RESUMEN
PURPOSE: To test the hypothesis that the diagnostic yield of cyclic cystography is related to the prevalence of vesicoureteral reflux (VUR) in the population being evaluated. MATERIALS AND METHODS: Two groups of children were examined prospectively: 124 with severe urinary tract infection, defined as patient hospitalization or a maximum temperature greater than 39.5 degrees C, and 135 with previously diagnosed VUR. Nuclear cystography was performed in 249 patients, and fluoroscopic cystography was performed in 10. If VUR was not seen during the first cycle of bladder filling and voiding, a second cycle was performed. RESULTS: VUR was present during cycle 1 in 40 (32%) of 124 patients with severe urinary tract infection and 90 (67%) of 135 children in the VUR follow-up group (P < .001). VUR was demonstrated during cycle 2 in seven (9%) of 76 of the severe urinary tract infection group and eight (24%) of 34 of the VUR follow-up group (P = .045). Of 15 patients with VUR during cycle 2, two had grade III VUR and 13 had grade I or II VUR. CONCLUSION: The second cycle of cyclic cystography has a higher diagnostic yield in patients undergoing VUR follow-up than in patients with severe urinary tract infection. The decision to perform a second cycle of bladder filling and voiding should take into account the pretest probability of VUR in the child being examined.