New research suggests that performing renal ultrasounds too quickly on hospitalized infants with a febrile urinary tract infection (fUTI) may do more harm than good. A study published in Hospital Pediatrics indicates that imaging performed within the first 24 hours often detects temporary inflammation, leading to unnecessary follow-up testing.
The “Rush” to Image May Be Misleading
When an infant is hospitalized for their first febrile UTI, guidelines often recommend a renal and bladder ultrasound (RBUS) to check for anatomical abnormalities. However, the timing of this scan is critical.
Researchers led by Dr. Melanie C. Marsh (Advocate Children’s Hospital) analyzed data from 294 infants aged 2 to 24 months. They compared results between two groups:
- Early Group: Scanned <24 hours after admission.
- Late Group: Scanned >24 hours after admission.
Key Study Findings
The data revealed that “Early” scans were significantly more likely to show abnormalities that might just be temporary reactions to the infection, rather than permanent structural issues.
- False Positives: 64.4% of early scans showed abnormalities, compared to only 40.7% of late scans.
- Uroepithelial Thickening: This specific sign of inflammation was found in 18.6% of early scans but only 4.9% of late scans.
Why This Matters for Sonographers
When an ultrasound comes back “abnormal,” it often triggers a more invasive test called a VCUG (voiding cystourethrogram) to check for reflux.
The study showed that many infants in the “Early” group underwent VCUGs that turned out to be normal. By waiting just 24 hours—allowing the initial inflammation to settle—clinicians might avoid triggering these stressful, invasive, and expensive follow-up tests.
Clinical Takeaway
While families naturally want answers quickly, Dr. Marsh notes that “a short delay in imaging may help avoid unnecessary testing while still ensuring children receive safe, appropriate care.”
For sonographers and clinicians, this suggests that waiting for the acute phase of the fever to pass may yield clearer, more accurate images using your pediatric ultrasound systems.
Source: Timing of Renal and Bladder Ultrasound After First Febrile Urinary Tract Infection: A Hospitalist Dilemma (Hospital Pediatrics, Feb 2026).