Pyuria is often used as an import marker in the diagnosis of urinary tract infection. The interpretation of pyuria may be especially important in patients with nonspecific complaints. There is a paucity of data to demonstrate the utility of pyuria alone in the diagnosis of bacteriuria or urinary tract infection. This study aims to further define the relationship of pyuria and positive bacterial growth in urine culture, as well as the diagnostic utility of different urine white blood cell cutoff points.

A total of 46,127 patients older than the age of 18 were selected from the inpatient population of HCA Healthcare System Capital Division. Urine microscopy results were stratified by white blood cell count and correlated with positivity of urine culture bacterial growth. The optimal urine white blood cell cutoff was derived based on the receiver operating characteristic curve plot.

Urine microscopy finding of white blood cell 0-5 cell/hpf, 5-10 cell/hpf, 10-25 cell/hpf, and higher than 25 cell/hpf was associated with 25.4%, 28.2%, 33%, and 53.8% rates of bacteriuria, respectively. The receiver operating characteristic curve plot demonstrated that pyuria alone did not provide adequate diagnostic accuracy to predict bacteriuria. The optimal cutoff point for the best combination of sensitivity and specificity was found to be 25 cell/hpf.

Pyuria alone provides inadequate diagnostic accuracy for predicting bacteriuria. Urine white blood cell count greater than 25 cell/hpf was found to be the optimal cutoff to detect bacteriuria. The result of this study supports the current guideline recommendation against antibiotic treatment based on urine analysis alone. It also informs future design of randomized controlled trial that investigates interventional strategies for patients with pyuria and nonspecific complaints.