Wettergren et al (1990) | Unselected population of 50 patients (14 girls) under 1 year of age with bacteriuria on screening, verified by suprapubic aspiration and untreated. Follow up for up to 6 years | Prospective cohort (level 4) | 1. Subsequent periodical urine cultures during the follow up period 2. Measurement of renal parenchymal thickness and renal surface area on IVU at 3 years | 1. Two infants developed pyelonephritis within 2 weeks of diagnosis of ABU. ABU recurred in 10 children* 2. No child (0/36) developed new renal damage. IR = 0 (95% CI = 0 to 0.09)* | Unselected population of well infants (not after acute UTI) Screening of bacteriuria primarily detected innocent bacteriuria and was not recommended. |
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Randolph et al (1975) | 25 girls under 6 months of age with bacteriuria, followed up with cultures up to 6 years of age. No chemoprophylaxis but treatment of individual episodes | Prospective cohort (level 4) | Development of UTI and renal scarring (IVU) during the follow up period | 1. Although described as ABU, initial episodes were always symptomatic (lower tract symptoms). No scars on initial IVU 2. Recurrences in 9 infants, always aymptomatic (lower tract symptoms) 3. New scarring developed in 3 children, all of whom had recurrences (symptomatic) and evidence of reflux, bladder trabeculation and urethral stricture. No recurrences after 3 years of age and no new scars at 6 years | Study exclusively in girls, natural history in boys may be different Even in ABU, signs of lower UTI were evident to the “instructed parents” |