CSF VDRL test

Definition

The CSF-VDRL test is used to diagnose neurosyphilis. This test looks for antibodies called reagins, which are sometimes produced by the body in reaction to the syphillis-causing bacteria. 

How the test is performed

The test is performed on a CSF sample obtained by lumbar puncture (spinal tap).

How to prepare for the test

The procedure is a lumbar puncture (spinal tap). Before the procedure, you will be asked to review the risks and sign a consent form. After the lumbar puncture is done, you will be asked to remain lying down flat for 6 hours.

How the test will feel

You will be asked to lie on your side in the fetal position with your legs curled towards your chest. The area where the needle will be inserted (in your lower back) will be thoroughly cleaned. The scrub will feel cold and wet.

You will then receive an injection at the site with local anesthesia which may sting or burn when first injected. There will be a hard pressure sensation when the needle is inserted, and there is usually some brief pain as the needle goes through. This pain should stop in a few seconds.

Usually, discomfort is mild to moderate. The entire procedure usually takes about 30 minutes but may take longer. The actual fluid collection only takes a few minutes.

Why the test is performed

The CSF-VDRL test is used to diagnose syphilis in the brain or spinal cord. Brain and spine cord involvement usually indicates a late-stage (tertiary) form of the disease. Blood screening tests, such as VDRL and RPR, are more effective during middle stage (secondary) syphillis.  

Normal Values

Sometimes, people with syphillis can have normal CSF-VDRL test result. This is called a "false-negative" result. Therefore, a negative test does not always rule out neurosyphilis. Other markers of inflammation, such as elevated protein levels or excess white blood cells, may be used to diagnose neurosyphilis.

What abnormal results mean

A reactive VDRL test when using a CSF sample indicates neurosyphilis.

What the risks are

• Risks of lumbar puncture include:
  • Hypersensitivity (allergic) reaction to the anesthetic
  • Discomfort during the test
  • Headache after the test
  • Bleeding into the spinal canal
  • Brain herniation (if performed on a person with increased intracranial pressure) which may result in brain damage or death
  • Damage to the spinal cord or nerve roots

Special considerations

Since the CSF VDRL test can have false negative results, additional tests such as protein levels and white blood cell counts may be done on the spinal fluid to diagnose neurosyphilis.

References

Illustrations

CSF test for syphilis

Page Content:

Venereal Disease Research Laboratory slide test - CSF