Rpga 1 2560 what does it mean. How is the RPG blood test deciphered and how to prepare for it? Who orders the study

Indications for use

The main purpose of the analysis is to identify the causative agents of syphilis in the blood. The study is prescribed during the examination:

• patients with clinical symptoms of syphilis;
• persons in close contact with the patient;
• people donating blood;
• persons who issue a medical record;
• patients before surgery;
• patients before hospitalization.

The RPGA test is prescribed when planning pregnancy to confirm or exclude immunodeficiency, infectious and other diseases. Analysis helps to identify:

• focal or diffuse alopecia (baldness);
• HIV infection, AIDS;
• different forms of hepatitis;
• tuberculosis;
• measles;
• salmonellosis;
• tick-borne borreliosis;
• diphtheria;
• Infectious mononucleosis.

What does RPG negative for syphilis mean?

RPGA analysis is a technique that is one of the most important among other blood tests. With its help, you can determine the development of unpleasant intestinal-infectious diseases. But often the test is used to detect syphilis. The research has high accuracy and reliability.

RPHA stands for passive hemagglutination reaction.

RPHA is based on the phenomenon of agglutination of red blood cells, in which antigens - RPHA reagents - are adsorbed on the surface when the blood serum of a patient with syphilis is added to them.

After combining the serum of a person infected with syphilis with the RPHA reagent, agglutination (attachment or gluing) of red blood cells occurs and their precipitation occurs. The degree of adhesion depends directly on the accumulation and density of antibodies in the blood serum; for this reason, RPGA helps not only to detect the presence of antibodies, but also to identify their quantity.

The result is divided into primary and secondary infection, expressed in the manifestation of various antibodies. In primary, IgM is activated, in secondary, IgG. The accuracy of the study becomes even more specific by the second phase. If in the first phase it is about 96%, then in the second it can reach up to 99%.

The analysis is good as an independent study, but it is better to use it as a confirmatory method after a positive nonspecific study.

Due to its high accuracy, this analysis is increasingly used to confirm or refute the onset of syphilis in a patient.

Also, for greater reliability, after RPGA, another confirmatory test can be performed, for example, a “treponemal” enzyme-linked immunosorbent test.

In general, diagnostics are always carried out comprehensively, not using only one type of examination, but combining various methods that complement each other.

Anna Poniaeva. Graduated from the Nizhny Novgorod Medical Academy (2007-2014) and Residency in Clinical Laboratory Diagnostics (2014-2016).Ask a question>>

A small disadvantage, or rather a feature of the analysis, is its sensitivity even after the disease has been cured. The result remains positive throughout the life of a person who has had syphilis. For this reason, RPGA is not used to diagnose early or late disease. It is also impossible to determine the effectiveness of the treatment using this analysis.

With any positive result, there is a suspicion of infection. But from time to time a false positive reaction may occur. True, its quantitative presence usually does not exceed 3% and is caused by a number of non-infectious reasons.

In any case, the analysis should be confirmed by other additional studies.

Watch a video on this topic

Blood is taken from a vein in the usual way.

Next, the health worker mixes the collected material with the reagent in a sterile tube. The mixture is sent for mixing, which lasts about an hour.

In case of precipitation of red blood cells, the result is defined as positive.

In such a situation, the resulting serum is diluted with water and a numerical test is performed.

Despite the fact that the main indication for testing is a suspicion of syphilis infection, there are actually more reasons for ordering the test.

• identification of signs of infection by the main pathogen and the general unfavorable clinical picture of the patient;
• with enlarged lymph nodes against the background of the appearance of rashes in the form of ulcers;
• Relatives and close people who are in close contact with an infected person, who has been ill, or who has signs of infection should also be examined;
• people who wish to become blood donors are subject to examination;
• a RPHA blood test is required before surgery;
• it is possible to prescribe an analysis during an annual preventive examination;
• it is obligatory to carry out the registration of a health certificate;
• in case of suspicion of the development of some other diseases - measles, diphtheria, salmonellosis, tetanus, whooping cough.

No special measures are required to prepare for the analysis. It is important not to smoke or drink alcohol on the eve of the examination, refrain from eating 3-4 hours before the start of the examination, and drink only still water.

It is advisable not to worry.

Due to the high accuracy of the analysis, some factors that are not always related to syphilis may affect it.

• infection with other types of pathogens - tuberculosis, mononucleosis;
• pregnancy;
• taking antibiotics in advance or starting antibiotic therapy;
• oncological diseases;
• autoimmune abnormalities;
• if the patient was previously infected with syphilis, but underwent successful therapy (after the initial infection, the result of RPGA is positive for life).

RPGA is used not only for detecting syphilis pathogens. The analysis is often used to detect intestinal pathologies.

The method is also good for detecting diphtheria infection and assessing immunity after vaccination. In this case, the antibodies begin their activity the very next day after infection, which significantly speeds up the possibility of performing the analysis. In terms of accuracy and sensitivity, the RPGA method surpasses even the bacteriological method.

