the Differences Between RPR and VDRL Syphilis Tests

Consultation on RPR and VDRL Testing

Hello Dr.
Hong, thank you for your response.
I would like to ask if VDRL and RPR refer to the same syphilis testing? Because my test report only mentions RPR (STS) for the syphilis examination.
I apologize for the scattered nature of my questions, and I appreciate your time in helping me clarify this.
Thank you.

JJ, 30~39 year old female. Ask Date: 2020/07/21

Dr. Hong Yuanbin reply Internal Medicine

Hello, VDRL and RPR are the same syphilis testing methods.
Thank you for your inquiry.

Reply Date: 2020/07/21

More Info

The RPR (Rapid Plasma Reagin) and VDRL (Venereal Disease Research Laboratory) tests are both non-treponemal tests used for screening syphilis, but they are not identical. Both tests detect the presence of non-specific antibodies that are produced in response to the presence of syphilis, but they differ in their methodology and sensitivity.

1. Test Methodology:
- RPR: This test uses a flocculation method, which means it detects the formation of visible clumps when the patient's serum is mixed with a reagent containing cardiolipin, lecithin, and cholesterol. The presence of these clumps indicates a positive result.

- VDRL: This test also uses a flocculation method but is performed on a slide and is more labor-intensive. It is primarily used for testing cerebrospinal fluid (CSF) rather than serum.

2. Sensitivity and Specificity:
- Both tests have similar sensitivity and specificity for detecting syphilis, but the RPR test is generally considered to be more sensitive and is often preferred for screening. The VDRL test can yield false positives due to various conditions, such as autoimmune diseases, pregnancy, and other infections, which can complicate the interpretation of results.

3. Follow-Up Testing:
- If either the RPR or VDRL test is positive, it is essential to confirm the diagnosis with a treponemal test, such as the FTA-ABS (Fluorescent Treponemal Antibody Absorption) test. Treponemal tests are more specific and can confirm the presence of syphilis by detecting antibodies that are specific to the Treponema pallidum bacterium.

4. Clinical Implications:
- A positive RPR or VDRL test indicates that further testing is necessary to confirm a syphilis diagnosis. It is crucial to interpret these results in the context of clinical symptoms and history. If you have symptoms consistent with syphilis or have been exposed to someone with syphilis, it is important to follow up with your healthcare provider for further evaluation and treatment.

5. Your Test Report:
- If your report states "RPR (STS) syphilis test," it indicates that the RPR test was performed. If you have questions about the results or their implications, it is advisable to discuss them with your healthcare provider, who can provide personalized guidance based on your medical history and any symptoms you may be experiencing.

In summary, while RPR and VDRL tests are both used for syphilis screening, they are not the same. The RPR test is more commonly used and is generally preferred due to its sensitivity and ease of use. If you have further questions or concerns regarding your test results, please consult your healthcare provider for more detailed information and advice tailored to your situation.

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