False-negative syphilis screening due to change in temperature

Sex Transm Dis. Sep-Oct 1994;21(5):243-6. doi: 10.1097/00007435-199409000-00001.


Background and objectives: Inaccurate test results for syphilis may cause an individual to experience serious effects.

Goal of the study: Investigate potential sources of error and test limitations causing false-negative reactions.

Study design: In 5 months, two laboratories screened 2,232 patients for syphilis by the Rapid Plasma Reagin (RPR) test.

Results: The hospital laboratory reported 5.3% (64/1,210) of patients' test as reactive on initial screening, and the research laboratory found 6.4% (78/1,210) reactive. Fourteen reactive patients were incorrectly reported negative by the hospital laboratory, as confirmed by both laboratories. A refrigerated centrifuge in the hospital laboratory possibly caused sera to be cooled before testing, producing false-negative results. When its temperature was adjusted from 4 degrees C to 27 degrees C, an additional 1,022 samples tested were consistent between the two laboratories.

Conclusion: Cold temperature produces false-negative reactions for syphilis screenings in patients' samples with titers < 1:4 dilution. Patients' samples with titers > or = 1:16 dilution were not affected. According to this study, incorrect temperatures for test sera can alter testing outcomes. Therefore, test manufacturer's directions must be strictly followed.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Bias
  • False Negative Reactions
  • Female
  • Humans
  • Mass Screening / methods*
  • Pregnancy
  • Pregnancy Complications, Infectious / blood*
  • Pregnancy Complications, Infectious / epidemiology
  • Pregnancy Complications, Infectious / prevention & control
  • Refrigeration
  • Specimen Handling / methods*
  • Syphilis / blood*
  • Syphilis / epidemiology
  • Syphilis / prevention & control
  • Syphilis Serodiagnosis / methods*
  • Temperature*