Should we believe the Urinalysis?
Shabnam Jain, MD, MPH
In the post-HIB, post-pneumococcal immunization era, urinary tract infections (UTIs) are the most common serious bacterial infection (SBI) in infants and young children. The diagnosis of UTI is challenging in this population and has received much attention, including a 2011 AAP clinical practice guideline on diagnosis and management of UTI in febrile infants and young children.  In a recent article in Pediatrics on the association between uropathogens and pyuria, Shaikh et al found that 13% of symptomatic children whose urine was positive for a known uropathogen had absence of pyuria.  These authors and the accompanying commentary by Aaron Friedman support the importance of a urine culture even in the presence of a negative urinalysis (UA). [2,3] On the other hand, Schroeder et al in 2015 reported that in infants < 3 months with a bacteremic UTI, urinalysis has a very high sensitivity of 96-97% for UTI, higher than previously reported. They suggest that the UA is reliable even in young infants.  These two studies contradict the utility of a urinalysis as a screening test for UTI.