METHODS: Retrospective study, including patients aged less than 2 years diagnosed with UTI in the Emergency Department between July 2013 and December 2014. Patients with an underlying nephro-urological pathology, previous UTIs and those without prenatal or post-infection renal ultrasound were excluded. Altered renal ultrasound was defined as the presence of dilated urinary tract or structural abnormalities. Potential RF analysed were: male, age less than 3 months, presence of fever and microorganism other than Escherichia coli. Univariate and multivariate logistic regression were performed.
RESULTS: A total of 306 patients were included. Altered renal ultrasound was found in 35 cases (11.4%; 95% CI 8.3-15.5): 24 (68.6%) urinary tract dilation, and 11 (31%) structural abnormalities. Among the cases with altered ultrasound, 68.6% were male, 51.4% were younger than 3 months, 74.3% were febrile, and 31.4% were caused by microorganisms other than E. coli, compared to 45% (P=.009), 31.7% (P=.021), 78.2% (P=.597) and 10% (P=.001) of cases with normal ultrasound. In the multivariate analysis, age less than 3 months (OR 2.1; 95% CI 1.0-4.3, P=.05) and microorganism other than E. coli (OR 3.8; 95% CI 1.7-8.7, P=.002) remained as RF.
CONCLUSIONS: The yield of renal ultrasound after the first UTI is low. Its indication should be individualised according to the presence of RF: age less than 3 months and microorganism other than E. coli.