A 30-year-old male asked:
If a syphilitic rash occurres, its in secondary syphilis, right? so if i am worried my rash might be syphilis and testing is negative i can be sure it is not, since false-negative tests occur in primary but not secondary syphilis?
2 doctor answers • 3 doctors weighed in
Dr. Jay Parkanswered
Pediatrics 52 years experience
Your hypothesis are not entirely true. False negative test on nontreponemal tests, e.g., VDRL or RPR test can still occur in individuals with high concentration of antibody against T pallidum (prozone phenomenon). Syphilis can be ruled out if both of nontreponemal & treponemal serologic test turns negative.
Reviewed Oct 26, 2022
Dr. Birendra Tandananswered
Urology 36 years experience
False neg tests can occur with any test and stage of disease. But are rare. Nothing in life or medicine is 100%. Chances are you are going to be OK so dont worry
Answered Oct 18, 2022
Last updated Oct 26, 2022
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