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Vesicoureteral Reflux (VUR) • By age and special situations

Vesicoureteral Reflux in Infants (0–1 Years): Protection and the Outlook for Resolution

In infants, vesicoureteral reflux (VUR) most often comes to light through antenatal kidney enlargement or a first febrile urinary tract infection. In this age group, both the risk of infection-related kidney damage and the chance of spontaneous resolution are at their highest; the plan for the first year therefore combines protection with patient waiting.

Who this is forFamilies whose infant has been diagnosed with vesicoureteral reflux after antenatal kidney enlargement or a febrile urinary tract infection
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ByProf. Dr. Ali AvanoğluUpdated
This page is part of vesicoureteral reflux.Read the full treatment overview on the hub page
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01 · Why is vesicoureteral reflux managed differently in infants?02 · How is reflux discovered in infants?03 · Antibiotic prophylaxis (CAP) in infants: who, and why?04 · What does circumcision offer a male infant?05 · Outlook for resolution in the first year06 · What should you watch for at home?
In brief5 madde
  • Why is vesicoureteral reflux managed differently in infants?: Vesicoureteral reflux in infants under one year differs from that in older children in several ways: high-grade reflux is more common, it occurs more often in male…
  • How is reflux discovered in infants?: Vesicoureteral reflux in infants is discovered through two main routes: postnatal work-up of kidney enlargement detected before birth (antenatal hydronephrosis), and…
  • Antibiotic prophylaxis (CAP) in infants: who, and why?: Antibiotic prophylaxis (CAP; a single nightly dose, about one-quarter to one-third of the treatment dose) is the cornerstone of reflux management in infancy; the goal…
  • What does circumcision offer a male infant?: Circumcision is a simple option that lowers the risk of urinary tract infection in male infants with vesicoureteral reflux, and it is mentioned for this purpose in…
  • Outlook for resolution in the first year: The most encouraging aspect of vesicoureteral reflux in infants is that spontaneous resolution happens fastest in the first years of life; as the child grows, the…
01

Why is vesicoureteral reflux managed differently in infants?

Vesicoureteral reflux in infants under one year differs from that in older children in several ways: high-grade reflux is more common, it occurs more often in male infants, and infection reaches the kidney more easily.

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  • The infant kidney is more vulnerable to pyelonephritis (kidney infection); a febrile urinary tract infection (UTI) can spread more quickly at this age and is more likely to leave permanent scarring. At the same time, an infant's symptoms are silent: fever, irritability, poor feeding, vomiting, or failure to gain weight may be the only signs. For this reason, every unexplained fever in an infant deserves evaluation with a urine culture.
  • In male infants with high-grade reflux at this age, part of the kidney impairment does not come from infection but from a congenital developmental defect (dysplasia). This distinction matters: a congenital injury cannot be prevented, but a new infection-related scar can be. All of our effort in the first year is directed at the latter.
02

How is reflux discovered in infants?

Vesicoureteral reflux in infants is discovered through two main routes: postnatal work-up of kidney enlargement detected before birth (antenatal hydronephrosis), and a first febrile urinary tract infection.

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  • Reflux is found in about 10–20% of infants with antenatal kidney enlargement. The first step after birth is a kidney–bladder ultrasound; findings such as marked enlargement, a visible ureter (the urine channel between kidney and bladder), a duplex collecting system, or increased bladder wall thickness raise the need for a voiding cystourethrogram (VCUG). Mild, isolated enlargement, on the other hand, is followed with ultrasound alone at most centers initially.
  • In an infant with a febrile UTI, guidelines consider children under two years a low-threshold group for VCUG; this threshold drops further if the ultrasound is abnormal, the infection was atypical or severe, or the infant is male.
03

Antibiotic prophylaxis (CAP) in infants: who, and why?

Antibiotic prophylaxis (CAP; a single nightly dose, about one-quarter to one-third of the treatment dose) is the cornerstone of reflux management in infancy; the goal is to protect the kidney from infection until the ureteral tunnel lengthens with growth.

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  • Guidelines agree on one point: in every infant under one year with reflux who has had a febrile UTI, CAP is started regardless of grade. In infants who have not had a febrile UTI but have high-grade (III–V) reflux, CAP is a “reasonable” option; this recommendation rests on the PREDICT trial (2023). In that study, in 1–5-month-old grade III–V infants — most found through antenatal kidney enlargement and not yet infected — two years of CAP reduced the first febrile infection from about 36% to 21%; no difference was shown in new scarring or kidney function, but resistant organisms increased. In other words, about one infection is prevented for every seven infants treated; this is a trade-off to weigh together with the family.
  • In infants with low-grade (I–II) reflux who have not had an infection, most centers prefer close follow-up without CAP. Drug choice varies with age: amoxicillin or a first-generation cephalosporin in newborns and young infants, trimethoprim-sulfamethoxazole after two months; nitrofurantoin is reserved for after infancy. A febrile infection occurring while on CAP means the treatment step needs to be reassessed.
04

What does circumcision offer a male infant?

