Accuracy of urinary symptoms and urine microscopy in diagnosing urinary tract infection in women

Background: Women with urinary tract infections (UTIs) often present with urinary complaints such as frequency of micturition, dysuria, foul-smelling urine and other non-specific symptoms like fever. Physicians may order urine microscopy to guide empirical antibiotic prescription. However, the performance of this approach has not been assessed. Objectives: This study aimed to determine the accuracy of UTI symptoms and urine microscopy associated with culture-positive UTI in Asian women. Methods: A cross-sectional study of adult women who presented with UTI-related symptoms was conducted at three public primary care clinics in Singapore. Demographic data and information on their symptoms were collected, followed by urine microscopy and culture to diagnose UTI. The sensitivity, specificity, positive (PPV), negative predictive values (NPV), accuracy (ACC) and area under curve (AUC) of combinations of symptom and urine investigations were analysed in association with culture-positive UTI, which was regarded as a benchmark. Results: Data on 564 women (73.9% Chinese, 11.5% Malay, 8.2% Indian) were analysed, of which 259 (45.9%) had culture-positive UTI. Frequency and foul-smelling urine, pyuria (WBC ≥10/hpf) and semi-quantitative bacterial count (≥2+) were significantly associated with positive urine culture. The ACC and AUC for single or multiple urinary and/or general symptoms were low. Urine pyuria (minimally >10/hpf) alone or in combination with symptoms and/or semi-quantitative bacterial count achieved high sensitivity (>85%) and PPV, NPV, ACC and AUC of >70%. Conclusion: Urinary symptoms have limited accuracy in diagnosing culture-positive UTI. Concurrent urine microscopy showing presence of pyuria and/or bacterial count increased the diagnostic accuracy of culture-positive UTI.