A blood test for RPHA is often used to detect bacillary dysentery. Moreover, its indicativeness is much higher than that of the laboratory diagnostic method through bacterial culture. The advantage of such a study is the additional possibility of determining the phase of incoming diarrhea, including acute and chronic. The analysis also makes it possible to distinguish shigellosis from endocrine system disorders, colorectal cancer and inflammatory processes in the colon.

When using a measles marker, it is possible to detect the development of measles in a potential patient.

Used as an alternative to RTGA.

Deciphering the RPGA blood test, as well as conducting the study itself, is carried out by specialists and medical workers; an uninitiated person will not be able to decipher the titre data on their own.

Typically, a quantitative ratio of over 1:640 indicates the development of an infection in the active stage; a value of a lower nature, 1:320, indicates a primary infection.

An analytical procedure is also carried out, during which various types of accumulation of material are formed at the bottom of the wells of the microplate. If the red blood cells form an even layer resembling an umbrella, this indicates an affirmative reaction to syphilis. If the red blood cells are localized in a grouped and compact manner, forming a kind of “button,” this indicates a negative result.

In the case when red blood cells gather in a small ring with a lumen in the middle, this indicates a weakly positive reaction.

This mainly means the development of a syphilis infection in the body. But an affirmative result does not always indicate only an infection.

Reasons may include:

• pregnancy;
• hepatitis types B and C;
• acute heart attack;
• syphilis in the secondary, tertiary or latent phases;
• presence of HIV infection in the body;
• injection drug use;
• connective tissue pathologies;
• leptospirosis;
• malignant neoplasms;
• tick-borne borreliosis;
• relapsing typhus;
• geographical variants of endemic syphilis;
• inflammatory processes due to syphilis;
• tuberculosis;
• bacterial endocarditis;
• extensive injuries and fractures;
• Infectious mononucleosis;
• reaction after the vaccine.

If a positive result is detected, there is only one way out - you need to urgently consult a doctor.

Only after a comprehensive examination will a specialist be able to draw a complete picture of the progressive disease and prescribe medication and additional treatment.

Drug treatment involves the use of a different range of antibiotics - penicillin, erythromycin or tetracycline. In severe cases, pyrotherapy is added, during which the patient’s body temperature is artificially increased, and intramuscular injections of antibacterial drugs. When tertiary syphilis occurs, highly toxic drugs based on the addition of bismuth can be used as an addition to antibiotics.

Treatment is carried out both by the infected person and by his close relatives and people who have recently had contacts of various types with the patient.

All home furniture, utensils and personal items are disinfected.

Traditional therapy in this case cannot be effective, so it is practically not used.

The reasons for an indeterminate or false positive result may be the following parameters:

1. Pregnancy;
2. Presence of menstruation at the time of analysis;
3. Initial period after vaccination;
4. Recent myocardial infarction;
5. Recently suffered or currently developing infectious diseases (HIV infection, influenza, smallpox, hepatitis, respiratory infections);
6. Oncological and autoimmune diseases;
7. Pathologies of the liver, kidneys and other internal organs.

None of the methods gives a 100% guarantee of an accurate result. Deviations in some cases can reach up to 10%.

For this reason, the doctor prescribes a comprehensive examination, which includes several types of research.

Serological analysis - includes nonspecific and specific tests.

This type of analysis is useful when symptoms are insufficient or absent.

Non-specific tests are:

• microprecipitation reaction - used after one month after infection;
• Wasserman reaction - used 6 weeks after the onset of infection.

For both types, blood is taken from a finger and cerebrospinal fluid.

• immunofluorescence reaction - suitable for the early stages of the disease, capillary blood or from a vein is used as the material;
• enzyme immunoassay is one of the most accurate types of analysis, used after performing nonspecific tests or as a comprehensive diagnosis;
• Treponema pallidum immobilization reaction is another common and accurate analysis, used only 4 months after infection, the material is taken from a vein;
• Immunoblotting is a new method used to confirm the results of other tests, is very accurate, but has a high cost.

Laboratory analysis is a quick and relatively inexpensive research method. The materials used are samples of ulcers and erosions, breast milk, and sperm.

If there is a negative result, additional analysis is carried out, sometimes more than once.

RPGA analysis can be called a fairly widely used method for diagnosing infectious and bacteriological abnormalities. Diseases of this nature are very dangerous both for the body of the patient himself and for those close to him. For this reason, it is important to promptly consult a doctor from the time the first signs of the disease appear to stop the spread of the disease and its transition to a chronic form.

Based on materials from 1pokrovi.ru

Detection of specific antibodies to Treponema pallidum in blood serum, used to confirm the results of nonspecific tests for syphilis, syphilis screening, examination of contact persons and blood donors.

Synonyms Russian

English synonyms

Syphilis, passive hemagglutination test; Syphilis, indirect hemagglutination test; Treponema Pallidum Hemaglutination Assay, TPHA.

Research method

Indirect hemagglutination reaction (IRHA).

What biomaterial can be used for research?

How to properly prepare for research?

Do not smoke for 30 minutes before donating blood.

