改善陰道滴蟲於自動化尿液沉渣分析儀之偽陰性

Improving the False Negative Rate of Trichomonas vaginalis on the Automated Urine Sediment Analyzer

臨床上要確認病患是否受陰道滴蟲（Trichomonas vaginalis）感染主要由尿液沉渣鏡檢，由於人工鏡檢是相當費力耗時，因此引進自動化尿沉渣分析儀，但是陰道滴蟲的偵測率由原本千分之一降到幾乎為零。在這個研究中，以ROC的AUC評估可以區分陰道滴蟲陽性與陰性之檢驗指標，再以敏感度及專一度訂出最合適的閾值。我們發現Leukocyte esterase、Epithelial cells及WBC等三項指標對於區分陰道滴蟲陽性與陰性之分辨性最佳（AUC介於0.747 ~0.830，p<0.001）。若三項指標合併使用，則女性敏感度可達90.3%，男性則為64.8%。

Trichomonas vaginalis (TV) is the most prevalent nonviral sexually transmitted infection in women. Direct microscopy of urine sediment is the traditional method of identifying TV in the laboratory. However, the TV positive rate significantly dropped from 1.0‰ to almost zero because of the increasing uses of automated urine sediment analyzer instead of direct microscopy in recent years. We collected retrospective data, including urine routine and sediment examination in the clinical laboratory, Chang Gung Memorial Hospital. All chemical parameters from urine dipstick and conventional microscopic examination were calculated AUC by SPSS to determine the cutoff value for TV (+). We found that Leukocyte esterase (LEU), Epithelial cells (EC) and White blood cells (WBC) play the crucial roles in TV identification (AUC under ROC curve ranged from 0.747 to 0.830, p<0.001). When the individual criteria was set for EC (male>10/μL; female>15/μL), WBC (male>15/μL; female>40/μL) or LEU (≥1+), the specificity for TV can reach to 80.4%~97.6%. If combined with all three criteria, the sensitivity for TV can go up to 91.6% in women and 64.9% in men. These criteria will be very helpful to assist MTs to examine TV in urine routine testing without any additional cost.