Pediatric UTI

Key considerations: Pyelonephritis with bacteremia in young infants, Underlying urological abnormality (VUR, posterior urethral valves), Missed diagnosis causing renal scarring

Cannot miss

Pyelonephritis with bacteremia in young infants
Underlying urological abnormality (VUR, posterior urethral valves)
Missed diagnosis causing renal scarring

Likely diagnoses

Uncomplicated lower UTI
Pyelonephritis
Vesicoureteral reflux-related UTI
Posterior urethral valves (infant males)

Red flags

Age <2 months (sepsis risk)
Fever >39C in infant <24 months without source
Ill-appearing child
Failure to respond to antibiotics at 48 hours
Recurrent UTIs

Workup

history: Fever, irritability, vomiting, poor feeding (infants), dysuria/frequency (older children), prior UTIs, toilet training status; exam: Fever, suprapubic tenderness, CVA tenderness, abdominal exam, genitourinary exam; labs: UA (pyuria >=5 WBC/hpf, positive nitrites/LE); Urine culture (catheterization in <3 years — clean catch unreliable); Do NOT treat based on UA alone — culture required; imaging: Renal ultrasound for first febrile UTI in all children; VCUG if renal ultrasound abnormal or recurrent UTIs; bedside: Temperature, urine dipstick

Management

immediate: <2 months: IV ampicillin + gentamicin, admit; general: 2-24 months: oral cephalosporin (cefixime or cephalexin) if well-appearing, 7-14 days; Pyelonephritis: IV ceftriaxone if ill-appearing or cannot tolerate oral, step down when improving; TMP-SMX if local susceptibility allows (check antibiogram for E. coli resistance); Treat constipation (major modifiable risk factor for recurrent UTIs)

Disposition

admit: Age <2 months, ill-appearing, vomiting preventing oral meds, no improvement at 48 hours; discharge: Well-appearing child tolerating oral antibiotics with reliable follow-up; consults: Pediatric urology if abnormal RBUS or recurrent UTIs, nephrology if renal scarring

Clinical pearls

Circumcision reduces UTI risk in males by 10-fold in the first year of life
Constipation is a major modifiable risk factor for recurrent UTIs in children — always ask and treat
Clean catch urine is unreliable in children <3 years — catheterized specimen required for accurate culture

Source and review

AAP UTI Guidelines 2016. Last reviewed: 2024-11-01