Initial tests (all patients): |
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Urine dipstick or microscopic urinalysis positive:Δ |
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Any elevated inflammatory marker:§ |
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ANC: absolute neutrophil count; CBC: complete blood count; CSF: cerebrospinal fluid; HPF: high-powered field; HSV: herpes simplex virus; IBI: invasive bacterial illness; PCR: polymerase chain reaction; WBCs: white blood cells.
* If procalcitonin testing is rapidly available (ie, within 1 to 2 hours), then C-reactive protein testing is optional. If procalcitonin testing is not available, then CRP should be obtained and considered along with ANC and rectal temperature in determining risk of IBI.
¶ Urine specimens obtained by bladder catheterization or suprapubic aspiration are preferred for urinalysis. Specimens obtained by bag, spontaneous voiding, or stimulated voiding are acceptable for urine dipstick testing and microscopic urinalysis but should not be sent for urine culture because of high contamination rates. Refer to UpToDate topics on urine collection techniques in infants and children.
Δ Positive results consist of any leukocyte esterase present, >5 WBCs/HPF (centrifuged urine), or >10 WBCs/HPF (uncentrifuged urine).
◊ Urine culture should be obtained by bladder catheterization or suprapubic aspiration. The American Academy of Pediatrics Clinical Practice Guideline for evaluation and management of well-appearing febrile infants 8 to 60 days old recommends that a urine culture only be sent if a urine dipstick or microscopic urinalysis is positive. However, it is reasonable to send the urine culture on all well-appearing febrile infants 8 to 60 days of age in settings with documented low rates of specimen contamination and timely urine specimen processing.
§ Inflammatory marker threshold values demonstrating high sensitivity for IBI in febrile infants include:¥ HSV studies are indicated for well-appearing infant at high risk, including those with a history of maternal active genital lesions at birth, CSF pleocytosis, or other signs of HSV infection; additional blood studies and microbiology skin and blood specimens are also required. Refer to UpToDate topics on diagnosis of HSV infection in infants.