RW blood test results: positive, negative

How many times in our lives do we take a RW test (it is possible that the referral had RW written in Russian)? Quite often, although in fact we should take it regularly for our own benefit. And how many times have we thought about what this blood test is and what it is for? Perhaps not even once. So maybe it is time to lift this curtain in the theater called "life"?

Another analysis?

We have already become accustomed to taking the usual tests when visiting a doctor about any disease: a general urine test, a clinical and biochemical blood test, and sometimes, if diabetes is suspected, a blood sugar test. The need for these laboratory tests is of little surprise to anyone, even when undergoing a professional or medical examination. But what is this blood test for RW, without which it is impossible to even see a doctor, and which must be taken regularly from year to year?

The blood test for RW is otherwise called the Wasserman reaction. The author of the express method for detecting syphilis is the German immunologist August Wasserman. The serological test for the presence of the syphilis pathogen (pale treponema) in the body, popular at the end of the 20th and beginning of the 21st century, was proposed at the beginning of the last century, when many in our country did not yet know about the existence of such a venereal disease.

Syphilis is a classic venereal disease. The main way of transmission of the disease is sexual, but this does not mean that the disease cannot be contracted during a blood transfusion or in everyday life. The fact is that the pathogen remains active in the fresh physiological secretions of the patient, including saliva. So even innocent kisses can cause infection with pale treponema.

There are primary and secondary forms of the pathology. Primary syphilis develops after the pathogen enters the human body. The first and often the main symptom in this case is the appearance of a special ulcer called a hard chancre. This symptom is very specific and usually appears in the genital area, on the rectal mucosa or in the mouth (places where the infection can be introduced in most cases). At a later stage of the disease, you can notice an increase in the lymph nodes in the groin or on the lower jaw (also depends on the localization of the infection).

Syphilis is a rather insidious pathology, because after 1-1.5 months the ulcer can heal and the person stops worrying about a possible disease, considering the symptom to be an accident. However, almost immediately or after a couple of weeks an incomprehensible pale rash appears on the body, which can be found even on the palms and feet.

The rash is accompanied by symptoms resembling the onset of a respiratory viral infection: general weakness, hyperthermia, headaches, enlarged lymph nodes. But again, these symptoms are not particularly stable. The person sometimes thinks that he is absolutely healthy, then the disease again takes away his strength and manifests itself in new rashes and an increase in temperature.

Sometimes they talk about the third stage of the disease, which would be more accurately called a complication of the second stage. If the disease is not treated, in the future one can expect various disorders of the nervous system, deterioration of the condition of bones and joints, failures in the work of internal organs, etc. Moreover, during the entire period of the disease the patient poses a danger to others, and even in those periods when it seems that the disease has retreated.

The disappearance of the symptoms of the disease can be considered a merit of the immune system, which is trying to fight the infection with varying success. But getting rid of pale treponema is not so easy. Special treatment is required, which is more effective the sooner the disease is detected.

But it is important to understand that the disease does not manifest itself immediately. There is a certain incubation period between the moment the pathogen enters the body and the appearance of the first symptoms of the disease. For syphilis, this period is quite long. When analyzing blood for RW, primary syphilis can be diagnosed only 6-8 weeks after infection. A positive result will be found in 9 out of 10 subjects. Secondary syphilis is detected in almost all cases of the disease.

But there is also such a variant of the disease as bacterial carriage. In a person with a strong immune system, pale treponema cannot actively reproduce, but it does not die either. In this case, there are no symptoms of the disease, but the individual remains dangerous to others, since living bacterial cells remain in his blood and secretions, which, when exposed to favorable conditions, become very active and lead to the development of syphilis.

In case of bacterial carriage, the presence of dangerous bacteria in the body is not externally determined. Only special studies can help diagnose the pathological condition, which includes a blood test for RW. Moreover, with the help of this study, it is possible to estimate how long the infection has been in the body, which makes it possible to identify potential patients and carriers of the infection, specifying data on sexual partners and possible episodes of blood transfusion involving the patient.

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Indications for the procedure an RW blood test

In fact, the RW test is considered a standard procedure in clinics, which allows to detect or exclude the presence of pale treponema in the patient's body and prevent the spread of the disease. In theory, such an important test should be regularly taken by all adults who are sexually active, as well as those who received someone else's blood transfusion 2-3 months ago (especially in emergency situations, when there is simply no time to wait for test results, because it is a matter of life and death).

