ABSTRACT
OBJECTIVE: Therapeutic delay has been suggested as the most important factor that is likely to have an effect on the development of scarring after acute pyelonephritis. However, this opinion has not been supported by prospective studies, so we tested it. METHODS: In a prospective clinical study, we evaluated whether the time interval between the onset of the renal infection and the start of therapy correlates with the development of acute inflammatory changes and the subsequent development of renal scars, documented by dimercaptosuccinic acid scintigraphy. A total of 278 infants (153 male and 125 female) aged 0.5 to 12.0 months with their first urinary tract infection were enrolled in the study. RESULTS: The median time between the onset of infection and the institution of therapy was 2 days (range: 1-8 days). Renal inflammatory changes were documented in 57% of the infants. Renal defects were recorded in 41% of the patients treated within the first 24 hours since the onset of fever versus 75% of those treated on day 4 and onward. Renal scarring was developed in 51% of the infants with an abnormal scan in the acute phase of infection. The frequency of scarring in infants treated early and in those whose treatment was delayed did not differ, suggesting that once acute pyelonephritis has occurred, ultimate renal scarring is independent of the timing of therapy. Acute inflammatory changes and subsequent scarring were more frequent in the presence of vesicoureteral reflux, especially that which is high grade. However, the difference was not significant, which suggests that renal damage may be independent of the presence of reflux. CONCLUSIONS: Early and appropriate treatment of urinary tract infection, especially during the first 24 hours after the onset of symptoms, diminishes the likelihood of renal involvement during the acute phase of the infection but does not prevent scar formation.
