Blood test results for RW: positive, negative

How many times in my life do we pass the analysis on RW (it is not excluded that in the direction it was written RV in Russian)? Quite often, although in fact they have to take it regularly for their own good. And how many times have we thought about what this blood test is and what is it for? Maybe not even once. So maybe it's time to open up for yourself and this veil in the theater called "life"?

Another analysis?

We are already used to contacting a doctor about a disease to take the usual tests for us: a general urine test, a clinical and biochemical blood test, and sometimes a suspicion of diabetes is also an analysis of blood sugar. The necessity of these laboratory studies is of little surprise to anyone who goes through a professional or physical examination. But what is this blood test for RW, without which even a doctor can not get to, and which you need to take regularly from year to year?

The analysis of blood on RW is otherwise called the Wasserman reaction. The author of the express method for the detection of syphilis is the German immunologist August Wasserman. Popular in the late twentieth and early twenty-first centuries, a serological study for the presence of a causative agent of syphilis (pale treponema) in the body was proposed at the beginning of the last century, when many people in our country did not even know about the existence of such a venereal disease.

Syphilis is a classic of venereal diseases. The main way of transmission of the disease is sexual, but this does not mean that the disease can not be infected during blood transfusions or in the home. The fact is that the causative agent of the disease retains its activity in fresh physiological discharges of the patient, including saliva. So even innocent kisses can cause infection with pale treponema.

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

Syphilis is a rather insidious pathology, because after 1-1.5 months the ulcer can be prolonged and the person ceases to worry about a possible illness, considering the symptom as an accident. However, almost immediately or after a couple of weeks on the body there is an incomprehensible rash of pale color, which can be found even on the palms and feet.

Symptoms resembling the onset of a respiratory viral infection join the rash: general weakness, hyperthermia, headaches, an increase in lymph nodes. But again these symptoms are not very stable. It seems to a person that he is absolutely healthy, then the disease again takes away his strength and manifests itself as new eruptions and a rise in temperature.

Sometimes we speak about the third stage of the disease, which would be more accurately called complication of the second stage. If the disease is not treated, in the future you can expect various disorders of the nervous system, deterioration of the bones and joints, disruptions in the internal organs, etc. Moreover, during the whole period of the illness the patient presents a danger to others, and even in those periods when it seems that the disease has receded.

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

But you need to understand that the disease manifests itself not immediately. There is a definite incubation period between the moment the pathogen enters the body and the appearance of the first symptoms of the disease. In syphilis this period is quite long. When analyzing blood on RW, primary syphilis can be diagnosed only 6-8 weeks after infection. Positive result will be in 9 out of 10 subjects. Secondary syphilis is found in almost all cases of the disease.

But there is also a variant of the disease, as bacteriocarrier. In a person with a strong immune system, pale treponema can not actively multiply, but does not die. In this case, the symptoms of the disease are absent, but the individual remains dangerous to others, because in his blood and secretions there are living bacteria cells that, when they get into favorable conditions, become very active and lead to the development of syphilis.

In the case of bacterial transport, the presence of a dangerous bacterium in the body is not externally determined. To help diagnose the pathological condition can only special studies, which includes a blood test on RW. Moreover, this study can assess how long the infection is in the body, which makes it possible to identify potential patients and carriers of infection by specifying data on sexual partners and possible episodes of blood transfusion involving the patient.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]

Indications for the procedure of the blood test on RW

In fact, the analysis on RW is considered in polyclinics as a standard procedure that allows to identify or exclude the presence of pale treponema in the patient's body and prevent the spread of the disease. On the idea of such an important study, it would be necessary to regularly go to all adults who have an active sexual life, as well as those who were transfused with someone else's blood 2-3 months ago (especially in emergency conditions, when there is simply no time to wait for the test results, to life, and to death).

But in practice such an analysis is regularly passed only by those who pass medical examination in connection with the performance of professional duties, including contact with people or food. This category of people includes doctors, teachers, cooks, confectioners, beauty salons, etc.

