Background and Aims Vesicoureteral reflux (VUR) is a risk factor for recurrent urinary tract infection (UTI) and renal scarring and the risk is correlated with VUR grade. The purpose of this study is to test the role of cystography in infants with febrile UTI when renal ultrasonography is normal.

Patients and Methods It is part of a prospective study of 383 infants less than 2 years old at the time of their febrile UTI. 297 (77.1%) had a normal renal ultrasononography (no dilatation): 106 (35%) were males and 229 (77.1%) were less than a year old. Cystography was performed 6 weeks after UTI and DMSA 6 months later. Using cystography as gold standard, a 2 × 2 table was constructed to calculate the value of cystography for the detection of renal scarring and its utility in infants with UTI who have normal ultrasonography.

Results 16 patients (5.4%) had renal scarring and six of them (37.5%) had associated reflux. VUR was present in 63 patients (21.2%). Only six (9.5%) had renal damage and 57 (90.5%) had normal DMSA (Fisher’s exact test p = 0.1). Sensitivity and specificity were 36.5% and 79.7%, respectively. The diagnostic odds ratio was 2.36 (95% CI 0.82 to 6.76) and the positive likelihood ratio 1.85 (95% CI 0.94 to 3.63). The probability of having a renal scar after a pathological cystography was only 9.5% (95% CI 4.5% to 19.3%).

Conclusions Since then, when ultrasound is normal, only 9.5% of infants with VUR had renal scar, cystography does not give additional information, then DMSA should be the next study, cystogram being a redundant imaging study.