But in practice, only those who undergo a medical examination in connection with the performance of professional duties that include contact with people or food products regularly take such an analysis. This category of people includes doctors, teachers, cooks, pastry chefs, beauty salon workers, etc.

Blood donation for the Wasserman reaction is mandatory for women who register for pregnancy. The test is repeated at 30 weeks of pregnancy, because the disease is easily transmitted from mother to child during passage through the birth canal.

RW analysis is considered one of the mandatory laboratory tests before surgery or during a medical examination. Drug addicts and people with alcohol dependence, blood, sperm and organ donors, as well as those who have been in contact with a sick person are also subject to preventive examination.

Indications for prescribing an RW test are the presence of the following symptoms:

• enlarged lymph nodes in the groin area,
• detection of a specific ulcer (hard chancre) in the genital area or a pale rash throughout the body,
• the presence of copious genital discharge,
• pain in bones and joints (according to patient complaints).

The appearance of specific rashes even without analysis may indicate their cause, but the remaining symptoms should be considered in combination to make a preliminary diagnosis. If the above symptoms are present, a referral for analysis is given by the doctor who examined the patient. This may be a gynecologist for women or a urologist for men, less often a virologist or andrologist may suspect syphilis (not every hospital has such specialists).

In principle, a therapist who has discovered a specific ulcer on the oral mucosa, especially against the background of enlarged regional lymph nodes, can also suspect syphilis and issue a referral for RW. Less often, a proctologist detects ulcers of the rectal mucosa, but he can also refer the patient for additional testing.

In principle, the patient himself can initiate a serological test for syphilis if he has doubts about the health of a casual (less often permanent) sexual partner. This is especially true for victims of sexual violence who do not choose a sexual partner and therefore are exposed to additional danger. In this case, shame should be the last thing to worry about, because health is much more important. And the sooner the disease is detected, the greater the chance of quickly getting rid of it before it causes significant harm to the body. Moreover, it is unknown what other infections and viruses may be lurking in the rapist's body and what this may mean for his victim.

But you should always remember that a specific analysis can detect the pathogen in the patient’s blood no earlier than 6 weeks after sexual contact, so there is no need to rush.

Some clinics and medical centers offer a comprehensive laboratory test service. The complex includes tests for HIV, RW, hepatitis B and C. Such an examination is not always necessary, but there are situations when it makes sense to get a comprehensive checkup.

What situations could these be? A comprehensive examination is recommended for expectant mothers who are planning a pregnancy or registering with a women's health clinic. After all, syphilis, hepatitis, and the human immunodeficiency virus are transmitted through blood. So, caring for the health of future generations requires special attention.

If the mother is diagnosed with at least one of the infections during pregnancy, blood will also be taken from the baby for testing after the birth.

Healthcare workers, especially those working in drug addiction clinics, are also at risk for all three diseases. By the way, blood tests in patients preparing for surgery also serve as preventive measures. Thus, doctors know what they are dealing with and will be especially careful and cautious when there is a risk of infection.

A comprehensive examination will also be useful for those who have had sexual contact with a partner whose health status is unknown. A person can be a carrier of any of the listed infections that are transmitted sexually and through blood, so it is better to immediately check for all possible diseases.

Such examination is simply necessary for drug addicts, who have the highest risk of infection, especially when using the same syringe, as well as for homeless people and alcoholics who are not very selective in their sexual relations.

And, of course, it wouldn’t hurt to get examined if you have suspicious symptoms: strange discharge from the genitals, an incomprehensible rash on the body, a prolonged increase in temperature, pain in the liver, a deterioration in general condition, a sharp decrease in immunity.

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Preparation

Any laboratory tests in medicine require certain conditions under which their results will be as accurate as possible. Doctors usually remind patients of such conditions when they write out a referral for the test.

Probably, everyone already knows that blood tests should be taken on an empty stomach, unless, of course, the doctor gives other instructions. The RW test is no exception. It should be taken in the first half of the day, preferably in the morning before breakfast, so that no food products or enzymes can affect the reliability of the results.

The last meal, according to experts, should be no later than 6, and preferably 12 hours before the test. At the same time, it is not recommended to consume fatty foods, fruit juices, coffee and coffee-containing products during the day before the procedure. It is also worth refraining from drinking alcohol and smoking. As for the latter, it is worth being patient at least the night before the test and the part of the day that remains before the procedure.

