[Pyelonephritic scar formation].

Pyelonephritic scars almost never develop after urinary tract infections alone, but require certain risk factors in addition. The most important risk factors are: vesicoureteral reflux, intrarenal reflux, obstructive uropathy, and nephrolithiasis. Most pyelonephritic scars develop in early childhood with the combination of vesico-ureteral reflux, intrarenal reflux, and urinary tract infections. Urinary tract infections alone almost never result in pyelonephritic scars. After the age of 3 years the risk developing pyelonephritic scars is not more than 10% in those with the combination of urinary tract infections and vesicoureteral reflux. In this age group the risk developing pyelonephritic scars is not altered by antireflux operation.