What is the management for a 2-year-old child with a first episode of Escherichia coli (E. coli) urinary tract infection (UTI) and mild hydronephrosis?

Management of First E. coli UTI with Mild Hydronephrosis in a 2-Year-Old

A voiding cystourethrogram (VCUG) is indicated for this child because the renal ultrasound revealed hydronephrosis, which suggests possible high-grade vesicoureteral reflux (VUR) or obstructive uropathy. 1

Immediate Management

Antibiotic Treatment

• Treat with oral antibiotics for 7-14 days using first-line agents including cephalosporins (cefixime, cefpodoxime, cefprozil, cefuroxime axetil, cephalexin) or amoxicillin-clavulanate 2
• Avoid nitrofurantoin for febrile UTIs as it does not achieve adequate serum concentrations to treat pyelonephritis 2
• Adjust therapy based on culture and sensitivity results once available 2
• Most children should show clinical improvement within 24-48 hours of starting appropriate antibiotics 2

Clinical Monitoring

• Instruct parents to seek prompt medical evaluation (ideally within 48 hours) for any future febrile illnesses to ensure recurrent infections are detected and treated promptly 1
• Early treatment limits renal damage better than late treatment, and the risk of renal scarring increases with recurrent infections 1

Imaging Algorithm

Already Completed: Renal and Bladder Ultrasound

• The ultrasound has appropriately been performed and revealed mild hydronephrosis 1

Required Next Step: VCUG

• VCUG is specifically indicated when renal and bladder ultrasound reveals hydronephrosis, scarring, or other findings suggesting either high-grade VUR or obstructive uropathy 1
• The American Academy of Pediatrics guidelines explicitly state that while routine VCUG after the first UTI is not recommended, it IS indicated if ultrasound reveals hydronephrosis 1
• The ACR Appropriateness Criteria confirm that VCUG is appropriate when ultrasound shows abnormalities 1

Rationale for VCUG in This Case

• Detection of high-grade VUR (grades III-IV) is critical because these children benefit significantly from prophylactic antibiotics 1
• Children with high-grade VUR have increased risk of recurrent UTIs and renal scarring 1
• The Swedish study demonstrated that children with dilated (grade III or IV) VUR who received prophylactic antibiotics had the lowest incidence of renal scarring (number needed to treat for 2 years was 5) 1
• Hydronephrosis on ultrasound suggests possible high-grade reflux that requires confirmation 1

Management Based on VCUG Results

If High-Grade VUR (Grades III-V) is Detected:

• Consider antimicrobial prophylaxis as the RIVUR study showed prophylactic antibiotics decreased recurrent UTI incidence by half in children with VUR (number needed to treat for 2 years was 8) 1
• Children with high-grade VUR benefit even more from prophylactic antibiotics 1
• Follow-up VCUG should be performed between 12-24 months after initial UTI, with longer intervals for lower-grade VUR 1
• Annual renal ultrasound to monitor renal growth and parenchymal scarring 1

If No VUR or Low-Grade VUR (Grades I-II):

• Continue close clinical monitoring without prophylactic antibiotics 1
• VCUG should be performed if there is a second febrile UTI 1
• Obtain urine specimen at onset of any subsequent febrile illness 1

Common Pitfalls to Avoid

• Do not skip VCUG when hydronephrosis is present on ultrasound - this is a specific indication that overrides the general recommendation against routine VCUG after first UTI 1
• Do not use ultrasound alone to screen for VUR, as it has poor sensitivity (approximately 25% detection rate) 1
• Do not treat with short courses (1-3 days) for febrile UTIs, as these are inferior to 7-14 day courses 2
• Do not use nitrofurantoin for febrile UTIs in young children 2

Long-Term Considerations

• Approximately 15% of children develop renal scarring after first UTI episode 3
• Renal scarring can lead to hypertension (5% of cases) and chronic kidney disease (3.5% of ESRD cases) 3
• The presence of hydronephrosis increases concern for underlying anatomic abnormalities that may predispose to recurrent infections and renal damage 1