Intrarenal reflux is linked to subsequent kidney scarring: a retrospective study.

BACKGROUND

This study investigates whether intrarenal reflux (pyelotubular backflow) is associated with kidney scarring in children with urinary tract infection (UTI).

METHODS

We retrospectively reviewed 441 children diagnosed with UTI who underwent voiding cystourethrography (VCUG) and a technetium-99 m dimercaptosuccinic acid (DMSA) scan more than 3 months after the UTI. Intrarenal reflux was identified on VCUG. Using multivariable logistic regression, we analyzed the association between intrarenal reflux and kidney scarring on DMSA scans, adjusting for vesicoureteral reflux (VUR) grade and other clinical variables.

RESULTS

Out of 874 kidney units, VUR was detected in 255 units (29.1%), with intrarenal reflux present in 35 units (13.7%). Kidney scarring was observed in 12.7% of all kidney units. Intrarenal reflux was significantly associated with an increased risk of kidney scarring (odds ratio 3.35, 95% confidence interval 1.31-8.58) after adjusting for VUR grade. Notably, 92% of photon defects on DMSA scans in units with intrarenal reflux were located at the reflux site.

CONCLUSIONS

Intrarenal reflux is an independent predictor of kidney scarring beyond conventional VUR grading. Recognizing and reporting intrarenal reflux during VUR assessment may aid in developing tailored management strategies for children with UTI and VUR.