Evolution of scintigraphic renal lesions in children after an episode of acute pyelonephritis

Background: Abnormal Dimercaptosuccinic acid (DMSA) renal scintigraphy performed six months after an acute pyelonephritis (AP) is generally interpreted as scarring. Aim: To perform a follow up of childhood patients showing scintigraphic renal lesions during the acute phase of pyelonephritis (within 7 days from the beginning of fever). Material and Methods: A scintigraphic control was carried out at 5-7 months and, in case of persistent lesions, an additional late scintigraphy at 10-13 months. All patients were followed clinically for one year and those with a relapse of urinary tract infection were excluded from the study. Results: Eighty five patients with a median age of 8 months were included. Among these, the first scintigraphic control was normal in 59 (69%) and abnormal in 26 patients (31%). In five of these 26 patients (5/26: 19%-5/85: 6%), a considerable regression of the lesions was obvious on the early control, and normalized completely on the late control. When expressing the results in kidney units, 107 showed lesions during the acute phase of infection; 69% was normal at the early control. Thirty three showed lesions persisting at the early control (31%) and 7 out of these 33 (21%) became normal on the late control (7/107: 7%). In total, 25% of the children included in the study (24% of the kidney units) remained with renal sequelae one year after the initial episode of AP. Conclusions: The persistence of scintigraphic lesions six months after an episode of AP, does not necessarily correspond to permanent scars, since normalization can sometimes be observed on late controls. (Rev Med Chile 2012; 140: 746-750).