Investigating febrile UTI in infants: is a cystogram necessary?

Current imaging recommendations for investigating any infantile febrile urinary tract infection (UTI) are ultrasound scan (US), micturating cystourethrogram (MCUG) and dimercaptosuccinic acid (DMSA) scan. The aim of this retrospective cohort study was to determine the need and indications for MCUG in the investigation of a first febrile infantile UTI, as doubts have been raised over its benefit.Information on 427 infants who had undergone US, MCUG and DMSA following a first febrile UTI was prospectively recorded. The infants were divided into two groups: A (354) with normal renal US and B (73) with abnormal US. DMSA findings were correlated with findings on MCUG. Main outcome measures were incidence of recurrent UTIs, change in management or intervention as a result of MCUG, and outcome at discharge.Only 21/354 (6%) infants in Group A had both scarring on DMSA and vesicoureteric reflux (VUR), predominantly low-grade on MCUG. In Group B (abnormal US), 23/73 (32%) had scarring on DMSA and vesicoureteric reflux, predominantly high grade on MCUG. Of the infants with non-scarred kidneys, 73% had dilating reflux. Successful conservative treatment was performed in 423 infants, and 4 infants in Group B required surgery.We recommend US and DMSA in all infantile febrile UTI cases. Where US is normal, MCUG should be reserved for those cases with abnormal DMSA. Where US is abnormal, MCUG should be performed irrespective of findings on DMSA scan. A randomized prospective study is necessary to evaluate this further.