Renal pelvic wall thickening in childhood urinary tract infections: Evidence of acute pyelitis or vesicoureteral reflux?

Objective: The aim of this study was to determine whether renal pelvic wall thickening in active childhood urinary tract infections (UTIs), as demonstrated using ultrasound, is caused by acute pyelitis or by vesicoureteral reflux (VUR)-related chronic changes. Material and Methods: A total of 41 children with at least unilateral renal pelvic wall thickening as demonstrated using ultrasound during the acute stage of UTI, and confirmed using voiding cystourethrography (VCUG), were analyzed. All cases underwent ultrasound studies at 6 months follow-up. Results: Using ultrasound, 50 halves of the pelvis showed renal pelvic wall thickening. In 27 (54%), ipsilateral VUR could be demonstrated using VCUG. The sensitivity, specificity and positive predictive value of renal pelvic wall thickening for predicting ipsilateral VUR were 79.4%, 52.1% and 54%, respectively. Only 2 (7%) cases presented with wall thickening at 6 months follow-up. Most of the thickening recovered after clinical improvement, although VUR became persistent in half the cases. Conclusions: Renal pelvic wall thickening is an abnormal finding in the acute stage of childhood UTI and predominantly indicates acute pyelitis rather than VUR-related chronic changes. Renal pelvic wall thickening is not sufficiently predictive of VUR in acute UTI, although it does provide evidence of upper UTI.