It is necessary to give blood to Wasserman's reaction to women who register for pregnancy. Re-examination is carried out at the 30th week of pregnancy, because the disease is easily transmitted from mother to child during the passage of birth canal.

Analysis on RW is considered one of the mandatory laboratory tests on the eve of surgery or during the passage of a medical examination. Also, drug users and people with alcohol dependence, donors of blood, sperm and organs, as well as those who contacted the sick person are subjected to preventive examination.

Indications for the appointment of the RW assay are the presence of the following symptoms:

• an increase in lymph nodes in the groin area,
• the detection of a specific ulcer (solid chancre) in the genital area or pale rash throughout the body,
• the presence of abundant genital secretions,
• pain in the bones and joints (on complaints of patients).

The appearance of specific rashes even without an analysis may indicate their cause, but the remaining symptoms should be considered together in order to make a preliminary diagnosis. In the presence of the above symptoms, the direction of the analysis is given by the doctor who was examined by the patient. It can be a gynecologist in women or a urologist in men, less likely to suspect syphilis may be a virologist or andrologist (such specialists are not in every hospital).

In principle, suspected syphilis and write a referral to RW can and the therapist, who found a specific ulcer on the oral mucosa, especially against the background of an increase in regional lymph nodes. Less often reveals ulcers of the rectal mucosa proctologist, but it can also direct the patient to additional research.

In principle, the patient himself can initiate a serological test for syphilis if he has doubts about the health of an occasional (rarely permanent) sexual partner. This is especially true for victims of sexual violence who do not choose their 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 a disease is discovered, the more likely it is to get rid of it, until it causes significant harm to the body. Moreover, it is not known what other infections and viruses can lurk in the body of a rapist and how this is fraught for his victim.

But we must always remember that a specific analysis can reveal a pathogen in the patient's blood not earlier than 6 weeks after sexual contact, so it's not worth hurrying.

Some clinics and medical centers offer a comprehensive laboratory research service. The complex includes tests for HIV, RW, hepatitis B and C. Such a survey is not always necessary, but there are situations when it makes sense to check all-round.

What kind of situation can this be? A comprehensive survey is shown to future mothers who plan a pregnancy or are registered with a women's consultation. Still, syphilis, hepatitis, and human immunodeficiency virus are transmitted through the blood. So care about the health of future generations requires special attention.

If a mother has at least one of the infections during pregnancy, after the birth of the baby, he will also be taken for examination.

In the risk group of all three diseases are also medical workers, especially those who work in drug treatment clinics. By the way, the study of blood in patients in preparation for surgery also carries preventive measures. Thus, doctors know what they are dealing with, and at the risk of infection will be especially cautious and neat.

A comprehensive examination will be useful to those who have had sexual intercourse with a partner, whose health state is not known. A person can be a carrier of any of the listed infections, which are transmitted sexually and through the blood, so it is better to immediately check for all the possible diseases.

Such a survey is simply necessary for drug addicts who have the highest risk of infection, especially when using a single syringe, as well as people without a permanent residence and alcoholics who are not very selective in sexual relations.

And, of course, it would not hurt to examine those who had suspicious symptoms: strange discharge from the genitals, an incomprehensible rash on the body, a prolonged temperature increase, pain in the liver, deterioration of the general condition, a sharp decrease in immunity.

[12], [13], [14]

Preparation

Any laboratory tests in medicine require certain conditions under which their result will be as accurate as possible. Usually, doctors remind patients about such conditions when they prescribe a referral for analysis.

Probably, everyone already knows that blood tests should be given on an empty stomach, unless, of course, the doctor gives other instructions. Analysis on RW is no exception. It should be taken in the morning, preferably in the morning before breakfast, so no food products and 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 analysis. In this case, during the day before the procedure is not recommended to eat fatty foods, fruit juices, coffee and coffee-containing products. It is also necessary to refrain from drinking and smoking. As for the latter, it is worthwhile to suffer at least the night before the analysis and that part of the day that remains before the procedure.

