When should cystourethrography be performed in infants at their first urinary tract infection?

Urinary tract infection (UTI) is the most common bacterial infection in infants. It may be associated with the concomitant presence of a kidney malfunctioning picture, in particular vescicoureteral reflux (VUR). Voiding cystourethrography (VCUG) is the gold standard method to diagnose VUR but it is an invasive procedure that is not free of risk. The indication of micturating cystourethrography (MCU) in infant at the first episode of UTI does not find in the literature the unique recommendations. VUR has usually a benign prognosis and the attitude followed for its management is in most cases waiting, without any specific intervention. In fact both antibiotic prophylaxis and surgery do not substantially improve the prognosis of VUR. The likelihood of being faced with a high grade of VUR (≥ III grade) in infants at the first UTI is very high (about 50% of cases) in the presence of two risk conditions: an infection caused by non-E. Coli and a concomitant abnormality in renal ultrasound. In cases of E. coli infection and with normal renal ultrasound (which are the majority) the likelihood of finding a high grade underlying VUR is very low (1% of cases).