Objective:The 2011 American Academy of Pediatrics (AAP) guidelines address imaging after initial febrile urinary tract infection (UTI) in infants >2 months of age. We sought to determine the frequency of upper urinary tract anomalies (hydronephrosis and vesicoureteral reflux (VUR)) in hospitalized premature infants with UTI.Study design:We retrospectively reviewed the electronic medical records of neonatal intensive care unit (NICU) admissions at a tertiary care children's hospital between 1 January 2006 and 31 December 2010. We queried the records for UTI, renal ultrasound (US) and voiding cystourethrogram (VCUG).Result:We identified 3518 unique admissions. UTI occurred in 118 infants (3%). Sixty-nine (60%) had a normal US. Renal dilation was predominantly renal pelvic dilation (12%) and isolated caliectasis (22%). VUR was identified in 15 (14%) infants evaluated with a VCUG. VUR was identified in nine (12%) infants without and in seven (16%) with an abnormality on US. Reflux was identified in 7% of male and 38% of female infants with a UTI.Conclusion:Anatomic abnormalities of the upper urinary tract are uncommon in premature infants with a UTI that occurs during neonatal hospitalization. In concordance with the AAP guidelines, a VCUG may not be required in all NICU infants under age 2 months after a single UTI.