Can ultrasonography or uroflowmetry predict which children with voiding dysfunction will have recurrent urinary tract infections?

Purpose: It has been suggested that in children with voiding dysfunction improper bladder emptying contributes to recurrent urinary tract infections (UTIs) and progressive renal scarring. Incomplete bladder emptying may be related to bladder-sphincter dyssynergia. Ultrasonography and uroflowmetry are used in the initial evaluation of many children with voiding dysfunction. We determine in children with voiding dysfunction whether incomplete bladder emptying has an important role in the pathogenesis of urinary tract infections and whether abnormal ultrasonography or uroflowmetry can predict which children are at increased risk of recurrent UTIs. Materials and Methods: In this retrospective cohort study charts of 148 consecutive patients diagnosed with voiding dysfunction were reviewed for information regarding residual urine volumes on initial post-void ultrasound and the number of urinary tract infections on followup. Initial uroflowmetry curves were blindly reevaluated for this study. Results: Considerable (greater than 10% predicted) post-void residual urine volumes were seen on 15% of ultrasounds, and 78% of uroflowmetry studies were characterized as abnormal. The volume of residual urine (corrected for age) showed a positive correlation with the number of UTIs occurring after the initial visit (r = 0.3, p <0.002). There was no correlation between an abnormal uroflow pattern and number of subsequent UTIs. Conclusions: Although increased residual urine on post-void ultrasound increases the risk of UTI recurrence in children with voiding dysfunction, it does not allow accurate identification of specific children at risk.