Diagnostic Value Of Urine Microscopy Leukocyte Findings in Predicting Urine Culture Positivity in Routine Clinical Practice

ObjectiveUrine cultures are frequently requested at an early stage in primary care and outpatient settings, often without a comprehensive clinical assessment. This practice increases healthcare costs and laboratory workload and may lead to misleading results due to asymptomatic bacteriuria and specimen contamination. This study aimed to evaluate whether routinely reported microscopic urinary leukocyte findings can predict urine culture positivity under real-world clinical conditions. The distribution of isolated microorganisms and the frequency of mixed or contaminated growth were assessed. MethodsThis retrospective, laboratory-based diagnostic accuracy study included all urine samples sent for culture over a one-year period at a tertiary care hospital, provided concurrent microscopic urinalysis was available. No additional clinical exclusion criteria were applied to reflect the routine practice. Leukocyte findings were reported semi-quantitatively and analyzed both categorically and as approximate numerical values. The urine culture results were classified as positive, negative, or mixed/contaminated growth. The diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. ResultsA total of 8,478 urine samples were analyzed in this study. Urine culture positivity was detected in 2,666 (31.4%) samples, whereas 5, 812 (68.6%) showed no growth. Culture positivity increased significantly with higher leukocyte levels (p < 0.001), ranging from 13.1% in the lowest category to 83.1% in samples with abundant leukocytes. ROC analysis demonstrated an acceptable discriminative performance (AUC = 0.747). The Youden index identified an optimal threshold of approximately 5.5 leukocytes per high-power field, with a sensitivity of 60.4% and a specificity of 77.8%. Mixed or contaminated growth was the most common finding among culture-positive samples (43.5%), followed by Escherichia coli (29.5%). ConclusionMicroscopic urinary leukocyte findings were significantly associated with urine culture positivity and demonstrated acceptable predictive performance in real-world clinical practice settings. Although leukocyte microscopy alone is not diagnostic, it may support more selective urine culture ordering, reduce contamination, and contribute to rational diagnosis and antimicrobial management in primary care.