Urinary tract infection (UTI) is a common and important clinical problem in infants and young children. UTI is often suspected on the basis of results of microscopic urinalysis; accordingly, it is important that its results be as reproducible, accurate, and easily interpretable as possible. A positive urinalysis allows early detection and treatment of UTI, while a negative urinalysis can potentially eliminate the cost of expensive hospitalization for intravenous administration of antibiotics, the current standard treatment of UTI in young febrile children. In pediatric primary care facilities, microscopic urinalysis often is performed using centrifuged urine and reported as the number of white blood cells (WBCs) or bacteria per high-power microscopic field (hpf).