Introduction: Most authors would agree that renal parenchymal defects (scars, hypoplasia, dysplasia) in children are a major risk factor for chronic renal failure, and for development of systemic hypertension in later years. The pathophysiologic changes in acute pyelonephritis include tubulointerstitial inflammation/pus with impairment of the renal microcirculation due to compression of the glomeruli, small peritubular capillaries and vasa recta by interstitial edema. The resulting ischemia has been postulated as one of the mechanisms for the decreased accumulation of DMSA in the areas of pyelonephritis. DMSA scanning has a sensitivity of up to 99%, and specificity of up to 91% for the detection of acute pyelonephritis.
Aim of the study: The aim of the study was to investigate the value of Tc99m-DMSA scan in children with acute urinary tract infection, to estimate the degree of parenchymal changes, and to assess the relationship with vesicoureteral reflux.
Patients: We reviewed 116 infants aged 0-15 years, 100 (86.2%) female and 16 (13.8%) male, who were hospitalized for urinary tract infection during a 5-year period (1996-2000). The mean age at diagnosis was 3.7 years.
Results: Escherichia colli was isolated in 52 (44.8%) urine cultures. All patients underwent ultrasonography, which was normal in 57 (49.1%) infants. Tc99m-DMSA was performed after two weeks of therapy. The renal parenchymal pathology was defined as a focal or multifocal defect of low degree in 33 (28.4%), and of high degree in 35 (30%) children. Multifocal defects were mostly found in patients aged < 3 years, and focal lesions in those aged > 3 years. Renal scars were detected in 41 (35.3%) infants with first urinary tract infection.
Conclusion: We recommend that ultrasound, DMSA and radionuclide cystouretherogram be routinely performed in case of first urinary tract infection in infants aged < 1 year, and voiding cystourethrogram with US and DMSA in those aged > 1 year.