It is also advisable to refrain from taking any medications and especially on the basis of digitalis. If this is not possible, you need to notify the doctor and the nurse about the medications that will be taken into account when deciphering the analysis.

But 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.

[15], [16], [17], [18]

Technique of the blood test on RW

For analysis of syphilis, venous blood is needed. During the procedure, a person should take a sedentary or reclining position. The hand above the elbow fold (in the forearm area) the nurse bandages with a tourniquet and asks to actively "work" the fist, i.e. Bend-unbend fingers. This is necessary in order to strengthen the flow of venous blood and the fullness of the vein. If the vein is seen badly, you can not get into it or accidentally pierce through.

When the vein becomes sufficiently visible, the tourniquet is removed, the skin at the puncture site is treated with alcohol and the needle of the syringe is injected into the vein. By typing the right amount of blood (usually take about 5-10 ml) into the syringe with the help of a piston, the needle is removed, and the cotton wool soaked in alcohol is applied to the place of the puncture of the vessel. After this, the hand should be kept for several minutes bent at the elbow to reduce the flow of blood and prevent bleeding.

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

Then the blood is sent to a clean test tube, in which it is delivered to the laboratory.

The blood test for syphilis (blood test for RW) is based on the ability of the body (the immune system) to develop specific antibodies to the antigens of foreign substances that enter the human body. Antibodies of acquired and innate immunity bind to antigens and cause death of the latter.

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

Then the hemolytic system is introduced and 0.5-1 hour is observed if a hemolysis reaction (physiological destruction of erythrocytes from the hemolytic system) occurs. If this happens, then there is no causative agent of syphilis in the body. The absence of hemolysis or its delay compared to the control specimen suggests that an antibody-antigen binding reaction has occurred. The magnitude of the delay is judged by the degree of damage to the body by the disease.

Wasserman's reaction refers to the category of complement fixation reactions (RSK) that help to identify the causative agent of the disease in the body, but do not show particular accuracy and depend on many factors, because of which they give a significant percentage of false positive results.

How much is the blood test done on RW? 1 day is enough for the research, and the next day the doctor receives the results of the analysis. Usually, tests for determining the causative agent of the disease require much more time, so Wasserman's reaction is otherwise called rapid analysis on RW.

The shelf life of the RW assay is no more than 3 months, but it is usually required to take it at least once a year during a medical examination. But there is also a small but important nuance here. It is recommended to take blood on RW more than once, because the test is very sensitive to various factors and can give untrue results. In addition, a long incubation period does not allow to identify the pathogen immediately after it has entered the body. Must pass at least 4 weeks after infection, so that the test shows the presence of bacteria in the blood.

Normal performance

As usual, in the results of laboratory studies, a positive result indicates the presence of a causative agent in a biological sample, while a negative result indicates that the person is healthy. That is, a negative answer is considered normal in laboratory studies.

What does the blood test show on RW? The presence or absence of the causative agent of syphilis in the human body by the reaction of its blood to the introduction of an antigen similar to the antigen of pale treponema. A negative result is usually denoted by the minus sign ("-"), as in the algebra of the school course. Accordingly, a positive result is recorded as a plus ("+"). But when decoding the analysis on RW, everything is not so unambiguous.

Minus here means a negative result, i.e. Absence of pathogen. But the positive result, depending on the size 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 an incontrovertible proof that there is a causative agent of the disease in the body 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 a smaller amount (positive blood test for RW),
• 2 plus (++) means a partial delay of hemolysis, i.e. In some test tubes, hemolysis did occur, but in others there is no (weakly positive analysis on RW), which can be deciphered in two ways,
• 1 plus (+) indicates a slight delay in hemolysis, which in principle does not specifically mean anything, so a reassessment of the analysis will be scheduled (questionable analysis on RW).