General information about the study

Syphilis is a sexually transmitted infection caused by the spirochete Treponema pallidum subspecies pallidum. The entry of this bacterium into the body leads to the development of an immune response, accompanied by the production of both nonspecific (“non-treponemal”) and specific (“treponemal”) antibodies. Detection of antibodies to T. pallidum forms the basis for laboratory confirmation of syphilis. Depending on the type of antibodies detected in the reaction, serological studies are divided into nonspecificity (“non-treponemal”) and specificity (“treponemal”). The passive hemagglutination test (RPHA) is a “treponemal” test, that is, a test specific to T. pallidum.

RPHA is based on the phenomenon of agglutination of erythrocytes, on the surface of which T. pallidum antigens (RPHA reagent) are adsorbed, when serum of a syphilis patient containing specific antibodies to the spirochete is added to them. Such antibodies appear in the blood of patients with syphilis 2 (IgM) and 4 (IgG) weeks after infection. It should be noted that this period can be extended to 6 weeks. Therefore, the sensitivity of RPGA in the primary period of syphilis is somewhat inferior to the sensitivity of this method in the secondary and tertiary periods and is about 86%. The advantage of RPGA is its high specificity (96-100%), allowing this analysis to be used as a confirmatory test after a positive result of any non-specific, “non-treponemal” test (for example, anticardiolipin test, RPR). The sensitivity of RPGA in the secondary, tertiary period of syphilis, as well as in latent syphilis is 99-100%.

The sensitivity of RPHA and other “treponemal” tests exceeds that of nonspecific (“nontreponemal”) tests such as the microprecipitation reaction (MPR) with cardiolipin antigen. Therefore, recently, “treponemal” tests, including RPGA, have become more often used as a screening test for syphilis. If the result of a screening test for syphilis using RPGA is positive, a confirmatory test should be performed. In this case, it is any other “treponemal” test, but not RPGA (for example, enzyme-linked immunosorbent assay).

As a rule, the result of RPGA remains positive even after treatment of syphilis. The exception is the situation when therapy was carried out at the very beginning of the disease. Since the result remains positive for life, RPGA is not intended for the differential diagnosis of early and late syphilis. For the same reason, this study is not used to evaluate the effectiveness of treatment for the disease.

When serum from patients with syphilis is added to the RPHA reagent, agglutination (gluing) occurs and red blood cells precipitate. The degree of agglutination depends on the concentration of antibodies in the serum, so RPGA allows not only to detect the presence of antibodies, but also to determine their quantity. The result of the analysis is presented in the form of antibody titer. Any positive titer indicates possible T. pallidum infection, but false-positive reactions are possible. Significantly increased rates are characteristic of secondary and latent early syphilis.

False-positive RPGA results are observed in 0.05-2.5% of cases and are most often caused by the presence in the patient’s serum of autoantibodies (in systemic connective tissue diseases, for example, systemic lupus erythematosus), antibodies to other pathogens similar in antigenic structure to T. pallidum (Borrelia burgdorferi, saprophytic treponema of the oral cavity and genitals), as well as other physiological and pathological conditions (pregnancy, cancer, acute myocardial infarction). As a rule, the titer of a false-positive RPHA reaction is low. An exception is the results of RPGA in patients with diffuse connective tissue diseases and malignant neoplasms, when the antibody titer can reach very high values. False-positive reactions are negatived spontaneously and without a trace within 4-6 months (acute false-positive reaction, often during pregnancy) or a longer period (chronic false-positive reaction).

Given these features, the result of RPGA should be interpreted taking into account additional anamnestic and laboratory data. When confirming the diagnosis of syphilis, it is necessary to exclude the presence of other sexually transmitted infections, and also examine all sexual partners and family members of the patient.

What is the research used for?

• To confirm the diagnosis of syphilis if the result of a nonspecific screening test is positive;
• for syphilis screening;
• for examination of persons who were in sexual and close household contact with a patient with syphilis;
• to exclude syphilis in a blood donor.

When is the study scheduled?

• patient with clinical signs of syphilis (painless erosive or ulcerative defect on a solid base) and regional lymphadenopathy (primary syphilis), polymorphic skin rash, multifocal or diffuse alopecia, syphilitic leukoderma (secondary syphilis), dense elastic node with disintegration or formation of a “dry” scar ( tertiary syphilis);
• persons who were in sexual and close household contact with a patient with syphilis;
• blood donor;
• during an annual preventive examination, hospitalization in a hospital, registration of a health certificate.

What do the results mean?

Reference values: negative.

Reasons for the positive result:

• primary, secondary, tertiary, as well as latent syphilis (acquired and congenital);
• pregnancy;
• HIV infection;
• hepatitis B and C;
• injection drug use;
• acute myocardial infarction;
• diffuse connective tissue diseases;
• relapsing fever;
• leptospirosis;
• tick-borne borreliosis;
• tropical treponematoses (yaws, bejel, pinta);
• inflammatory processes caused by saprophytic treponemes of the oral cavity and genitals;
• malignant neoplasms;
• extensive trauma and fractures;
• bacterial endocarditis;
• tuberculosis;
• Infectious mononucleosis;
• post-vaccination reaction.

