It can be very difficult for your health care provider to diagnose syphilis based on symptoms. This is because symptoms and signs of the disease might be absent, go away without treatment, or be confused with those of other diseases. Because syphilis can be hard to diagnose, you should
Visit your health care provider if you have a lesion (sore) in your genital area or a widespread rash
Get tested periodically for syphilis if your sexual behaviors put you at risk for STIs
Get tested to be sure you do not also have syphilis if you have been treated for another STI such as gonorrhea or HIV infection
Your health care provider can diagnose early syphilis by seeing a chancre or rash and then confirming the diagnosis with laboratory tests. Because latent syphilis has no symptoms, it is diagnosed only by laboratory tests.
There are two laboratory methods for making the diagnosis.
Identifying the bacteria under a microscope in a sample taken from a lesion
Performing a blood test for syphilisIf your doctor thinks you might have neurosyphilis, your spinal fluid will be tested as well.