Urine Transparency as an Index of Absence of Infection

Summary— A visual assessment of the clarity of urine was used as an exclusion test to indicate the absence of infection; verified by dipslide culture, it was applied to 363 urine samples collected from patients attending 2 adult nephrology clinics over a period of 6 months. The crimped aluminium bowl used for collection of samples assisted the assessment of clarity. The sensitivity of the method compared with dipslide culture was 73%, with specificity and efficiency both 58%. The predictive value of a negative test (clarity) was 97% with a false negative rate of 3%, enabling this simple examination to be used as an exclusion test for further testing. In simple terms, a clear urine is unlikely to be infected. It is also an advantage to have an immediate indicator of the absence of infection available at the clinic. Analysis of only those urines assessed as cloudy could result in financial savings and, from the clinics, a 56% reduction in workload.