It is also advisable to avoid taking any medications, especially foxglove-based products. If this is not possible, you should inform your doctor and nurse about the medications you are taking, which will be taken into account when interpreting the test results.

However, drinking water is not prohibited even on the eve of laboratory tests. But it must be boiled or purified water without gas, which in no way can affect the results of the analysis.

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Technique an RW blood test

Venous blood is needed for the syphilis test. During the procedure, the person must sit or lie down. The nurse ties the arm above the elbow (in the forearm area) with a tourniquet and asks the person to actively "work" with the fist, i.e. bend and straighten the fingers. This is necessary to increase the flow of venous blood and the filling of the vein. If the vein is poorly visible, you can miss it or accidentally puncture it through.

When the vein becomes visible enough, the tourniquet is removed, the skin at the puncture site is treated with alcohol and the syringe needle is inserted into the vein. Having collected the required amount of blood (usually about 5-10 ml) into the syringe using the plunger, the needle is removed and a cotton ball soaked in alcohol is applied to the puncture site of the vessel. After this, the arm should be kept bent at the elbow for several minutes to reduce the blood flow and prevent bleeding.

If it is necessary to take blood from an infant, which often happens if syphilis is detected in the mother, the jugular or cranial vein is used as a source of biological material for research.

The blood is then placed in a clean test tube, in which it is delivered to the laboratory.

Blood test for syphilis (blood test for RW) is based on the body's (immune system's) ability to produce specific antibodies to antigens of foreign substances entering the human body. Antibodies of acquired and innate immunity bind to antigens and cause the death of the latter.

The causative agent of syphilis is considered to be pale treponema, containing a non-specific antigen - cardiolipin, which can also be obtained from the heart of a bull (usually sold ready-made with instructions for it). The presence of antibodies cannot be determined by eye, but if an antigen is introduced into the blood or blood serum and appropriate conditions are created (the composition is kept in a thermostat at a temperature of 37 degrees for about an hour), the antibodies and complement (proteins of innate immunity) present in it will form strong bonds with the antigens.

Next, the hemolytic system is introduced into the composition and it is observed for 0.5-1 hour whether the hemolysis reaction (physiological destruction of red blood cells from the hemolytic system) occurs. If this happens, it means that the syphilis pathogen is not in the body. The absence of hemolysis or its delay compared to the control sample indicates that the antibody-antigen binding reaction has occurred. The magnitude of the delay is used to judge the extent of the body's damage by the disease.

The Wasserman reaction belongs to the category of complement fixation reactions (CFR), which help to identify the pathogen in the body, but do not show particular accuracy and depend on many factors, which is why they give a significant percentage of false positive results.

How long does it take to do a blood test for RW? One day is enough to conduct the tests, and the doctor receives the test results the next day. Usually, tests to determine the pathogen take much longer, so the Wasserman reaction is also called an express test for RW.

The validity period of the RW test is no more than 3 months, but it is usually required to be taken at least once a year during a medical examination. But there is a small but important nuance here. It is recommended to take blood for RW more than once, since the test is very sensitive to various factors and can give false results. In addition, the long incubation period does not allow identifying the pathogen immediately after it has entered the body. At least 4 weeks must pass after infection for the test to show the presence of bacteria in the blood.

Normal performance

As usual in laboratory test results, a positive result indicates the presence of a pathogen in a biological sample, while a negative result indicates that the person is healthy. That is, a negative response in laboratory tests is considered normal.

What does a blood test for RW show? The presence or absence of the syphilis pathogen in a person's body based on the reaction of his blood to the introduction of an antigen similar to the pale treponema antigen. A negative result is usually indicated by a minus sign ("-"), as in school algebra. Accordingly, a positive result is written as a plus ("+"). But when deciphering an RW test, everything is not so clear.

The minus here means a negative result, i.e. the absence of the pathogen. But a positive result, depending on the magnitude of the hemolysis delay, is indicated by a certain number of pluses:

• 4 pluses (++++) indicate that the hemolysis reaction did not occur, and this is irrefutable proof that the body contains the pathogen and in large quantities (a sharply positive Wasserman reaction),
• 3 pluses (+++) indicate a significant delay in hemolysis, which also indicates the presence of bacteria in the body, but in smaller quantities (positive blood test for RW),
• 2 pluses (++) indicate a partial delay in hemolysis, i.e. in some test tubes hemolysis did occur, but in others it did not (weakly positive analysis for RW), which can be interpreted in two ways,
• 1 plus (+) indicates a slight delay in hemolysis, which in principle does not mean anything specific, so a retest will be prescribed (questionable RW test).