Circumcision is a simple option that lowers the risk of urinary tract infection in male infants with vesicoureteral reflux, and it is mentioned for this purpose in the EAU/ESPU and AUA guidelines.

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  • Bacteria that collect under the foreskin can reach the urinary tract easily, especially in the first year; circumcision removes this source. The benefit is most evident in infants under one year with high-grade reflux. Circumcision does not correct the reflux itself, but it lowers the risk of infection — the real danger of reflux — and in some infants it can lay the groundwork for a shorter course of CAP.
  • In our practice, circumcision is presented as a medical option, with respect for the family's cultural and personal preference; it is not a mandatory step.
05

Outlook for resolution in the first year

The most encouraging aspect of vesicoureteral reflux in infants is that spontaneous resolution happens fastest in the first years of life; as the child grows, the ureter's tunnel through the bladder wall lengthens and the valve function strengthens.

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  • In the literature, cumulative resolution rates are reported at about 70–80% for grade I–II, around 50% for grade III, around 30% for grade IV, and 10–15% for grade V; these rates accumulate over years and tend to run higher in children diagnosed in infancy. In male infants, even a portion of high-grade reflux has been observed to regress within the first two years. Bilateral reflux and severe dilation lower the chance of resolution.
  • For this reason, our plan in infancy is usually a “protect and wait” approach: CAP (if needed) and close follow-up, with a comprehensive reassessment once the first year is complete. Surgical options come up in infancy only if there is recurrent febrile infection while on CAP, new scarring, or an accompanying anatomical problem. In our practice, this follow-up that begins in infancy continues, through treatment and later monitoring, in the hands of the same two pediatric urologists.
06

What should you watch for at home?

The most important part of follow-up in infancy is the family's own observation; fever is often the only sign of infection.

  • Unexplained fever of 38°C or higher, especially if it lasts more than 24 hours.
  • Poor feeding, persistent irritability, vomiting, or failure to gain weight.
  • Foul-smelling or cloudy urine, or noticeable crying during urination.
  • Fever in an infant on CAP: also tell your doctor whether a dose was missed.
  • Do not miss follow-up appointments.
  • In the situations below, ask for a urine culture without delay; the culture should be taken before antibiotics are started and with the correct method (catheter or suprapubic sample in an infant).
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Frequently asked questions
My baby has never had an infection; is antibiotic prophylaxis mandatory?
Not mandatory — it depends on the grade. For high-grade (III–V) reflux, CAP may be recommended based on the PREDICT trial; for low-grade reflux, most centers prefer close follow-up without medication. The decision is made together with the family's preference and reviewed every six to twelve months.
Can antibiotic prophylaxis harm my baby?
The dose used is low and well tolerated; the most notable downside is the development of resistant bacteria and, rarely, allergy or digestive complaints. The drug is chosen to suit the child's age; certain drugs are avoided in newborns. It is used for as long as the benefit continues, then stopped.
Is surgery needed in infancy?
Rarely. Since the chance of resolution is high in infancy, surgery is generally postponed in the first year; endoscopic injection or reimplantation is discussed only if there is recurrent febrile infection while on CAP, new scarring, or an anatomical problem.
How many months until the next imaging study?
Routine repeat VCUG is not needed for low-grade reflux; follow-up continues with ultrasound. For high-grade reflux, and before a treatment decision, most centers reassess with VCUG or radiation-free contrast-enhanced voiding urosonography (ceVUS) at 12–24 month intervals.
Next • By age and special situationsVUR in Young Children (1–5 Years): The Toilet-Training Years→
Related pagesFull index →
Diagnosis and evaluationKidney Enlargement Before Birth (Antenatal Hydronephrosis) and VURHearing the words ‘kidney enlargement’ or ‘kidney dilation’ on a pregnancy ultrasound worries families; yet most antenatal hydronephrosis is transient and resolves on its own after birth. Even so, roughly 10–20% of these infants are found to have vesicoureteral reflux (VUR). This page explains what the enlargement means and which tests are done, and when, after birth.Treatment pathwaysAntibiotic Prophylaxis (CAP) in VUR: Who Needs It, and for How Long?In the surveillance of vesicoureteral reflux (VUR), antibiotic prophylaxis (CAP, continuous antibiotic prophylaxis) is a low-dose, once-daily medication given to protect the kidney from infection. It is not needed by everyone; large studies have increasingly clarified who benefits from it. This page explains the evidence, how it is used, and the duration.Treatment pathwaysVUR and Circumcision in Baby Boys: Does It Reduce Infection Risk?Families of baby boys diagnosed with vesicoureteral reflux (VUR) often ask whether circumcision reduces the risk of infection. Guidelines answer this positively: circumcision, particularly under one year of age and in high-grade reflux, reduces the risk of urinary tract infection and is offered to families as an option. This page explains the evidence, its limits, and the special situations that require caution.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.
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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