title: False-negative syphilis screening due to change in temperature.
abstract: OBJECTIVE
  Inaccurate test results for syphilis may cause an individual to experience serious effects.
  
  
  OBJECTIVE
  Investigate potential sources of error and test limitations causing false-negative reactions.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston.
authors: M M
authors: MM
authors: el-Zaatari
authors: M G
authors: MG
authors: Martens
mesh_terms: D015982:Bias; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood* / Q000453:epidemiology / Q000517:prevention & control; D012034:Refrigeration; D013048:Specimen Handling / Q000379:methods*; D013587:Syphilis / Q000097:blood* / Q000453:epidemiology / Q000517:prevention & control; D013588:Syphilis Serodiagnosis / Q000379:methods*; D013696:Temperature