved side does not affect the plan. In most cases, monitoring continues, and if needed, endoscopic injection is given to that side alone.
If surgery is needed, are both sides done in the same session?
Usually, yes. Endoscopic injection and intravesical (Cohen) reimplantation can be performed on both sides in the same session. If the extravesical technique is to be used bilaterally, because of the risk of temporary voiding difficulty, the choice of technique or a staged correction is planned by the team before surgery.
←Previous • BasicsWhat Do VUR Grades (1–5) Mean?Next • BasicsIs VUR Genetic? Sibling and Child Screening→
Related pagesFull index →
BasicsWhat Do VUR Grades (1–5) Mean?Vesicoureteral reflux (VUR) is classified into five grades, from 1 to 5; the grade describes how far up the urine flows and to what extent the ureter and the kidney's collecting system are dilated. The grade is determined with a VCUG (voiding cystourethrogram) and is the strongest predictor of spontaneous resolution; however, it does not determine the treatment decision on its own.Treatment pathwaysDoes Vesicoureteral Reflux Resolve on Its Own? Active SurveillanceFor families who have just received a diagnosis of vesicoureteral reflux (VUR), the first question is usually, 'Will it go away on its own?' For most children, the answer is yes — but the likelihood depends on the grade of reflux, the child's age, and other contributing factors. This page explains how resolution happens, in which children it is more likely, and what 'active surveillance' means.Treatment pathwaysUreteral Reimplantation (Anti-Reflux Surgery): Cohen, Lich-GregoirUreteral reimplantation, used in vesicoureteral reflux (VUR), reconnects the ureter to the bladder through a new, longer tunnel. This operation, which has the highest success rate among reflux treatments, eliminates reflux with roughly 95–98% success in the literature. This page explains the principle behind the surgery, the techniques used, possible complications, and what to expect in hospital.Kidney health and infectionIs Kidney Reflux Dangerous? Reflux Nephropathy and Renal ScarringThe honest answer to “is kidney reflux dangerous?” has two sides: reflux itself is harmless and temporary in most children; what truly matters is whether permanent kidney damage — reflux nephropathy, renal scarring — develops alongside a febrile infection. This page explains what scarring is, its two different types, how it is detected with DMSA, which children are at higher risk, and what can be prevented.
Vesicoureteral Reflux (VUR) topic clustersMain treatment page →
Basics 6Diagnosis and evaluation 6By age and special situations 5Bladder and bowel 5Treatment pathways 10Kidney health and infection 5After treatment and follow-up 6
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