Accuracy of standard urinalysis in predicting culture results.

Single and multiple test combinations were studied to determine the accuracy of the standard urinalysis method in predicting sterile or contaminated cultures and cultures with significant bacteriuria from gram negative rods (GNR). The results demonstrated a significant incidence of microscopic bacteriuria and pyuria in GNR culture (P < .001) and an association between large numbers of epithelial cells and culture contamination. A discriminate analysis of multiple test combinations was done to identify the order in which urinalysis tests significantly improved the ability to discriminate between culture groups. Results indicated that multiple test combinations were more predictive than single tests. Based on study results, a cost-effective scheme for ordering urine cultures is proposed.