The VDRL exam is a laboratory test that aims to diagnose and monitor the response to treatment for syphilis, which is a sexually transmitted infection caused by the bacteria Treponema pale.
Thus, by collecting a blood sample, which is sent to the laboratory for processing, it is possible to identify the presence of circulating antibodies and their concentration, indicating the severity of the disease.
Although VDRL is one of the main tests to diagnose syphilis, it can give a false-positive result, meaning that the person may have other diseases such as leprosy, tuberculosis or hepatitis, for example, and, therefore, must be carried out together. with other tests that also confirm the infection.
What is it for
The VDRL test is used to diagnose and monitor the treatment of syphilis. This test is indicated when the person has had sexual intercourse without a condom, shows signs or symptoms of syphilis and during pregnancy, as the bacteria responsible for syphilis can be transmitted to the baby.
Syphilis is a sexually transmitted infection in which the presence of wounds in the genital region is found that do not hurt or cause discomfort and can often go unnoticed. However, if not identified and treated, the bacteria can remain in the body and lead to the development of more serious forms of the disease, whose symptoms can be noticed years after the initial infection.
Read too: Syphilis: what it is, symptoms, types, transmission and treatment
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VDRL exam during pregnancy
The VDRL test during pregnancy must be carried out at the beginning of prenatal care and must be repeated in the second trimester, even if the result is negative, as 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 the birth canal, otherwise the disease cannot be identified and treated correctly and, therefore, it is essential that treatment is started.
If a pregnant woman is diagnosed with syphilis, the VDRL test must be carried out every month until the end of the pregnancy to assess the woman’s response to treatment and thus be able to know whether the bacteria that causes syphilis has been eliminated.
Syphilis is normally treated with Penicillin injections in agreement with the gynecologist, obstetrician or infectious disease specialist. Find out more about the treatment of syphilis, signs of improvement, worsening and complications.
Do you have questions about your exam results?
The VDRL test is carried out through a simple blood test, in which a small sample of blood is collected and sent to the laboratory for analysis. In the laboratory, the blood sample is processed, added to a glass plate and mixed with reagents, with serial dilutions being carried out with the aim of checking to what extent there was a reaction, indicating the severity of the disease.
It is common for the VDRL to be done in conjunction with the RPR, which is also a test capable of identifying the presence of antibodies against the bacteria circulating in the blood, however, like the VDRL, it is not specific for the Treponema pallidum, qwhich is the bacteria responsible for the infection, and, therefore, in positive cases, treponemal tests can be performed, such as FTA-ABS and TP-PA, which are capable of confirming that it is syphilis and differentiating it from past infections.
Fasting is not necessary to carry out the exam and the result is released according to the laboratory, and can be released within 24 hours or within 7 days.
How to understand the VDRL exam result
The result of the VDRL exam is given in titers: the higher the titer, the more positive the test result. Basically the result of the VDRL exam can be:
- Positive or Reactive;
- Negative or Non-reactive.
If the result is negative, it means that the person has never come into contact with the bacteria that causes syphilis or that they have been cured.
A positive result normally indicates that the person has syphilis, however there is also the possibility of false-positive results due to cross-reactions that can occur and, in these cases, it could mean that the person may have other diseases such as brucellosis, leprosy, hepatitis, malaria, asthma, tuberculosis, cancer and autoimmune diseases.
What does the positive result mean?
The result is considered positive when it has a titer from 1/16. This title means that even diluting the blood 16 times it is still possible to identify antibodies, and it is essential in these cases that the doctor is consulted so that treatment can be started quickly.
Lower titles such as 1/1, 1/2, 1/4 e 1/8, indicate that it is possible to have syphilis, as after one, two, four or eight dilutions it was still possible to detect the antibodies. As this is a possibility, it is important to go back to the doctor so that a confirmatory test can be requested, as this titer could be the result of a cross-reaction, that is, a false positive.
Low titers are also found in primary syphilis, in which antibodies circulate in the blood in low concentrations and after treatment, in some cases. Therefore, if a person has a history of syphilis, it is possible that they will present lower titers of the disease due to the persistence of antibodies in the circulation. However, it is important that treponemal tests are carried out to check whether this result is due to past infection or is indicative of active infection, since there is no formation of immunity against the Treponema pale.