Reasons for negative results:

• absence of syphilis;
• the first 2-4 weeks after T. pallidum infection;
• incorrect collection of material for research.

What can influence the result?

• The test result may be false negative during the first 2-4 (up to 6) weeks after infection.

Important Notes

• The study does not allow differentiation; syphilis (T. pallidum) and other treponematoses (T. pallidum subspecies pertenue, endemicum, carateum);
• early and late syphilis.

Also recommended

• Syphilis RPR (anticardiolipin test/precipitation microreaction), titer
• Treponema pallidum, IgM, titer
• Treponema pallidum, IgG, titer
• Treponema pallidum, IgG in liquor
• Treponema pallidum, antibodies
• HIV 1, 2 Ag/Ab Combo (determination of antibodies to HIV types 1 and 2 and p24 antigen)
• Viral hepatitis B. Monitoring viral activity before starting treatment
• Viral hepatitis C. Tests for primary detection of the disease. Examination of contact persons
• Intimate – optimal – smear test for men
• Intimate – optimal – smear test for women
• Hospitalization in a surgical hospital
• Hospitalization in a therapeutic hospital

Who orders the study?

Dermatovenerologist, neurologist, general practitioner, epidemiologist.

Based on materials from helix.ru

Syphilis is an infectious disease that ranks first in terms of prevalence. And, unfortunately, the route of infection is not only sexual. Doctors, donors, people living in the same apartment with a patient - they are all at risk. To exclude syphilis, you need to donate blood for a test, for example, RPGA. This diagnostic method is accurate, effective and allows you to detect the disease at any stage (except for the incubation period).

Conventionally, laboratory diagnostic methods can be divided into two types: they look for either the pathogen itself, or the antigens that the immune system has developed for the “stranger.” RPGA for syphilis is a specific serological test that allows you to detect antibodies to the pale spirochete. If they are detected, then the test result is positive; if antibodies are not detected, the test result is negative.

To conduct the study, red blood cell diagnostics is required, or, more simply, red blood cells treated with a special solution. They are obtained by separating blood plasma from formed elements in a centrifuge. If a person is sick, then his red blood cells will carry antibodies to the antigen (pale spirochete) and attach to it, “stick together.” Accordingly, in order to detect them, you need to introduce an antigen into the blood serum and observe the reaction, which can be:

1. Weak intensity (there are no antibodies on the surface of red blood cells, the causative agent of syphilis is absent in the body or is present in an undetectable amount).
2. Moderate intensity (red blood cells have combined with the antigen, but in an insufficient quantity to clearly diagnose the disease).
3. Intense (there are a lot of antibodies on the surface of red blood cells, clusters of sticky cells have formed).
4. Sharply intense (a large number of red blood cells combine with the antigen, forming a characteristic precipitate).

In the last two cases, we can confidently assert the presence of the disease. A reaction of medium intensity requires clarifying analyzes, since two options are possible. Either the infection occurred recently and a sufficient number of antibodies have not yet developed, or the blood preparation was performed incorrectly, and the study needs to be repeated.

Is it possible to have a false positive result for syphilis? Yes, despite the high accuracy of the RPGA method (99-100%), this can happen. This is due to the fact that the immune system produces antibodies to all pathogens, and some of them are similar in structure to Treponema pallidum, for example:

• pathogens of tick-borne borreliosis and saprophytic spirochetes;

A false positive result is also possible in the presence of autoimmune diseases, myocardial infarction and pregnancy. And if the clinical picture does not indicate syphilis and there are doubts, you need to take another test that clearly confirms or excludes the disease.

Factory-made treponeme strains or recombinant antigens isolated from them are used as antigens. Treponema cultures are grown in test tubes and treated with ultrasound. They are then quickly frozen, dried under low pressure, and the resulting powder is packaged into ampoules.

Since the intensity of the reaction varies when performing such an analysis, this served as the basis for using this method not only for diagnosis, but also for tracking the dynamics of the disease. Therefore, RPGA is conventionally divided into two subtypes.

Any analysis that answers the question: whether there is a pathogen in the body or not is called qualitative. Often this is enough to diagnose the disease and begin treatment.

However, one should also take into account the fact that antibodies to the causative agent of the disease remain in the body forever. And if a person fell ill with syphilis, underwent treatment and recovered, even decades later antibodies will be detected in his blood. How, then, can you find out whether infection has occurred again or not? The answer to this question is provided by semi-quantitative analysis of RPGA.

It is impossible to calculate the number of antibodies to spirochete pallidum. However, in order to approximately estimate their quantity, the test sample is titrated. To determine syphilis rpg semi-quantitatively means to successively dilute the serum until the moment when “clumped” red blood cells are no longer detectable. Accordingly, if there are few of them, a small number of dilutions will be required, and if there are many, they will have to be diluted in a large volume of titrant.

