Pyuria as a Marker of Urinary Tract Infection in Neurogenic Bladder: Is It Reliable?

Objective: The utility of the urinalysis as a potential marker to diagnose urinary tract infection (UTI) in patients with neurogenic bladder is controversial. We assessed the baseline urine characteristics and intraindividual variance of pyuria in a cohort of asymptomatic children with neurogenic bladder followed longitudinally.

Study Design: A cohort of 54 children with neurogenic bladder was followed from 2004 to 2015 at a single institution's multidisciplinary clinic. Urine data obtained from 529 routine urology visits were reviewed. Urine obtained within 2 weeks before or after treatment for UTI were excluded. Bladder surgery was defined as any operation that altered the bladder as a closed or sterile system. The effects of age, gender, catheterization, and bladder surgery on pyuria were evaluated using mixed-model regression analysis.

Results: Fifty patients with 305 urine samples had a mean length of follow-up of 3.2 years. Only 16/50 patients (32%) never had pyuria, and these patients had shorter follow-up compared with the group who ever had pyuria (≥5 white blood cells per high powered field) (1.7 vs. 3.8 years; P = 0.008). Catheterization was associated with a 15% increase in pyuria (P = 0.21). Surgery was associated with a 120% increase in pyuria (P < 0.001). The test-to-test variance of pyuria within an individual was consistently greater than between individuals (P < 0.001).

Conclusions: Bladder surgery is associated with significant increases in pyuria among children with neurogenic bladder. The substantial test-to-test variation in pyuria in asymptomatic individuals indicates the low reliability of pyuria, when positive, as a marker for UTI in neurogenic bladder and the need to search for either methods to reduce this variability or alternative biomarkers of UTI in this population.