In principle, blood transfusion is better for someone who has 2 plus signs on the form, because there is a high probability that a person is not a carrier of pale treponema, and false positive analysis on RW is associated with completely different pathologies or conditions of the body.

The cause of a positive result of the analysis in a healthy woman can become pregnancy, the postpartum period or menstruation. And the blame for everything will be the hormonal imbalance in these time intervals, which caused a malfunction in the immune system.

Severe diseases, especially of a viral nature, significantly weaken the immune system, and it starts to work incorrectly. This is manifested by the production of antibodies to the small amount of cardiolipin that exists in the human body, although previously this has not been observed. Therefore, if the analysis was done after only a couple of days after pneumonia, severe ARVI, hepatitis, malaria and some other diseases, if there is a high probability of error and a positive result.

Strongly reduce the immunity and some chronic or long-lasting diseases, for example, tuberculosis, diabetes mellitus, rheumatism, lupus erythematosus, leprosy, oncological pathologies, HIV infection. Against their background, a false positive result can also be noted.

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

An untrue result can be expected in those cases, if the person who gives the blood:

• increased temperature,
• there is an infectious disease, or the study is carried out immediately after the illness,
• there was not enough time after infection (within the first 2-3 weeks the result is most likely to be negative, which does not indicate sexual health at all).

It is clear that bans on the intake of fatty foods, alcohol, certain types of drinks, smoking and the use of drugs containing alkaloids, are not empty words, because these moments can distort the result of the analysis, which in no way will help in diagnosing syphilis.

The solution is to re-examine the blood after some time, or use other, more modern and accurate methods of laboratory testing for syphilis: enzyme immunoassay (ELISA), passive hemagglutination reaction (RPGA), immunofluorescence reaction (RIF), treponememia (RIT) immobilization reaction and etc.

[19], [20], [21], [22]

Decoding results depending on the stage of the disease

False results of analysis on RW are not always associated with diseases or hormonal imbalances in the body. Sometimes the reason for the wrong answer is the delivery of the analysis in the incubation period of the disease, which can last from 6 to 8 weeks. During the first 2-4 weeks, in almost all infected, the test will give a negative result, as if the person is healthy, which is actually not the case.

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

Secondary syphilis is characterized by a positive reaction from the very beginning of the disease, as well as early congenital syphilis. But secondary infection often does not proceed monotonously. Those. It is characterized by periods of exacerbation and remission, when the disease proceeds secretly, without visible symptoms. During this period, the analysis on RW may be negative because of the low activity of the treponem. But this does not indicate that the person is healthy. Simply the immune system began to actively fight the disease, which led to a lull. But in the prognostic plan this is a favorable symptom.

When it comes to complications of syphilis (tertiary infection), in the acute period only in a quarter of cases the result will be negative, whereas when symptoms subsided, this answer will be in most patients. But this again does not indicate a recovery. Just the infection lurking in the body and waiting in the wings.

Late congenital syphilis, in contrast to early syphilis, is diagnosed in children older than 5 years, and sometimes in adults. At the same time, the acute onset of the disease resembles acquired syphilis and is characterized by a positive result of a laboratory test somewhere in 75% of cases. When the symptoms subside, the result for the majority becomes negative.

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

In principle, with the help of the Wasserman reaction, applied in combination with other methods, it is possible not only to detect the causative agent of the disease in the patient's body, but also to determine the period during which pale treponema parasitizes inside the person, which allows to differentiate the primary infection from the secondary and tertiary.

Analysis on RW was once a very popular study, because the only one allowed to diagnose syphilis with a sufficient percentage of accuracy. But later, more objective methods appeared with fewer false positive and false negative results, and Wasserman's reaction gave way to the palm of primacy. Nevertheless, even some private clinics still work with this relatively inexpensive analysis, combining it with research on hepatitis and HIV infection.

[23], [24], [25], [26], [27], [28]