In principle, it is better for those who have 2 pluses on the form to re-donate blood, since there is a high probability that the person is not a carrier of pale treponema, and a false positive RW test is associated with completely different pathologies or conditions of the body.

A positive test result in a healthy woman may be due to pregnancy, the postpartum period, or menstruation. And the culprit will be a hormonal imbalance during these time periods, which caused a malfunction in the immune system.

Severe diseases, especially viral ones, significantly weaken the immune system, and it begins to work incorrectly. This is manifested by the production of antibodies to the small amount of cardiolipin that is also present in the human body, although this has not been observed before. Therefore, if the analysis was taken just a couple of days after pneumonia, severe acute respiratory viral infection, hepatitis, malaria and some other diseases, there is a high probability of an error and a positive result.

Certain chronic or long-term diseases, such as tuberculosis, diabetes, rheumatism, lupus, leprosy, oncological pathologies, and HIV infection, also significantly reduce immunity. They may also cause a false positive result.

A similar situation can be observed in recently born children up to 10 days old, as well as in those who have recently been vaccinated.

An incorrect result can also be expected in cases where the person donating blood has:

• the temperature is elevated,
• there is an infectious disease, or the study is carried out immediately after the illness,
• not enough time has passed since infection (during the first 2-3 weeks the result will most likely be negative, which does not indicate sexual health).

It is clear that the prohibitions on eating fatty foods, alcohol, certain types of drinks, smoking and taking drugs containing alkaloids are not empty words, because these are the very things that can distort the test results, which will not help in diagnosing syphilis.

The way out of this situation is to repeat the blood test after some time or to use other, more modern and accurate methods of laboratory testing for syphilis: enzyme-linked immunosorbent assay (ELISA), passive hemagglutination reaction (PHAR), immunofluorescence reaction (IFR), treponema immobilization reaction (TIR), etc.

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Interpretation of results depending on the stage of the disease

False RW test results are not always associated with diseases or hormonal imbalances in the body. Sometimes the cause of an incorrect answer is taking the test during the incubation period of the disease, which can last from 6 to 8 weeks. During the first 2-4 weeks, almost all infected people will test negative, as if the person is healthy, which is not the case.

And even 5-6 weeks of illness can show the presence of infection only in a quarter of the patients studied. But closer to the 8th week after infection, only a tenth of patients have a negative test result. In the rest, the diagnosis is confirmed.

Secondary syphilis is characterized by a positive reaction from the very beginning of the disease, as is early congenital syphilis. But secondary infection often does not proceed monotonously. That is, it is characterized by periods of exacerbation and remission, when the disease proceeds latent, without visible symptoms. During this period, the RW test may be negative due to low treponema activity. But this does not indicate that the person is healthy. The immune system simply began to actively fight the disease, which led to a lull. But in prognostic terms, this is a favorable symptom.

When it comes to complications of syphilis (tertiary infection), in the acute period only a quarter of cases will have a negative result, while when symptoms subside, most patients will have such a response. But this again does not indicate recovery. The infection is simply lurking in the body and waiting for its time.

Late congenital syphilis, unlike early, is diagnosed in children over 5 years of age, and sometimes in adults. The acute onset of the disease resembles acquired syphilis and is characterized by a positive laboratory test result in about 75% of cases. When the symptoms subside, the result becomes negative in most cases.

But the RW blood test is a valuable test not only from the diagnostic side. With its help, it is possible to monitor the effectiveness of the prescribed antisyphilitic treatment and identify resistant forms of the disease, in which there is no point in continuing the prescribed therapy.

In principle, using the Wasserman reaction, used in combination with other methods, it is possible not only to detect the pathogen in the patient's body, but also to determine the period during which the pale treponema parasitizes inside a person, which allows differentiating primary infection from secondary and tertiary ones.

The RW test was once a very popular test, as it was the only one that allowed diagnosing syphilis with a sufficient percentage of accuracy. But later, more objective methods with fewer false positive and false negative results appeared, and the Wasserman reaction gave way to them. Nevertheless, even some private clinics still work with this relatively inexpensive test, combining it with hepatitis and HIV tests.

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