As a test sample, 3-5 ml of venous blood is taken from the patient. It is better to take the test in the morning; the day before the test you should exclude from your diet:

• fatty foods and salty foods;

Why do you need to follow a diet before taking the test? First of all, this is necessary so that the resulting blood sample can be worked with. For example, after eating protein and dairy products, the number of fat microparticles in the blood increases. After separation in a centrifuge, the blood plasma will appear as a cloudy, whitish serum. It is either very difficult or even impossible to separate red blood cells from such material.

Alcohol reduces the body’s protective functions, and therefore the ability to produce antibodies to pathogens. Therefore, the analysis may show either a weak or false negative reaction. In addition, ethanol affects the quantitative indicators of blood cells, which also complicates the analysis.

You cannot be tested for syphilis during the acute phase of a viral disease. Antibodies to the virus may show a false positive reaction. You definitely need to consult a doctor who will tell you when the diagnosis can be made.

You can also watch a video where a urologist-venereologist will tell you what the RPGA analysis is.

RPGA is a modern and highly accurate analysis that makes it possible to confirm or exclude syphilis with a high degree of probability. However, the final diagnosis takes into account all factors: the clinical picture, medical history, and the results of other tests. And, of course, only a doctor should interpret the results of any study.

Based on materials from myvenerolog.com

The RPHA blood test is one of the classic diagnostic methods that have been used for many decades, but are still relevant. Why is RPGA currently being carried out? Why is it sometimes preferred to modern methods, and when might an ordinary person encounter the need for such research?

The most modern method of modern laboratory diagnosis of infectious diseases is the polymerase chain reaction (PCR), which makes it possible to determine in any biological material, from blood to scrapings from mucous membranes, the remains of the genome, or the unique hereditary code of the pathogen. The second diagnostic method is the determination of immunoglobulins of class M and G in the patient’s blood, which indicate the development of a specific immune response.

This research method (passive hemagglutination reaction, RPHA) also has a second name: indirect hemagglutination reaction (IRHA). And in practice, you may encounter both the abbreviation RPGA and RNGA. What kind of analysis is this? It requires centrifuged patient blood serum, which is combined with a special diagnostic reagent. Classically it is called “erythrocyte antigen diagnosticum”. Red blood cells, or erythrocytes, have been used for its preparation for many years. But this was the case relatively long ago, and nowadays biological material is no longer used, and microscopic latex particles are used instead.

Using a special technology, these particles are coated with antigens characteristic of a given infectious pathogen, which are its “calling card.” The result is a multitude of particles on the surface of which there are active antigen molecules adsorbed and tightly bound to the carrier.

If the patient’s blood serum contains antibodies produced to a given pathogen, then these latex particles or red blood cells are glued together by the antibodies and precipitate, which is called agglutination (translated as “gluing”). This reaction is carried out in special tablets, which are made of plastic and designed for small volumes. Previously, a blood test for RPHA was carried out using a set of ordinary test tubes. They contained the patient’s blood in different dilutions, to which the diagnosticum was added.

In some cases, the mirror method is used, when the diagnosticum contains not antigens, but antibodies. This method (RONGA, or reverse hemagglutination) is used when searching for infections in which toxins circulate in the blood, such as botulism. In this case, if the patient has botulinum toxin in the blood, it binds to specific antitoxic diagnostic antibodies, and an agglutination reaction is also observed, which can be determined depending on the dilution of the blood serum.

The decoding consists of the very fact of agglutination, and the maximum dilution of blood serum at which it can still be reliably determined. The more diluted the blood, in which there is still agglutination, the more antibodies there are in the patient’s body, and the higher the specific intensity of the immune system during the classical implementation of this reaction. The most commonly used dilutions are from 1:20 to 1:160 and higher. Currently, indirect RNGA is most often used for the primary diagnosis of syphilis.

Blood test RPHA - what is it for syphilis? This is a reaction in its classic form, in which circulating antibodies to the causative agent of syphilis are detected in the patient’s blood serum. This method is inexpensive, fast, and allows the primary use of biological material for screening for this infection, for examining donors who donate blood, and for contact persons who have close contact with patients.

Thus, RPGA for syphilis is a method of primary nonspecific laboratory diagnosis. But this does not mean at all that if such antibodies are detected, then this analysis can be considered unreliable. Detection of antibodies to the pallidum spirochete is the basis for laboratory diagnosis of syphilis and its confirmation. And the passive hemagglutination reaction is classified as a specific or treponemal test, since it uses “real” syphilitic antigens.

After blood serum from a patient with syphilis is added to a specific diagnostic test, hemagglutination occurs. These antibodies circulating in the blood can appear as early as 2 weeks after infection. In this case, we are talking about “rapid response” antibodies, or immunoglobulins of class M. After a month, they are supplemented with specific immunoglobulins of class G. Therefore, at the onset of the disease, this reaction determines only one type of antibodies, indicating an acute infection, and in the secondary and tertiary periods syphilis, it “catches” class G antibodies, of which quite a lot accumulate in the blood. That is why the sensitivity of this reaction at the onset of the disease is somewhat lower, and if a person has been sick with syphilis for several years, then its sensitivity approaches 100% versus 86% in the case of primary, fresh and recent syphilis.

