The VDRL, which stands for Venereal Disease Research Laboratory, is a blood test used to diagnose syphilis which is a sexually transmitted disease. In addition, this test may also be requested to accompany the disease in those who already have syphilis, which is characterized initially by the presence of wounds in the intimate region that do not hurt. See what are syphilis symptoms.
In some cases the syphilis test may give a false positive result, which may mean that the person does not have syphilis, but may have other diseases, such as leprosy, tuberculosis or hepatitis, for example.
The VDRL exam must be performed before becoming pregnant and also in each trimester of pregnancy as it is a disease that can have serious health complications.
How the VDRL exam is performed
The VDRL test is done through a simple blood test, where a small blood sample is collected and analyzed in the laboratory.
To do the test, fasting is not necessary, although some doctors or laboratories indicate fasting for at least 4 hours to perform the test. The result of the test is released according to the laboratory, and can be released between 24 hours or in 7 days.
How to interpret the VDRL test results
The VDRL test result is given by titles, the bigger the title the more positive the test result is. The VDRL test result can be:
- Positive or Reagent;
- Negative or Non reactive;
If the result is negative, it means the person never came into contact with the bacteria that caused syphilis or that it is cured.
What does a positive result indicate
Normally a positive VDRL result indicates the person has syphilis. Although, the person may not have syphilis and have other diseases like brucellosis, leprosy, hepatitis, malaria, asthma, tuberculosis, cancer and autoimmune diseases, resulting in a false-positive result.
The result is considered positive when it has a title from 1/16. This title means that even by diluting the blood 16 times it is still possible to identify antibodies.
Lower titers, such as 1/1, 1/2, 1/4 and 1/8, indicate that syphilis may be present, since after one, two, four, or eight dilutions the antibodies can still be detected. As it is a possibility, it is important to return to the doctor so he can request a test to confirm the result, since these titles may be the result of a cross reaction, which is, a false positive. Low titles are also found in primary syphilis, where antibodies circulate in the blood at low concentrations.
Titles over 1/16 indicate that you have syphilis and therefore you should go to your doctor so that treatment can be started quickly.
VDRL testing during pregnancy
The VDRL pregnancy test should be performed early in the prenatal period before getting pregnant and should be repeated again in the second trimester, even if the result may be negative because the baby may have neurological problems if the mother has syphilis.
If the result is positive, the pregnant woman can transmit the disease to the baby through the placenta or birth canal if the disease is not identified and treated correctly.
When syphilis is diagnosed in the pregnant woman, the VDRL should be done every month until the end of pregnancy so that the woman's response to the treatment can be evaluated and, therefore, she can know if the bacterium causing syphilis has been eliminated.
Usually the treatment of syphilis is done with penicillin injections according to the gynecologist, obstetrician or infectologist.