['The 2011 American Academy of Pediatrics clinical practice guideline for childhood febrile urinary tract infection recommends voiding cystourethrography if renal and bladder ultrasound reveals hydronephrosis, scarring or "other findings" that suggest high grade vesicoureteral reflux. We sought to determine if the finding of uroepithelial thickening indicates greater risk of high grade vesicoureteral reflux and whether uroepithelial thickening improves the screening value of renal and bladder ultrasound.', 'We retrospectively analyzed renal and bladder ultrasound and voiding cystourethrogram findings in children 2 to 24 months old with first febrile urinary tract infection during an 11-year period. Patients with uroepithelial thickening were compared to an age and gender matched sample without uroepithelial thickening. Logistic regression was used to identify factors associated with high grade vesicoureteral reflux. Test characteristics of renal and bladder ultrasound for high grade reflux were compared based on different criteria to define an abnormal renal and bladder ultrasound.', 'Of 226 patients 143 (63%) had vesicoureteral reflux, of whom 37 (26%) had high grade reflux. On multivariable analysis uroepithelial thickening was a significant independent predictor of high grade vesicoureteral reflux (OR 5.41, 95% CI 1.74-16.79, p = 0.004). When hydronephrosis and hydroureter were considered the only abnormal renal and bladder ultrasound findings warranting voiding cystourethrography, sensitivity of renal and bladder ultrasound for high grade reflux was 84%, and 6 children with high grade and 82 with low grade reflux would have been missed. When uroepithelial thickening was also considered an abnormal finding, the sensitivity increased to 97%, and only 1 child with high grade and 57 with low grade reflux would have been missed.'] Does uroepithelial Thickening on Sonography improve Detection of Vesicoureteral Reflux in Children with First Febrile Urinary Tract Infection?