At present, in order to avoid blood waste and ensure blood quality, more and more blood stations use colloidal gold test strips for HBsAg screening of blood donors. This method is simple and fast, does not require special instruments, and has high specificity, but at work, the author It is found that there is a missed detection of the method, and the cause of the missed detection is analyzed. The report is as follows.
1 Materials and methods 1.1 Sources of specimens There were a total of 13,937 blood samples from unpaid blood donors on the streets.
1.2 Materials HBsAg colloidal gold diagnostic reagents are produced by Aikang Biotechnology Co., Ltd., and the initial retest HBsAg diagnostic kit (enzyme-linked immunosorbent assay) by Yingke Xinchuang (Xiamen) Technology Co., Ltd. and Beijing Wantai Biopharmaceutical Co., Ltd. produce.
1.2 Materials HBsAg colloidal gold diagnostic reagents are produced by Aikang Biotechnology Co., Ltd., and the initial retest HBsAg diagnostic kit (enzyme-linked immunosorbent assay) by Yingke Xinchuang (Xiamen) Technology Co., Ltd. and Beijing Wantai Biopharmaceutical Co., Ltd. produce.
2 Results 13937 blood donors were negatively screened by HBsAg colloidal gold diagnostic reagent. 36 cases were strongly positive and 15 cases were weakly positive by ELISA test.
3 The reasons for the missed detection of positive specimens are as follows.
3.1 Insufficient blood collection depth In order to obtain a sufficient amount of blood sample to squeeze, the tissue fluid is mixed into the blood, causing the antigen concentration to decrease, and the weak positive specimen is missed. Therefore, the blood collection depth should be moderate, about 2~3mm, to prevent forced extrusion.
3.2 Irregular operation When the blood of the specimen is not dialysis, a drop of buffer can be added to accelerate the blood dialysis. If the buffer is added to the test strip before the blood is added, the positive specimen will be missed.
3.3 Insufficient observation time Strong positive specimens can be detected in 2min, 5ng standard can be detected in 5min, and 1ng standard can be detected in 15min. Short observation time will cause missed detection of HBsAg weak positive specimens. When there are more blood donors on the street, in order to shorten the waiting time of blood donors, the observation time is short, resulting in a weak positive missed test.
3.4 Poor test conditions The test temperature should be kept above 10 °C, avoid wind blowing, and should be used as soon as possible in high temperature and high humidity environment. Blood donation on the street, sometimes the test conditions are difficult to guarantee, which requires the inspectors to strictly follow the requirements of the kit, and can appropriately extend the reaction time according to changes in external temperature, so as to avoid missed inspection.
3.5 Poor sample loading control Insufficient or excessive sample loading will affect the inspection results. Insufficient sample loading will result in positive missed detection, excessive loading, detection of test strip filter can not effectively block blood cells, blood cells and serum move to the detection line, resulting in blurred detection area, affecting the interpretation of results [1].
3.6 Reagent sensitivity difference The sensitivity of HBsAg colloidal gold test strip is lower than that of ELISA test. Colloidal gold test strip can detect HBsAg of ≥1ng/ml, and there is a missed detection of <1ng/ml specimen.
3.1 Insufficient blood collection depth In order to obtain a sufficient amount of blood sample to squeeze, the tissue fluid is mixed into the blood, causing the antigen concentration to decrease, and the weak positive specimen is missed. Therefore, the blood collection depth should be moderate, about 2~3mm, to prevent forced extrusion.
3.2 Irregular operation When the blood of the specimen is not dialysis, a drop of buffer can be added to accelerate the blood dialysis. If the buffer is added to the test strip before the blood is added, the positive specimen will be missed.
3.3 Insufficient observation time Strong positive specimens can be detected in 2min, 5ng standard can be detected in 5min, and 1ng standard can be detected in 15min. Short observation time will cause missed detection of HBsAg weak positive specimens. When there are more blood donors on the street, in order to shorten the waiting time of blood donors, the observation time is short, resulting in a weak positive missed test.
3.4 Poor test conditions The test temperature should be kept above 10 °C, avoid wind blowing, and should be used as soon as possible in high temperature and high humidity environment. Blood donation on the street, sometimes the test conditions are difficult to guarantee, which requires the inspectors to strictly follow the requirements of the kit, and can appropriately extend the reaction time according to changes in external temperature, so as to avoid missed inspection.
3.5 Poor sample loading control Insufficient or excessive sample loading will affect the inspection results. Insufficient sample loading will result in positive missed detection, excessive loading, detection of test strip filter can not effectively block blood cells, blood cells and serum move to the detection line, resulting in blurred detection area, affecting the interpretation of results [1].
3.6 Reagent sensitivity difference The sensitivity of HBsAg colloidal gold test strip is lower than that of ELISA test. Colloidal gold test strip can detect HBsAg of ≥1ng/ml, and there is a missed detection of <1ng/ml specimen.
[references]
1 Liu Fuchang. Analysis of the causes of missed detection of HBsAg whole blood gold standard test strip. Chinese Journal of Transfusion, 2002, 15 (3): 188.
Author unit: 266071 Shandong Qingdao, Qingdao downtown blood station
1 Liu Fuchang. Analysis of the causes of missed detection of HBsAg whole blood gold standard test strip. Chinese Journal of Transfusion, 2002, 15 (3): 188.
Author unit: 266071 Shandong Qingdao, Qingdao downtown blood station
Wenzhou Celecare Medical Instruments Co.,Ltd , https://www.celecaremed.com