Imaging Practices and Implications in Young Infants With Urinary Tract Infection.

OBJECTIVES: Management of infants aged ≤60 days with urinary tract infections (UTI) is challenging. We examined renal imaging in infants aged ≤60 days with UTI at a tertiary care children's hospital to identify the impact of standardizing renal ultrasound (RUS) interpretation. METHODS: We retrospectively studied infants aged ≤60 days hospitalized for UTI or fever with urine culture and renal imaging obtained and final diagnosis of UTI. RUS initially had noncriterion-based (NCB) interpretation by experienced pediatric radiologists. For this study, a single pediatric radiologist used a criterion-based (CB) hydronephrosis grading system to reinterpret films initially classified as "abnormal" on the NCB reading. We compared final renal imaging results between NCB and CB groups. RESULTS: Of 193 infants, 180 (93%) had inpatient RUS with 114 (63%) abnormal NCB interpretation. Of those with initially abnormal NCB interpretation, 85 OF 114 (75%) had minor and 29 OF 114 (25%) had significant abnormality by CB reinterpretation. In follow-up, the CB "minor abnormality" group showed 25% abnormal renal imaging, whereas the "significant abnormality" group showed 77% abnormal renal imaging with 54% having high-grade reflux on a voiding cystourethrogram (VCUG). Patients with CB inpatient RUS minor abnormality showed 3% abnormal RUS at follow-up, but 13% showed high-grade reflux on VCUG. CONCLUSIONS: Standardized RUS interpretation in young infants with UTI improved the accuracy of identification of abnormalities on follow-up renal imaging. In patients with CB minor abnormality on inpatient RUS, our results suggest limited utility of follow-up RUS; however, follow-up VCUG remained useful to identify high-grade reflux.