Abstract:

Objective To improve the ability of clinical laboratory examiners to detect and identify parasites through reviewing and analyzing the results of the external quality assessment of parasite morphology. Methods A retrospective analysis of 200 samples from the external quality assessment of parasite morphology from 2013 to 2020 was conducted,of which 120 samples were from the National Center for Clinical Laboratories and the other 80 samples from the College of American Pathologists（CAP）. The accuracy of external quality assessment was calculated,the reasons for misidentification of parasites（eggs） were analyzed,and the morphological characteristics and identification points of rare and similar parasites were summarized. Results Of the 200 samples,195 samples were identified correctly（an accuracy rate of 97.5%）. Of the 80 CAP samples,77 samples were identified correctly,3 samples were identified incorrectly（an accuracy rate of 96.3%）,and 12 samples were not graded. Of the 120 samples from the National Center for Clinical Laboratories,118 samples were identified correctly,with only 2 identification errors（an accuracy rate of 98.3%）. Totally,30 parasites in 47 different life-history forms were involved in the external quality assessment of parasite morphology. The morphologically similar parasite eggs in identification included Diphyllobothrium latum eggs,Paragonimus westermani eggs,Hepatella hepatica/Fasciolopsis buski eggs,Ascaris lumbricoides eggs and hookworm eggs,hookworm eggs and Trichostrongylus orienatalis eggs,microfilaria-Brugia malayi and microfilaria-Wuchereria bancrofti. The rare parasite eggs identified were Hymenolepis nana eggs and Hymenolepis diminuta eggs. Food residue and parasite eggs in stool,as well as different kinds of cysts,were also identified. Conclusions Periodically retrospective analysis of the laboratory external quality assessment data of parasites,regular review of mixed egg samples under a microscope,review of parasite archives,and morphology review of rare and similar parasites（eggs） can improve the quality of parasite laboratory and improve the capabilities of clinical laboratory examiners.

Key words: Parasite, External quality assessment, Retrospective analysis, Morphological identification