Urinary tract infection and vesicoureteral reflux
How to confirm a febrile urinary tract infection correctly, treat it effectively, and know who needs imaging and who needs a pediatric urologist.
Step 1 of 13
Objectives
After this course you will be able to
- Collect a urine sample correctly for the child's age and interpret the result.
- Recognize febrile UTI (pyelonephritis) and atypical UTI.
- Choose between oral and intravenous treatment.
- Apply the imaging algorithm after a first febrile UTI.
- Know the VUR grades and the indications for prophylaxis and surgery.
- Take into account the role of bladder and bowel dysfunction.
Key message: a UTI is diagnosed by culture of properly collected urine. A positive result from a urine bag is not a diagnosis.
Basics
UTI in numbers
- 5–7%of infants with fever without a source
- ~8% / ~2%of girls / boys by age 7
- ~80%caused by E. coli
- ~15%renal scarring after a first febrile UTI
Risk factors: uncircumcised boys in the first year of life, vesicoureteral reflux, urinary tract obstruction, bladder and bowel dysfunction (constipation), neurogenic bladder, sexual activity in adolescent girls.
Basics
Vesicoureteral reflux (VUR)
Backflow of urine from the bladder into the ureter and kidney. Primary VUR is related to immaturity of the valve mechanism where the ureter enters the bladder and often resolves with age. Secondary VUR is caused by high pressure, as in obstruction (PUV) or neurogenic bladder.
- 1–2%of the general pediatric population
- 30–40%of children with febrile UTI
- ~30%of siblings of a child with VUR
Basics
VUR grades
| Grade | Appearance on VCUG (voiding cystourethrogram) |
|---|---|
| I | Contrast reaches the ureter only |
| II | Ureter, pelvis and calyces fill, no dilation |
| III | Mild to moderate dilation of the ureter and pelvis, slight blunting of the fornices |
| IV | Moderate dilation, tortuous ureter, blunted fornices, papillary impressions preserved |
| V | Severe dilation and tortuosity, papillary impressions lost |
Low-grade (I–II) reflux resolves on its own within a few years in most children. High grade, bilateral reflux and BBD reduce the likelihood of resolution.
Diagnosis
How is a urine sample collected?
| Age | Method | Note |
|---|---|---|
| Toilet-trained child | Midstream sample after washing | The most practical method |
| Infant in diapers, stable | Clean-catch method with stimulation (for example, Quick-Wee) | Requires patience, moderate contamination |
| Infant in diapers, severely ill or a quick result needed | Catheter or suprapubic aspiration | The most reliable result |
| Any age | Urine bag | Only a negative result is reliable; a positive result must be confirmed |
Urine must be collected before the first dose of antibiotic. Even a single dose can make the culture falsely negative.
Diagnosis
Diagnostic criteria
- Urinalysis: positive leukocyte esterase and/or nitrite, pyuria or bacteriuria on microscopy.
- Culture: ≥ 50,000 CFU/ml of a single pathogen in catheter urine, ≥ 100,000 CFU/ml in a midstream sample. Any growth on suprapubic aspiration is significant.
- The diagnosis is made on urinalysis and culture together. Bacteriuria without pyuria is often asymptomatic bacteriuria or contamination.
Febrile UTI (with fever ≥ 38 °C) is regarded as infection of the renal parenchyma, that is, pyelonephritis. A UTI without fever, with only frequency and painful voiding, is usually cystitis.
Diagnosis
Atypical UTI
A UTI is considered atypical if any of the following is present: the child needs hospitalization and intravenous treatment, there is an abdominal or bladder mass and a weak stream, creatinine is elevated, there is sepsis, there is no response to an appropriate antibiotic within 48 hours, or the pathogen is not E. coli.
In atypical UTI, ultrasound is done during the acute phase and the child is referred to a pediatric urologist, because obstruction or high-grade reflux is more likely.
Diagnosis
Imaging after a first febrile UTI
- Kidney and bladder ultrasound: in infants and young children after a first febrile UTI.
- If the ultrasound is normal and the UTI is typical: VCUG is usually not needed; BBD is assessed and the family is told to have a urinalysis done with any recurrent fever.
- Dilation, scarring or a bladder abnormality on ultrasound, atypical UTI or recurrent febrile UTI: VCUG and referral to a pediatric urologist.
- DMSA to assess renal scarring: in selected cases, 4–6 months after the acute infection.
Some centers first check for renal damage with DMSA and perform VCUG only if the DMSA is abnormal (the "top-down" approach). The choice is made together with a pediatric urologist based on age, risk and local resources.
