Aims To compare the results of urine microscopy and urine culture using real time videos of the specimens as a refereeing traceable standard for concordance-discordance testing.
Methods Urine samples sent to be cultured were examined using phase contrast microscopy (PCM). Samples were videotaped in real time during during the microscopy process. The PCM examinations were immediately coded as positive, negative or indeterminate based on the recognition of microorganisms in the specimens. Urine culture reports were obtained. A comparison was made between PCM interpretations and culture reports. Statistical analysis was performed using urine culture reports as gold standard.
Videos of the microscoped samples were examined and classified as positive or negative based on the presence or absence of microorganisms. Concordance-discordance testing was performed comparing the video images now used as a traceable referee, separately against PCM interpretations and culture report for each sample reported. Statistical analysis was then re-performed. A comparison was made between the performance of PCM and urine cultures.
Conclusion PCM has high statistical significance when compared with urine cultures. Using traceable video clips the urine cultures were shown to be an ‘imperfect gold’.
Phase contrast microscopy showed better statistical significance (sensitivity and negative predictive value) than urine cultures when both of these methods were individually compared with traceable video recordings.
PCM not only is able to meet the the gold, but certainly beats in some aspects it is able to beat the gold.