Can a Voiding Cystourethrogram (VCUG) be performed in a patient with a Urinary Tract Infection (UTI) or should it be delayed until the infection is resolved?

Timing of VCUG in Patients with UTI

VCUG should be delayed until after the UTI has resolved and the patient has completed antibiotic treatment. 1

Rationale for Delaying VCUG

The American Academy of Pediatrics (AAP) guidelines recommend delaying voiding cystourethrography (VCUG) until after the urinary tract infection (UTI) has resolved for several important reasons:

1. Infection Resolution: Performing VCUG during an active UTI may:

   • Lead to false-positive findings of vesicoureteral reflux (VUR) due to inflammation
   • Risk spreading infection to the upper urinary tract
   • Potentially worsen the patient's clinical condition 1

2. Antibiotic Completion: Patients should complete their full course of antibiotics (7-14 days) before undergoing VCUG to ensure complete resolution of the infection 1

When to Perform VCUG

First UTI

• Not routinely recommended after first febrile UTI 1
• Only indicated if renal ultrasound reveals:
  • Hydronephrosis
  • Scarring
  • Other findings suggesting high-grade VUR or obstructive uropathy
  • Atypical or complex clinical circumstances 1

Recurrent UTI

• Recommended after recurrence of febrile UTI 1
• The risk of VUR increases significantly with recurrent infections (from 35% after first UTI to 74% with recurrent UTIs) 1

Timing Considerations

While traditionally VCUG has been recommended 3-6 weeks after UTI diagnosis, this timing should be reconsidered:

• Minimum waiting period: Complete resolution of infection and completion of antibiotics (typically 7-14 days) 1, 2
• Maximum waiting period: Should not be excessively delayed as this reduces compliance with completing the study 3, 4

Research has shown that performing VCUG within 7-10 days after UTI diagnosis (once infection has resolved) versus waiting longer:

• Does not affect detection rates or severity of VUR 3, 4
• Significantly improves the likelihood of the test being completed (100% completion when performed early vs. only 48% when delayed) 4

Important Caveats

1. Risk of iatrogenic infection: There is a small risk of causing a new UTI from catheterization during VCUG, which is why complete resolution of the initial infection is important 3

2. Radiation exposure: VCUG involves radiation exposure, so it should only be performed when clinically indicated 1

3. Patient discomfort: VCUG is an invasive and uncomfortable procedure, particularly for children, which is another reason to be judicious in its use 1

4. Recurrent UTI is not predictive: Recent research suggests that even with recurrent UTIs, the likelihood of finding abnormalities on VCUG is not significantly higher than after a first UTI 5, 6, though guidelines still recommend VCUG after recurrent infections

Algorithm for VCUG Timing

1. Diagnose and treat UTI

   • Confirm diagnosis with urine culture showing ≥50,000 CFUs/mL of a single pathogen plus pyuria 2
   • Complete full course of antibiotics (7-14 days) 1

2. Determine if VCUG is indicated

   • First UTI: Only if ultrasound shows concerning findings
   • Recurrent UTI: Recommended in most cases
   • Atypical UTI (poor response to antibiotics within 48 hours, sepsis, non-E. coli infection): Consider VCUG 1

3. Schedule VCUG

   • Optimal timing: After completion of antibiotics but within 7-10 days of diagnosis if possible 3, 4
   • Ensure patient is afebrile and asymptomatic before proceeding

By following this approach, clinicians can maximize diagnostic yield while minimizing risks to patients with suspected vesicoureteral reflux.