This reaction is highly specific and can be used to confirm or refute the primary diagnosis, which was made using the non-treponemal test. Such non-treponemal tests include RW or the well-known Wasserman reaction. When setting it up, cardiolipin antigen is taken as an antigen, which has nothing to do with the pathogen. It is very similar in structure to syphilitic, but, nevertheless, it is somewhat different from it, and therefore false positive reactions are possible with this type of research.

Therefore, if the patient’s Wasserman reaction is positive, then to confirm or refute the RW results, it is necessary to perform a passive hemagglutination reaction. The specificity of RPHA ranges from 96 to 100%. Even with latent syphilis without any manifestations, she can also make a diagnosis with almost 100% probability.

Since the rules for diagnosing syphilis necessarily require reconfirmation of the primary diagnosis by another method, then if the primary diagnostic method is the RPGA itself, then it also needs to be reconfirmed, despite its high sensitivity, but only using another method. And then the treponemal test is also used, but only a different one, for example, you need to decipher new values ​​using the enzyme-linked immunosorbent assay (ELISA).

Since antibodies belonging to the immunoglobulin G class remain in the blood serum, as a rule, for life, even after active and successful treatment of syphilis with subsequent recovery, these antibodies remain positive. Only in the case when syphilis was suspected and treated in the “very embryo”, a few days after infection, at the stage of formation of chancre and regional lymphadenitis, then RPGA can be negative.

The fact that in both secondary syphilis and tertiary syphilis the RPGA will be equally positive means that such a study cannot be used for differential diagnosis of the stages of the disease. Using RPGA it is also impossible to assess the effectiveness of treatment, since antibodies will still circulate in the blood. The effectiveness of therapy must be assessed using other laboratory tests. Particularly high rates and significant dilution of the patient’s blood serum during RPGA occur in secondary syphilis, as well as in the early and latent form of this disease.

But, despite the high sensitivity and specificity of this test, false positive values ​​are also possible when performing RPGA for syphilis. They occur infrequently, in no more than 2.6% of cases, and appear when antibodies circulate in the patient’s blood that are very similar to syphilitic ones, but are not them. These may be autoantibodies, and most often such “surprises” are thrown up by systemic lupus erythematosus.

Also, those diseases that are caused by other representatives of treponemes, or spirochetes, can lead to false-positive values, for example, Lyme disease, which is caused by Borrelia burgdorferi, a “close relative” of syphilis. You can read about the diagnosis of Lyme disease, or tick-borne borreliosis, here. In some cases, such distortions are caused by oncological pathology, pregnancy, and even sluggish acute myocardial infarction. In the latter case, particles of necrotic cardiac muscle enter the blood, which are similar in structure to cardiolipin antigen; it is used to stage the Wassermann reaction, and is extracted from the heart of cattle.

Also, the cause of false positive results may be cases of intravenous drug addiction, HIV infection and viral hepatitis B and C, leptospirosis and relapsing fever, as well as diseases that occur in hot countries and are caused by treponemes - pinta, yaws, bejel. In rare cases, in patients with low immunity, treponemes, which are saprophytes and live in the oral cavity, may be activated. Also, tuberculosis and infectious mononucleosis can cause such reactions, as in the case of extensive polytrauma and numerous fractures.

Such false-positive reactions must be rechecked after some time; they usually disappear within six months, for example, after resolution of pregnancy or for a longer time.

Based on materials from myanaliz.ru

Advantages of the method

The RPHA reaction is a sensitive diagnostic method. The test helps to detect primary syphilis with up to 86% probability. In the secondary and tertiary stages of the disease, sensitivity increases to 95–100%. The technique also has a number of other advantages:

• To carry out the test, the patient only needs to donate venous blood.
• The study of biomaterial does not take much time. The result is delivered within 24 hours.
• Diagnostics does not require special equipment.
• You can get tested for syphilis for free by receiving a referral from the clinic at your place of registration. In private clinics, the cost of analysis varies from 250 to 1000 rubles.

Preparation

In many clinics, biomaterial collection is carried out strictly in the morning on an empty stomach. After issuing a referral, the doctor will recommend adhering to a number of rules:

• Before donating blood, drink exclusively mineral water without gas in small volumes.
• Avoid eating later than 10–12 hours before visiting the laboratory.
• Stop smoking 2–3 hours before the test.
• Two days before donating venous blood, do not drink alcohol or alcohol-containing drinks.
• Stop taking any medications. If this is not possible, notify your doctor.
• If you feel unwell, you should tell the nurse.

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Decoding the results

The test value can be deciphered by the intensity of bonding, which can be from – to 4+. Understanding these cases gives a clear idea of ​​the presence of antibodies to the infection.

