Abbott ARCHITECT Syphilis TP Chemiluminescent Immunoassay Accurately Diagnoses Past or Current Syphilis in Pregnancy

Emily H. Adhikari*, Ithiel J. Frame, Emilie Hill, Rizwana Fatabhoy, Amanda L. Strickland, Dominick Cavuoti, Donald D. Mcintire, Rita M. Hollaway

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Objective âWe evaluate diagnostic accuracy of the ARCHITECT chemiluminescent immunoassay (CIA) screening test in pregnancy, and evaluate pregnancy outcomes among screen-positive women. Study Design âSamples from routine prenatal rapid plasma reagin (RPR) tests were collected between June 22 and August 18, 2017 and frozen. Samples were batch-tested with the Abbott ARCHITECT syphilis TP immunoassay (CIA, index test). We calculated sensitivity, specificity, predictive value, and false positivity. We compared pregnancy and neonatal outcomes among screen-positive women. Results âOf 1,602 specimens, 35 (2.2%) were RPR +; of those, 24 (69%) were CIA +/Treponema pallidum particle agglutination assay (TPPA)+ and 11 (31%) were CIA-/TPPA-. Of 1,567 RPR-specimens, 14 (0.9%) were CIA +; of those, 13 (93%) were TPPA +, and one (7%) had a false positive CIA test. Sensitivity of the CIA (95% CI) was 100% (90.5-100%), specificity 99.9% (99.6-100%), positive predictive value 97.4% (86.2-99.9%), and false positive rate 0.06% (0.002-0.4%) for current or past syphilis. Among 37 CIA +/TPPA+ women, seven (19%) had RPR-negative status (Group 1), 11 (30%) had previously treated syphilis (Group 2), and 19 (51%) had active infection (Group 3). One stillbirth occurred in a woman with early, active syphilis identified at delivery; no adverse perinatal outcomes occurred among women in Groups 1 or 2. Conclusion âThe ARCHITECT syphilis TP immunoassay accurately diagnoses current or past syphilis in pregnancy. Clinical history and staging remain essential using a reverse algorithm.

Original languageEnglish (US)
Pages (from-to)112-118
Number of pages7
JournalAmerican journal of perinatology
Issue number1
StatePublished - 2020


  • Chemiluminescent
  • Diagnostic accuracy
  • Immunoassay
  • Reverse algorithm
  • Syphilis in pregnancy
  • Syphilis screening
  • Treponemal

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Obstetrics and Gynecology


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