Exams and Tests
Diagnosis of syphilis includes a medical history and a physical exam. Your doctor may ask you questions such as:
- Do you think you have been exposed to any sexually transmitted infections (STIs)?
- What are your symptoms?
- Do you have sores in your genital area or anywhere else on your body?
- Do you or your partner engage in high-risk sexual behaviors?
- Have you had an STI in the past?
The physical exam may include:
- A careful examination of the skin and mouth to look for any rash or other abnormalities.
- For women, a pelvic exam to look for signs of syphilis. During the pelvic exam, your doctor will look for abnormal sores in the vagina or on the vulva, labia, rectal area, and inner thighs. These sores occur during the primary stage of syphilis.
- For men, a genital exam to look for signs of syphilis.
- For newborns, an examination of both the newborn and the mother for symptoms. The evaluation for congenital syphilis begins with a review of the mother's health and testing the mother for syphilis.
The diagnosis of syphilis is usually confirmed with one of several blood tests. This is especially true if no sores are present. If sores are present, a doctor may look at the fluid from one of the sores with a microscope to see whether syphilis bacteria are present (dark-field examination).
In the diagnosis of the primary and secondary stages of syphilis, lumbar puncture (spinal tap) is needed in some cases. A lumbar puncture may be done in adults:
- If there is evidence of tertiary syphilis (such as aortic aneurysm, gumma, or iritis) or if neurosyphilis is suspected.
- If penicillin or another recommended antibiotic cannot be used for treatment in latent syphilis. If the appropriate antibiotic cannot be used, it is important to find out whether fluid from the spinal column and brain (cerebrospinal fluid) is infected, because specific treatment methods are needed to effectively treat infected cerebrospinal fluid.
- Infected with HIV. Some experts recommend lumbar puncture in all HIV-infected people who have syphilis.
- To check whether a person is cured of neurosyphilis.
In newborns and children, a lumbar puncture may be done if:
- There are signs of congenital syphilis.
- The child's mother had syphilis and she was not treated, was not treated adequately, or was treated after the 20th week of pregnancy.
- The child's mother was treated with an antibiotic other than penicillin.
Additional testing should be done to find out if other sexually transmitted infections are present, especially:
The diagnosis of syphilis can be delayed or complicated because its symptoms are very similar to those of many other diseases and are sometimes not recognized. Syphilis has historically been called "the great imitator."
Screening for syphilis is strongly recommended for pregnant women and for people who are at increased risk for the infection.
People at high risk of contracting syphilis include those who:
- Have unprotected sex (do not use condoms or do not use them correctly). This risk is especially high among men who have sex with men (MSM).5
- Have multiple sex partners, particularly if they live in an area of the country where syphilis is more common.
- Have a sex partner who has syphilis.
- Have sex with a partner who has multiple sex partners.
- Exchange money or drugs for sex (prostitution).
- Have human immunodeficiency virus (HIV) infection.
The U.S. Centers for Disease Control and Prevention (CDC) and the U.S. Preventive Services Task Force strongly recommend that pregnant women be screened for syphilis because of the severe consequences of being pregnant while infected or having a child born with congenital syphilis. Screening should be done:3, 4
- At the first prenatal visit for all pregnant women.
- During the third trimester and again at delivery for pregnant women who have an increased risk for syphilis.