Treatment
Treatment of febrile UTI
- Intravenous initial therapy: infants younger than 2–3 months, severe illness or sepsis, vomiting and inability to take oral medication, atypical UTI.
- Oral treatment: in other children, oral treatment is as effective as intravenous.
- Duration: usually 7–10 days for febrile UTI; shorter courses are sufficient for cystitis.
- Drug choice: based on local resistance (for example, second- or third-generation cephalosporins, amoxicillin-clavulanate); adjusted according to the culture result.
Nitrofurantoin does not reach adequate concentrations in renal tissue, so it is not used for febrile UTI.
If fever persists after 48 hours despite appropriate treatment, abscess and obstruction should be ruled out with ultrasound.
Treatment
Antibiotic prophylaxis
Given once at night, at about one quarter of the treatment dose. In large randomized trials (RIVUR, PREDICT), prophylaxis reduced the risk of recurrent UTI but increased the risk of resistant bacteria.
- Greatest benefit: infants with high-grade (III–V) VUR, children with BBD, recurrent febrile UTI.
- In older children with low-grade VUR and normal bladder function, follow-up without prophylaxis is acceptable.
- BBD must be treated during prophylaxis; if constipation persists, the effect of prophylaxis is reduced.
Treatment
Indications for surgery in VUR
- Recurrent febrile UTI despite prophylaxis (breakthrough infection).
- New scars on DMSA.
- High-grade, persistent reflux that is unlikely to resolve with age.
- The family does not want, or is unable to follow, long-term prophylaxis.
| Method | Characteristics |
|---|---|
| Endoscopic injection | Short anesthesia, no incision, day surgery; success about 70–90% depending on grade |
| Ureteral reimplantation (open or robot-assisted) | Success above 95%, a larger operation |
Treatment
Long-term follow-up
- In children with renal scarring, blood pressure and proteinuria are checked regularly.
- Urinalysis with every fever: the family is told when and how to seek care.
- BBD: constipation and voiding habits are asked about at every visit.
- Girls with VUR are informed about the risk of UTI in future pregnancy.
The pediatrician's role: a proper urine sample, timely antibiotics, ultrasound after the first febrile UTI, treatment of BBD and referral of at-risk children to a pediatric urologist.
Quiz
Quiz: UTI and vesicoureteral reflux
Test yourself: choose one answer.
-
A 10-month-old girl has a fever of 39 °C, and urinalysis from a urine bag is nitrite-positive. What is the next step?
A positive bag result may be contamination. Culture of catheter urine obtained before antibiotics confirms the diagnosis.
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An 8-month-old infant has a first febrile UTI: stable, tolerating oral intake, pathogen E. coli. What is the most appropriate treatment?
In stable children older than 2–3 months, oral treatment is as effective as intravenous. Nitrofurantoin is not used for febrile UTI.
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After a first typical febrile UTI, the ultrasound is normal. Is a VCUG needed?
After a first typical febrile UTI with a normal ultrasound, VCUG is usually deferred. Recurrent febrile UTI, abnormal ultrasound and atypical UTI are indications.
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On VCUG, the ureter and pelvis are moderately dilated, the ureter is tortuous, and papillary impressions are preserved. What is the VUR grade?
Moderate dilation, a tortuous ureter and preserved papillary impressions are characteristic of grade IV. In grade V the papillary impressions are lost.
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A child with VUR has recurrent febrile UTIs while on prophylaxis. Which factor should be checked above all?
BBD (especially constipation) is one of the most important causes of breakthrough infections and should be treated before a decision on surgery.
Course completed
Related articles for parents
Sources
- Roberts KB; Subcommittee on Urinary Tract Infection. Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011;128(3):595–610.
- RIVUR Trial Investigators. Antimicrobial prophylaxis for children with vesicoureteral reflux. N Engl J Med. 2014;370(25):2367–2376.
- Morello W, Baskin E, Jankauskiene A, et al. Antibiotic prophylaxis in infants with grade III, IV, or V vesicoureteral reflux. N Engl J Med. 2023;389(11):987–997.
- Hoberman A, Wald ER, Hickey RW, et al. Oral versus initial intravenous therapy for urinary tract infections in young febrile children. Pediatrics. 1999;104(1 Pt 1):79–86.
- EAU Guidelines on Paediatric Urology, 2025: Urinary tract infections; Vesicoureteral reflux.
This material is intended for medical professionals and is based on current clinical guidelines. Decisions about an individual patient are made by the treating doctor.