Reliability of a urine dipstick in emergency department patients

We conducted a study to examine whether a negative Chemstrip 9 result for leukocyte esterase and nitrite would reliably exclude an abnormal microscopic examination of the urine of emergency department patients. Three hundred urine specimens were subjected to Chemstrip 9 evaluations and full microscopic examinations in the microscopy laboratory. As the microscopy laboratory examination identified lower WBC and bacteria counts, increasing numbers of false-negative urine dipsticks results occurred. The results of our study reveal that the nitrite and leukocyte esterase assays miss significant microscopic findings with corresponding clinical pathology, with the nitrite examination being the less sensitive of the two tests. Based on our results, we believe it would not be prudent to use the Chemstrip 9 dipstick in the ED to exclude the presence of WBC and bacteria in the urine.