The Significance of (99m)Technetium Dimercaptosuccinic Acid(DMSA) Scan as a Substitute for Voiding Cystourethrography(VCUG) in Evaluating Children with first Febrile Urinary Tract Infection

PURPOSE: We studied the value of clinical signs, laboratory findings and (99m)technetium dimercaptosuccinic acid(DMSA) scan in predicting the presence of vesicoureteral reflux(VUR) in children with first febrile urinary tract infection(UTI). METHODS: A retrospective analysis of 84 hospitalized children with first febrile UTI was performed. They underwent DMSA scan and voiding cystourethrography(VCUG) during the acute phase, and were divided into three groups according to the results of the VCUG: absence of VUR, mild(grade I-II) and severe VUR(grade III-V). We studied the relation of VUR to age, gender, fever duration, causative organism, white blood cell count, serum C-reactive protein and result of DMSA scan. RESULTS: Among 84 patients, 6 had mild and 17 had severe VUR. Thirty-eight had abnormal DMSA scan. results Patients with VUR were older than those without VUR(P<0.01). There was a lower probability of infection with Escherichia coli in patients with severe VUR than in those with mild and absent VUR(P<0.01). An abnormal DMSA scan correlated with the presence and severity of VUR(P<0.05). Severe VUR was present in 10.9% of patients with normal DMSA scan. The sensitivity, specificity, positive and negative predictive values of the DMSA scan in predicting the presence of VUR were 69.6%, 63.9%, 42.1%, and 84.8%, respectively. CONCLUSION: An abnormal DMSA scan correlated to the presence and severity of VUR, but the sensitivity, specificity and positive predictive value of the DMSA scan were low. Therefore, patient with an abnormal DMSA scan requires a VCUG. In order to prevent missing the 10.9% of patients with severe VUR but normal DMSA scans, a VCUG should be performed in patient with normal DMSA scan.

Vesicoureteral Reflux and Renal Scar

PURPOSE: Vesicoureteral reflux(VUR) is the major risk factor of urinary tract infection(UTI) in children and may result in serious complications such as renal scarring and chronic renal failure. The purpose of this study was to evaluate the relationship between VUR and renal scar formation, the usefulness and correlation of various imaging studies in reflux nephropathy, and the spontaneous resolution of VUR. METHODS: We retrospectively reviewed 106 patients with VUR with no accompanying urogenital anomalies in the Department of Pediatrics, Bundang CHA Hospital during the period from Jan. 1996 to Mar. 2005. Ultrasonography and 99mTc-dimercaptosuccinic acid(DMSA) scan were performed in the acute period of UTI. Voiding cystourethrography(VCUG) was performed 1 to 3 weeks after treatment with UTI. Follow-up DMSA scan was performed 4 to 6 months after treatment and a follow-up VCUG was performed every 12 months. RESULTS: The mean age at detection of VUR was 13.8+/-22.2 months and the male to female ratio was 2:1. The incidence of renal scarring showed a tendency of direct correlation between severity of VUR(P<0.001) and abnormal findings of renal ultrasonography(P<0.01). 63.2%(24 of 38 renal units) of renal parenchymal defects present in the first DMSA scan disappeared on follow-up DMSA scans. Follow-up DMSA scans detected renal scars in 7(14%) of 50 renal units with ultrasonographically normal kidneys. Meanwhile, ultrasonography did not show parenchymal defects in 7(36.8%) of 19 renal units where renal scarring was demonstrated on a follow-up DMSA scan. The spontaneous resolution rate of VUR was higher(75%) in cases with low grade(I to III) VUR(P<0.01). CONCLUSIONS: The presence and severity of VUR and abnormal findings of renal ultrasonography significantly correlated with renal scar formation. DMSA scan was useful in the diagnosis of renal defects. Meanwhile renal ultrasonography was an inadequate method for evaluating renal parenchymal damage. Therefore, follow-up DMSA scans should be performed to detect renal scars even in children with low-grade VUR and normal renal ultrasonography.