Laboratory screening can be explained as follows:

1. 4+, if there is a uniform mat of cells covering the entire hole.
2. 3+ if most of the well is covered with a uniform mat of cells.
3. A lower density mat surrounded by a small ring (+2) is another positive analysis scenario.
4. The intensity of the mat is reduced and surrounded by a denser ring with a distinctly open center.

If there is a small, clear center and the cells are located at the bottom, the result can be considered negative. The indicators are within the normal range and do not require further investigation. But in the case of an intermediate positive test, MHA-TP and FTA-ABS studies are prescribed.

Normal ranges may vary slightly between laboratories. Some laboratories use different measurements or test different samples. Talk to your doctor about the meaning of the test results.

Positive result

If the RPGA result is positive, it is likely, but not certain, that the disease is present. In this case, the doctor will prescribe a more specific test to confirm the results. A treponemic test is often used to confirm a positive test. It tests whether the immune system has produced antibodies in response to Treponema pallidum, which causes syphilis.

After making a final diagnosis, it is imperative to undergo full treatment. It is necessary to complete a full course of antibiotic treatment, even if symptoms go away. Failure to do so may cause relapse.

Negative result

A negative test is normal. This means that no syphilis antibodies were detected in the blood sample. Normal ranges may vary slightly between laboratories. Some medical centers use different measurements or test different samples. Talk to your doctor about the meaning of the results.

This test may give a false negative result in early and late stage disease. The test must be confirmed by other screenings to make a definitive diagnosis.

About false positives

Antibodies produced as a result of the infection may remain in the body even after the virus has been treated. In some cases, the body may not produce antibodies even if a person is infected with syphilis. This means that the analysis will be inaccurate.

The following conditions may cause false positive results:

1. HIV.
2. Lyme disease.
3. Malaria.
4. Pneumonia (certain types only).
5. Systemic lupus erythematosus.
6. Intravenous drug use.
7. Tuberculosis.

The RPHA test is not perfect, but it is a reliable test that can be the first step in helping determine whether a person is infected. In a blood test, syphilis can be detected as early as 1-2 weeks after infection. The greatest accuracy can be expected within three months, and non-accurate results are possible any time during the first 90 days after infection.

People who have suffered from a syphilis infection in the past may also have a false positive result due to antibodies lingering in the blood. If RPHA testing returns a negative result 90 days or later after exposure, infection is considered absent.

Other diseases such as yaws and yaws (two other types of skin diseases) can also result in a positive FTA-ABS. Sometimes there can be a false positive result, most often in women with lupus.

How is the analysis carried out?

Blood is drawn in a clinic or in a hospital setting. The procedure consists of several stages:

1. The laboratory assistant prepares and labels the test tubes.
2. The patient takes a sitting position and rolls up his sleeve.
3. An oilcloth cushion is placed under the elbow.
4. A tourniquet is applied in the area of ​​the middle third of the shoulder.
5. The laboratory technician asks the patient to clench and unclench his fist several times. This will ensure that the vein is filled with blood.
6. The elbow bend is treated several times with a disinfectant solution. The cotton wool is changed every time.
7. A laboratory worker inserts a needle into the most blood-filled vein.
8. The required amount of biomaterial is drawn into the syringe.
9. The tourniquet comes undone. A cotton swab soaked in alcohol is applied to the puncture site.
10. The needle is carefully removed from the vein.
11. To stop the bleeding, the patient is advised to bend the elbow for 1-2 minutes.

The resulting biomaterial is delivered to the laboratory. A special serum with antibodies to the causative agent of syphilis is added to the blood and the process of agglutination (gluing) of red blood cells is monitored under a microscope. The RPGA result is ready 30 minutes after the analysis. In some cases, the procedure may take 2 to 4 days.

Decoding the RPGA blood test

The result of the diagnostic study is presented in the form of antibody titer. It is entered on the referral form and can have 3 possible values:

• 0.9 – 1.1 – doubtful, re-diagnosis is recommended after 10–14 days;
• >1.2 – the result is positive.

The passive hemagglutination reaction will be negative if the test was scheduled too early. Antibodies to the pathogen begin to be produced only 2-4 weeks after infection. In patients who have previously had syphilis, RPGA will always be positive, so the diagnosis is not used to track the dynamics of treatment.

In approximately 2.5% of cases, laboratory data are false positive. Low titer levels are possible immediately after vaccination and in the presence of:

• systemic connective tissue diseases;
• acute myocardial infarction;
• pregnancy;
• menses;
• weakened immunity;
• hepatitis of various forms;
• oncology;
• infectious diseases - ARVI, influenza, smallpox.

How RPGA blood test stands for, purpose and preparation for analysis

One of the most important blood tests for the body is the RPHA test. It can be used to determine the presence of pathogens such as syphilis in the body. This analysis is recognized as one of the most reliable ways to determine if the body is affected by syphilis. Let's get to know him in more detail.

How does RPGA stand for?

Decoding the RPGA blood test

The abbreviation RPHA refers to a special reaction that reveals passive hemagglutination in the body. Using this reaction, you can detect the process of agglutination of red blood cells in the body. Moreover, during this process, the presence of treponema pallidum antigens is revealed on the surface layers of many of them. This organism is the causative agent of syphilis.

