American Board of Family Medicine (ABFM) Practice Exam

What is the next step if there is a strong suspicion for syphilis and the RPR test is negative?

1. A spinal fluid analysis

2. A serum fluorescent treponemal antibody absorption (FTA-ABS) test

3. A Venereal Disease Research Laboratory (VDRL) test

4. Repeat the RPR test in 2 weeks

The correct answer is: Repeat the RPR test in 2 weeks

In the context of a strong suspicion for syphilis, even with a negative RPR (Rapid Plasma Reagin) test, the appropriate next step is to perform a serum fluorescent treponemal antibody absorption (FTA-ABS) test. The FTA-ABS test is a treponemal test that specifically detects antibodies to the Treponema pallidum bacterium, which causes syphilis. This test is much more sensitive than the RPR, particularly in early infections where the RPR may yield a false negative. In cases where syphilis is suspected due to clinical signs or high-risk exposure, the FTA-ABS can confirm the diagnosis regardless of the RPR result. This is because treponemal tests remain positive long after the infection has been treated or resolved, contrasting with non-treponemal tests like the RPR, which may show negative results in certain circumstances, including the early stages of syphilis or if the individual has had previous treatment. Spinal fluid analysis is more appropriate when there is a concern for neurosyphilis, which would not be warranted solely on the basis of a negative RPR and suspicion of syphilis. The VDRL test is similar to