Should We Believe the Urinalysis?

In the post–Haemophilus influenzae type b, postpneumococcal immunization era, urinary tract infections (UTIs) are the most common serious bacterial infection in infants and young children. The diagnosis of UTI is challenging in this population and has received much attention, including a 2011 American Academy of Pediatrics clinical practice guideline (CPG) on diagnosis and management of UTI in febrile infants and young children.¹ The recent article by Shaikh et al² in Pediatrics on the association between uropathogens and pyuria and the accompanying commentary by Aaron Friedman³ support the importance of a urine culture even in the absence of a negative urinalysis (UA). On the other hand, Schroeder et al⁴ find that in infants <3 months with a true UTI, UA sensitivity is higher than previously reported for UTI, suggesting that the UA is reliable even in young infants. What is a clinician to do?

As Dr Lewis First suggests in his commentary, let’s look at the context.⁵ The discrepancy regarding the utility of a UA as a screening test for UTI may be due to the different populations that these studies are addressing. Shaikh et al² evaluated children with “symptoms consistent with a diagnosis of a UTI” in whom it would make sense to have a high index of suspicion even with a negative UA and perhaps have a lower threshold for starting antibiotics pending urine culture results, which always should be obtained. Such an approach may be too conservative in a well-appearing (likely not bacteremic) patient with fever without localizing source with a low suspicion of UTI (based on low assessment of UTI risk), in whom a negative urinalysis is likely to be reassuring by itself. The 2011 American Academy of Pediatrics CPG has it spot on in recommending that a negative UA may be sufficient if antibiotics are not planned in a well-appearing patient with fever without source. However, if ill-appearing and/or if antibiotics are planned, a reliable urine culture must be obtained. Finally, the CPG recommends that to establish a diagnosis of UTI, both a UA and urine culture are required. This CPG addresses a common clinical scenario in pediatrics (evaluation of the most common serious bacterial infection in children with fever), and continues to be a helpful resource for pediatric clinicians.

• Copyright © 2017 by the American Academy of Pediatrics