During the past decade, many paediatric societies have recommended that all young children undergo a cystography after a first febrile urinary tract infection (UTI). This systematic strategy offered a 100% sensitivity, but without any specificity, meaning that many children underwent an unnecessary cystography, a painful, irradiating and expensive examination. Regarding the recent publications minimising the clinical consequences of low-grade vesicoureteral reflux (VUR), the low rate of high-grade VUR and the current discussions on high-grade VUR treatment, new guidelines propose never to perform a cystography with the risk of recurring UTI and renal scarring. Between both these ends, an evidence-based strategy would find a place to predict high-grade VUR to avoid unnecessary cystography because cystographies miss the least number of patients with high-grade VUR. Procalcitonin has been found and validated to be a strong and sensitive predictor of VUR and especially high-grade VUR in single-centre then multicentre studies (Pediatrics 2005; J Pediatr 2007). The high sensitivity of procalcitonin was then confirmed in children with a DMSA scan-confirmed acute pyelonephritis. However, prediction tools should take into account that clinicians should probably not be ready to make their decision only on a single newly identified biological marker. We recently found performing a systematic review and meta-analysis that ureteral dilation seemed the best renal ultrasound criterion to predict both all-grade and high-grade VUR with a high specificity but a low sensitivity. Therefore, combining such a renal ultrasound criterion with procalcitonin in a clinical decision rule predicting high-grade VUR could be clinically relevant and will be presented.