Syphilis serology, read as a posterior

Testing algorithm
Pretest probability of infection
Clinical stage — shifts the sensitivities
Stage presets reset the test characteristics

Sensitivities move most across stages; specificities barely. Edit any value below to override.

Your patient's result
What the number means
  • The posterior is P(genuine T. pallidum infection) — active, latent, or past/treated. It does not by itself separate active from treated disease; that is the work of the RPR titer plus treatment history.
  • Defaults are editable literature ballparks for Tp EIA/CIA, RPR, and TP-PA — set them to your lab's validated performance and local stage mix. Sensitivities move a lot by stage; use the toggle.

Educational tool · not a substitute for clinical judgment, titers, or direct detection (darkfield/PCR).