How accurate is a dipstick test for UTI in febrile infants under 12 months?

For febrile infants under 12 months, diagnosing a urinary tract infection (UTI) is challenging because symptoms are nonspecific. A dipstick test checks for leukocyte esterase (a sign of white blood cells) and nitrites (a sign of bacteria). Overall, the dipstick is good at confirming a UTI when positive, but a negative result does not completely rule out infection. The accuracy depends on the infant's age and which dipstick markers are used.

What the research says

A 2025 study in febrile infants aged 2-6 months found that a positive dipstick (≥1+ leukocyte esterase or positive nitrite) had a sensitivity of 90.2% and specificity of 89.2% for UTI, compared to urine culture ⁸. This means the dipstick correctly identified 90% of infants with UTI and correctly ruled out UTI in 89% of those without it. Another study in infants under 90 days reported a sensitivity of 86% and specificity of 80% for clean-catch samples ⁹. For infants 0-3 months, a retrospective study found that leukocyte esterase alone had 60% sensitivity and 94% specificity, while nitrites alone had 25% sensitivity and 99% specificity ⁵. In the 4-12 month group, leukocyte esterase sensitivity was 71% and specificity 91% ⁵. Combining both markers improved sensitivity but lowered specificity. Overall, dipstick is more reliable for ruling in UTI (high specificity) than ruling it out (moderate sensitivity).

What to ask your doctor

• What is the chance that my infant's dipstick result could be a false negative or false positive?
• If the dipstick is negative but my baby still has fever, should we do a urine culture?
• How does the method of urine collection (clean-catch vs. catheter) affect the accuracy of the dipstick?
• Are there any other tests, like urine microscopy, that might be more accurate for my infant?
• Should we repeat the dipstick or culture if symptoms persist?