Once in the body of a healthy person, Treponema pallidum provokes the development of an immune response. During this process, the body produces non-specific or non-treponemal and specific or treponemal types of antibodies.

The presence of Treponema pallidum antibodies in the donated blood sample is a thorough confirmation of syphilis in the laboratory.

All serological tests carried out in the laboratory are divided into two groups:

1. Specific type of study (treponemal);
2. Nonspecific type of study (non-treponemal).

The division of studies into these groups is based on the type of antibodies that are detected in the donated blood sample when analyzed for RPHA. Determination of the passive hemagglutination reaction or RPHA is a specific type of research in relation to the causative agent of syphilis.

The reaction occurs in the presence of antitreponemal antibodies. This reaction was first practiced by one of the scientists in 1965 and immediately gained wide recognition among colleagues and patients.

Today, using this method, such a disease of the human body as syphilis is successfully diagnosed.

And the methodology for determining it belongs to the category of specific (treponemal) tests.

Using this highly sensitive diagnostic method, the presence of any stage of syphilis in the body is easily determined:

1. Primary
2. Latent
3. Secondary
4. Tertiary

More information about syphilis can be found in the video.

When donating blood for RPGA, data from microprecipitation reactions are confirmed with an accuracy of the smallest fractions. RPGA allows you to identify false-positive cases of disease development obtained during screening tests.

In some cases, the RPGA method can provoke a false positive result in the patient.

This happens if a person has developed autoimmune diseases. If the human body is affected by a certain group of viral diseases, during the development of which the patient’s number of nonspecific antibodies increases, the RPGA data may also be false. The reason for this is the use of sensitized red blood cells by this method.

When is it necessary to donate blood for RPGA?

Prescribing a blood test for RPGA

An RPGA analysis is prescribed to a patient if there is a suspicion of the development of any stages of syphilis in his body. In addition, this analysis is necessary for certain categories of women before planning pregnancy. It is in the early stages that the detection of this disease will allow you to prescribe appropriate treatment and plan pregnancy, with the goal of giving birth to a healthy baby.

Blood donation to determine syphilis in the body is also prescribed when preparing the patient for the scheduled operation. It is in this case that a successful outcome of surgical intervention in the body is possible. Also, confirmation of the presence of syphilis pathogens in the body will allow doctors to plan the course of the upcoming operation in such a way that the expected therapeutic effect is maximum.

Determination of syphilis agents in the blood by the RPGA method is also important for testing donors before donating blood.

Thanks to RPHA, in this case it is possible to prevent hundreds of cases of infection of recipients with the blood of patients with syphilis. At the same time, there are many cases where people come to blood donation centers as donors, and after donating it to the RPGA, they find out that they have syphilis.

Obtaining results from analysis on RPGA

After the patient donates blood to determine the causative agents of syphilis in his body, some time passes and the results become known. Usually, RPGA gives a positive indicator after four weeks following the initial infection.

In many cases, the primary stage of the disease is characterized by reduced rates; its data are as follows: less than 1:320. The secondary stage of syphilis is accompanied by an increase in titration readings: slightly more than 1:320. Latent syphilis again gives low titres.

Having completed the prescribed course of treatment for the established stage of syphilis, a blood test for RPHA in this patient still shows a positive result.

And this is not an isolated case, but a widespread one and is confirmed throughout life in this category of people.

Preparation and analysis procedure itself

Procedure for donating blood to RPHA

Before donating blood for the presence of causative agents of a disease such as syphilis, it is necessary to prepare properly.

After all, it is precisely the distortion of the data of such an important analysis that can cause the patient to be prescribed the wrong treatment, and this, as we know, can cause the development of other pathologies in the body.

Preparation for this analysis is quite simple:

1. To begin with, you should refuse any food intake before donating blood for RPGA. In other words, you should come for analysis on an empty stomach.
2. It is also not advisable to consume a significant amount of liquids before donating blood for RPGA. The components of the drinks taken by the patient may also affect the results of this analysis.
3. It is best to take this test in the first half of the day, since it will be quite difficult for you to go without food and water throughout the day.
4. Before testing for RPHA, the patient is advised to refrain from smoking for thirty minutes. Substances contained in tobacco smoke can distort the reliability of the results of this analysis.
5. Drinking alcohol before donating blood is also strictly prohibited.

Read: Complete blood count - platelets: diagnosis and interpretation

When you come to the appropriate office for analysis, you need to free your arm above the elbow from clothing. Blood for this analysis is taken from the area of ​​the ulnar vein.

In some cases (when the veins lie quite deep in a given place), blood is taken from venous vessels located on the hand or in the forearm area.

The procedure for taking a blood sample is quite simple and almost painless. After the procedure, the laboratory specialist will definitely set a time when you can come for the finished results.

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Source: https://DiagnozLab.com/analysis/clinical-tests/blood/kak-rasshifrovyvaetsya-rpga-analiz-krovi-naznachenie-i-podgotovka-k-analizu.html