Background The protocol of investigations in urinary tract infection (UTI) in children mandatory includes urianalysis, uroculture, reactive C protein (RCP), blood urea (BUN), renal ultrasonography and scintigraphy. Each one of these has limits to perform in children.

Aims To establish the correlations between UTI investigations for argumentation the therapeutic decision.

Methods Retrospective study of hospitalised paediatric patients for UTI. The study parameters were: age, symptoms, RCP, BUN, uroculture, renal ultrasonography, urinanalysis (leukocytes, nitrites, pH, density, proteins, erythrocytes, ascorbic acid-AA).

Results Were studied 243 hospitalised and treated with antibiotics UTI. Uroculture was positive in 178 patients (143 E.coli, 16 Enterococcus, 17 Proteus, 2 Staphylococcus). Negative uroculture was considered as decapitated UTI by antibiotics initiated before admission. 52 patients were <1 year old. Fever has been presented in 204 patients. 96 (56,1% from patients >1 year old) presented renal specific symptoms. 22 (42,3% from patients <1 year old) presented unspecific symptoms (vomiting, diarrhoea). 84 presented high values of RCP and 25 of BUN, 104 significant leukocyturia, 12 nitrites, 211 AA, 24 abnormal ultrasonography. Fever was the most important clinical parameter in younger patients (p 0,03), while unspecific symptoms were not significantly more frequent (p 0,25); the majority of patients with high BUN also presented abnormal ultrasonography (p 0,002); the reduced frequency of nitrites was due to AA (p 0,0001). Negative uroculture has no diagnostic significance (p 0,78), only in presence of significant leukocyturia and high RCP.

Conclusions In guideline of UTI diagnosis with negative uroculture, fever, RCP, BUN, leukocyturia, ultrasonography become mandatory.