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Key Features

Essentials of Diagnosis

  • Signs in newborns and infants are nonspecific

  • Abdominal or flank pain, vomiting, fever, urinary frequency, dysuria, urgency, or enuresis in preschool children

  • Classic signs of cystitis or pyelonephritis in school-aged children

General Considerations

  • An estimated that 8% of girls and 2% of boys acquire urinary tract infections (UTIs) in childhood

  • Girls older than age 6 months have UTIs far more commonly than boys, whereas uncircumcised boys younger than 3 months have more UTIs than girls

  • Circumcision reduces the risk of UTI

  • The organisms most commonly responsible for UTI are

    • Escherichia coli (> 85%)

    • Klebsiella

    • Proteus

    • Other gram-negative bacteria

    • Enterococcus or coagulase-negative staphylococci (less commonly)

  • Vesicoureteral reflux (VUR)

    • A congenital abnormality present in about 1% of the population beyond infancy

    • Detected in 30–50% of children who have a UTI at 1 year of age or younger

    • Graded using the international scale

      • I—reflux into ureter

      • II—reflux to the kidneys

      • III—reflux to kidneys with dilation of ureter only

      • IV—reflux with dilation of ureter and mild blunting of renal calyces

      • V—reflux with dilation of ureter and blunting of renal calyces

    • The natural history of reflux is to improve, and 80% of reflux of grades I, II, or III resolve or significantly improve within 3 years of detection

Clinical Findings

Symptoms and Signs

  • Newborns and infants have nonspecific signs, including

    • Fever

    • Hypothermia

    • Jaundice

    • Poor feeding, vomiting, failure to thrive

    • Irritability

    • Sepsis

    • Strong, foul-smelling, or cloudy urine may be noted

  • Preschool children may have

    • Abdominal or flank pain

    • Vomiting

    • Fever

    • Urinary frequency, urgency

    • Dysuria

    • Enuresis

  • School-aged children commonly have

    • Frequency, dysuria, and urgency (classic signs of cystitis)

    • Fever, vomiting, and flank pain (classic signs of pyelonephritis)

    • Costovertebral tenderness

  • Urethritis, poor perineal hygiene, herpes simplex virus, or other genitourinary infections may be apparent on examination


Laboratory Findings

  • Screening urinalysis

    • Indicates pyuria (> 5 WBCs/hpf) in most children

    • However, some children can have sterile pyuria without UTI

  • Nitrite tests

    • Detection of urinary nitrite by dipstick is highly correlated with enteric organisms being cultured from urine

    • However, most young children (70%) with UTI have negative nitrite tests

  • Urine culture

    • Gold standard for diagnosis

    • Proper collection of specimen is difficult in children due to frequent contamination of sample

    • Quantitative recovery of 105 cfu/mL or greater is considered significant from clean-catch specimens, and 104–105 is considered significant from catheterized specimens

    • Usually the recovery of multiple organisms indicates contamination

  • Asymptomatic bacteriuria

    • Seen commonly in children requiring chronic bladder catheterization

    • Represents colonization of the urinary tract with nonuropathogenic bacteria

    • Treatment in such cases may increase the risk of symptomatic UTI by eliminating nonpathogenic colonization

    • Screening urine cultures in asymptomatic children are, therefore, generally discouraged


  • Renal ultrasound

    • Recommended because it ...

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