Prediction of Vesicoureteral Reflux in Children with First Urinary Tract Infection by Dimercaptosuccinic Acid and Ultrasonography

Objective: Urinary tract infection (UTI) is one of the most common causes of febrile pediatric diseases. Also, vesicoureteral reflux (VUR) is a significant risk factor for UTI. Voiding cystourethrography (VCUG) is the method of choice for evaluation of VUR. This study was done to predict VUR by DMSA scan (technetium 99 m-labeled dimercaptosuccinic acid) and ultrasonography (US).
Methods: In a prospective study, all children with first time acute pyelonephritis were selected and evaluated by DMSA scan and US. Then VCUG was done with negative urine culture. All children with final diagnosis of obstructive congenital anomaly were excluded. The sensitivity, specifity, positive predictive values, negative predictive values, Confidence Interval of DMSA scan and US were calculated for prediction or exclusion of VUR.
Findings: Among 100 children with UTI diagnosis, VUR was detected in 39 children and 63 (31.5%) kidneys. DMSA scan was abnormal in 103 (51.5%) units, 45 units had VUR (PPV=44%), 79 units with normal DMSA scan had no VUR (NPV=81%). Of kidney units that were abnormal by DMSA or US, 51 units had VUR. PPV and NPV were 44% and 56%, respectively.
Conclusion: DMSA scan alone or with US cannot predict VUR (especially low grade VUR). But according to NPV, it seems that absence of VUR can be predicted. So, more studies are needed to determine the usefulness of DMSA scan and US instead of VCUG for detection of VUR.