Abstract:

Objective To investigate preliminarily the process of serological screening for syphilis in pregnant women. Methods A total of 548 serum samples of pregnant women with anti-Treponema pallidum（TP）antibody S/CO ratio ≥1.0 screened by chemiluminescence immunoassay（CLIA） were collected and were retested by chemiluminescence microparticle immunoassay（CMIA）,toluidine red unheated serum test（TRUST） and western blotting. The positive predictive values of single method and combined method were analyzed respectively based on the western blotting results,and the serological screening process for syphilis in pregnant women was established. Results There were 548 samples with anti-TP antibody S/CO ratio ≥1.0 determined by CLIA,among which 494 cases were positive, 11 cases were indeterminate（eliminated）, and 43 cases were negative determined by western blotting. Totally,295 samples were positive,and 253 samples were negative determined by TRUST. Totally, 490 samples were positive with S/CO ratio ≥1.0, and 58 samples were negative with S/CO ratio <1.0 determined by CMIA. The results of western blotting were used as gold standard, the positive predictive values of CLIA/TRUST/CMIA（+/-/-）, CLIA/TRUST（+/-）, CLIA/TRUST/CMIA（+/-/+）, CLIA/TRUST（+/+） and CLIA/TRUST/CMIA（+/+/+）were 22.4%, 82.2%, 97.4%, 100.0% and 100.0%, respectively. According to the receiver operating characteristic（ROC） curve, the optimal anti-TP antibody S/CO ratio of CMIA was 2.31 among CLIA/TRUST/CMIA（+/-/+） samples,the sensitivity was 94.7%, and the specificity was 100.0%. The serological screening process for syphilis was established based on the above results：prescreening by CLIA,the negative result can be issued directly,and the positive result should be tested by TRUST;the positive result can be issued,but the negative result should be retested by CMIA;issue the positive result when the S/CO≥2.31,retested by western blotting when the result was negative or S/CO<2.31, and issue the report according to western blotting eventually. Conclusions The serological screening process for syphilis has been established through the combination of 4 syphilis serological methods, which can improve the accuracy of syphilis diagnosis in pregnant women while reducing reexamination by western blotting.

Key words: Treponema pallidum, Syphilis serological test, Screening process, Pregnant woman, Syphilis