Background. Urinary tract infection (UTI) is a common disease. Controversy exists about the role of radiological evaluation in the patient with urinary tract infection. Materials and Methods. From 04 2001 to 12 2001, patients with febrile UTI admitted to Chang Gung Memorial Hospital, Chiayi were prospectively evaluated by ultrasonography. The inclusion criteria of febrile UTI was a body temperature of more than 38°C with a bacterial count of 103 or more per mL in a freshly voided midstream or catheterized urine. Results. A total of 94 patients were evaluated and all patients recovered. Major abnormal sonograms were present in 17 (18%) of the patients. A history of urolithiasis and a duration of fever ≥ 3 days after admission were statistically significant clinical parameters in predicting major abnormal sonogram. Although diabetes mellitus was not statistically significant in predicting major abnormal sonogram, diabetic patients had 2.5 times the likelihood of major structural abnormalities than nondiabetic patients. Conclusion. Ultrasonographic study of patients with febrile UTI should be limited only to those with a duration of fever ≥ 3 days and a history of urolithiasis. Ultrasonographic study should also be considered in febrile UTI patients with diabetes mellitus
