5-Year Prospective Results of DMSA Renal Imaging in Children with Febrile Urinary Tract Infection: The Top-Down Approach
Daniel B. Herz, M.D., Paul A. Merguerian, MD, Leslie McQuiston, MD, Mary Gheen, ARNP, Christine Danielson, ARNP.
Children's Hospital at Dartmouth / Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA.
BACKGROUND: Evaluation of children after febrile UTI involves VCUG because of the traditional association with Vesicoureteral Reflux (VUR) and renal scarring. Emphasis is placed on the presence of VUR and less on true renal risk. We submit that early DMSA renal scan after febrile UTI (Top-down approach) can predict clinically significant (cs) VUR and therefore who should get VCUG. The criticism of the top-down approach is that over time some VUR and preventable renal damage would be missed. This study was designed to validate the top-down approach.
METHODS: Over 36 months from 2001 to 2004 a prospective series of children with acute febrile UTI were studied with an initial DMSA renal scan. VCUG was obtained after/during treatment. Children with anatomic or neurological GU abnormality were excluded. UTI was treated following standard AAP guidelines. DMSA scan was repeated at 6 months if initially abnormal. Prophylactic antibiotics were used in all for 6 months (initial study phase), and thereafter only for VUR or recurrent UTI. In toilet trained (tt) children dysfunctional elimination was investigated and treated using standard diagnostic and treatment regimens. Follow-up was every 3 months in first year and every 6 months thereafter. Follow-up for all children was at least 5 years. Results of VCUG and DMSA scans were recorded and compared according to highest grade of VUR per child.
RESULTS: 121 children fit inclusion criteria and completed the study. Ages were 2 months to 11 years (mean = 3.2 years). Male to female ratio was 2:3. Overall, 88 (73%) of initial DMSA scans were abnormal, and 70(58%) had VUR. The odds ratio (OR) of VUR predicted by initially abnormal DMSA was 3.03 (95%CI+/-0.8). Abnormal follow-up DMSA scan (cortical scar) was not predictive of VUR with OR of 0.77 (95%CI+/-1.08). Abnormal initial DMSA scan predicted the presence of csVUR with OR of 4.24 (95% CI+/-0.14), and exclude csVUR with 87% NPV. Recurrent (breakthrough) UTI occurred in 19(16%) and abnormal DMSA scan was present in18 (95%). No child with a normal initial DMSA scan after febrile UTI had csVUR.
CONCLUSIONS: DMSA scan can predict clinically significant VUR and those children at greatest renal risk in the presence or absence of VUR. Initial normal DMSA excludes csVUR. Therefore, DMSA scan should be performed in all children after febrile UTI and VCUG should only be obtained in children with abnormal DMSA scan or in children with recurrent UTI since they are at greatest renal risk.