Multi-institutional Study Comparing the Height of Contrast During Performance of Voiding Cystourethrogram in Children

Objective To assess the effect of contrast height during the voiding cystourethrogram (VCUG). The VCUG is the gold standard diagnostic test for vesicoureteral reflux (VUR). Variation in parameters may affect detection and grade of reflux. Materials and Methods In a multicenter, prospective, nonrandomized, observational study, patients undergoing VCUG were selected. VCUG was performed per study protocol except for a change in contrast height. The initial fill was performed at 50 cm and the second at 100 cm. Data collected included presence and grade of VUR and volume filled. The actual bladder volume filled was normalized to the estimated bladder capacity (EBC) as a percentage. A Cohen's kappa coefficient of agreement was used to test for difference in the incidence of reflux and grade between contrast heights. A Wilcoxon signed-rank test was used for differences in the percent EBC filled between heights. Results From May 2012 to November 2013, 184 patients were enrolled. Seventy-one patients (39%) exhibited VUR at 50 cm and 80 patients (43%) at 100 cm. The kappa coefficient of agreement between 50 cm and 100 cm showed substantial agreement, with no significant difference in VUR grade. The percent of EBC filled at each height was significantly different: %EBC filled at 50 cm: 101 ± 46 (range 9.2-228.3), and %EBC filled at 100 cm: 130 ± 56 (range 37.8-280.6) ( P