Febrile urinary tract infection (UTI) is one of the most common bacterial illnesses in children. As febrile UTI may lead to acute renal parenchymal damage, possible permanent renal scarring, decreased renal function and endstage renal disease, early diagnosis and treatment are important. The majority (over 70-80%) of febrile UTI during childhood is known to occur in the first year of life with a male predominance . Infants are more likely to have febrile UTI than elderly due to immune system immaturity, high incidence of systemic infections, and anatomical anomalies of urinary tract . One of the reasons of male predominance in infants is high incidence of urinary tract anomalies such as vesicoureteral reflux
Children with UTI present various symptoms and signs depending on age. Generally, infants under 1 year of age have non-specific symptoms such as fever, vomiting, lethargy, poor oral in take, and diarrhea. Contrastively, children older than 5 years are known to have specific and localized symptoms and signs associated with UTI such as tenderness on cost overtebral angle, urinary frequency, dysuria, and urinary urgency, as well as fever. As the prevalence of UTI in infants under 1 year of age is high, but they usually present non-specific clinical symptoms, most of pediatricians preferen tially perform urinalysis to rule out UTI in infants with fever Additionally, for this reason, there have been vari ous reports on the clinical symptoms and early diagnosis of UTI in infants under 1 year of age. However, in the cases of older children, sometimes, the first episode of febrile UTI is difficult to diagnose. Especially, if they present gas trointestinal symptoms such as abdominal pain or vomi ting with fever, many physicians tend to underestimate the possibility of febrile UTI in comparison to the cases of in fants. As a result, performing urinalysis may be delayed.