In the article, consider what it is - PCR diagnostics? Human papillomavirus (HPV) today is a very common disease that occurs in a chronic form and is fraught with frequent relapses. Polymerase chain reaction (PCR) is the most modern method for diagnosing papillomavirus. This method is considered very reliable and helps to identify not only the presence of this virus in the human body, but also its quantity and variety. PCR analysis for HPV is sensitive even to inactive forms of the virus, in which there are no external manifestations in the form of genital warts and papillomas.
What is the method based on?
Based on the study of the patient's DNA in order to detect the presence of foreign components in this chain. It consists of four nucleotides, which are arranged in a specific sequence. If a virus enters the body, there is a change in the order in this chain, which allows you to carefully monitor the activity of even the most insignificant foreign particles. The HPV PCR research technique is carried out using viral particles, which determines the rate of cell division.
What defines research?
This diagnostic principle allows you to track HPV activity not only while it is in a passive state, but also during the incubation period. PCR diagnostics determines:
- presence of HPV in the body;
- strains that infect the patient;
- quantitative content in the body.
Papillomavirus infected most people, but a strong immune defense suppresses its manifestations and does not allow to multiply. Thus, the detection of HPV in a qualitative way cannot always be justified, since it is not rational if viral particles are present in the body, but their impact is so minimal that it does not harm a person in any way. Qualitative analysis shows a positive result, and this often confuses a person.
Quantitative method
Therefore, a quantitative method is most often used for diagnosis, which allows you to track the number of viral agents in the body and determine how dangerous their activity is. In addition, it is important to establish the variety of HPV strains. They are divided according to the degree of oncogenicity: some can become the main factor in the occurrence of oncological diseases, while others are absolutely safe and can cause only some cosmetic problems.
Each individual situation requires an individual approach,therefore, before undergoing this laboratory test, it is advisable to consult a qualified specialist who will tell you how and for which strains it would be best to test, taking into account the patient's condition and clinical symptoms.
Indications for conduction
The most significant reason to undergo a PCR test for HPV is the presence of warts on the body.
Infection with this virus is possible only from a person. After penetration into the bloodstream, the pathogenic microorganism begins to multiply in the upper layers of the skin, which leads to the development of characteristic manifestations - the formation of condylomas or papillomas. Since this disease is quite common and occurs in almost 80% of the population, the likelihood of contracting it is extremely high. Papillomaviruses are transmitted through:
- unprotected intercourse;
- while kissing;
- when giving birth to a child from mom;
- in a household way;
- with close skin contact.
The main indications for a blood test and a PCR smear for HPV are skin symptoms of this disease, which look like hanging warts on a thread-like thin stalk. Even if such condylomas are not observed on the skin, the virus may still be present in the blood, but its course will be asymptomatic. If a patient is diagnosed with papillomavirus infections of the 18th and 16th subtypes, it is recommended that he be regularly checked by specialists such as a gynecologist and urologist, undergo diagnostic procedures and be tested for HPV, becauseonly through timely diagnosis is it possible to prevent the development of certain cancers.
Types of techniques
As part of the PCR diagnostics for HPV, four main testing methods have been developed, each of which has some specific features and is prescribed taking into account the condition of the sick person. Expert advice is required to select the best method. So, four methods:
- A qualitative method that is used to refute or confirm the presence of a virus in the body. Its main disadvantage is the inability to establish the type of HPV strain (only 14-21 types). Most often, a qualitative method is used simultaneously with other methods for detecting papillomavirus. The result is reported using two ratings: "not found" or "detected". That is, this technique either states the presence of foreign DNA, or indicates its absence.
- Genotyping is a method that can determine the presence of a virus in the human body and establish its variety. This method is used in cases where it is necessary to establish whether the DNA of the virus remains after the treatment or a relapse is observed as a result of a new infection. Genotyping helps to evaluate the effectiveness of the therapy by determining the type of HPV. If this is the same strain that the patient was treated for, then the treatment was unsuccessful. If the analysis shows the presence of another type of HPV, one can indicatereinfection.
- Combined method, which is a highly specialized diagnostic method based on a combination of qualitative and 16 strain detection using genotyping. The result can be represented by 3 answers: “strain 16 detected”, “not detected” and “HPV type 16 inclusive detected”. This method is used when you suspect the presence of a type of papillomavirus that can cause cervical cancer in women.
- Quantitative PCR method for HPV of high oncogenic risk, which allows you to determine the level of the virus in the blood and track its development. It is considered the most informative, since it allows you to determine the severity of the pathological process, on the basis of which the correct treatment is selected. The technique is based on determining the number of virus cells within the studied 100 thousand. If their total is above 5, this indicates a high concentration of papillomavirus in the body, which increases the likelihood of cancer cells. If the amount is less than 3, the concentration is considered negligible.
How to prepare and take the test?
Blood can be taken as a biomaterial for HPV, but secretions from the urethra in men and the cervix in women are most often taken.
Special preparation for PCR for HPV is not required. The main condition is not to urinate a few hours before the procedure. In addition, it is advisable not to have sexual intercourse 2-3 days before the study and nottake alcoholic drinks. At the same time, do not forget about intimate hygiene procedures.
For men
Men take a swab - the head of the penis and the urethra are treated with saline. The specialist uses a special brush, which is inserted into the urethra by about 4 cm. Biological material is collected with a slight rotation, placed in a test tube and sent to the laboratory for research. At the same time, you can store it for no more than 2 days from the moment of collection.
Women
Smearing for PCR analysis for HPV in women is performed as follows: a sterile solution is applied to the cervix, then a swab is taken from the cervical canal with a brush. The device is inserted to a depth of approximately 1 cm, after which the doctor makes a scraping from the canal walls with rotational movements. Biological material is placed in a special test tube, where it stays for about 15 seconds. In it, the specialist wipes it against the walls, and then takes it out. Next, the contents of the test tube are sent for laboratory testing.
Proper sampling of material for research is the key to successful diagnosis and obtaining a reliable result. If at the same time sterility is violated, and foreign microorganisms penetrate into the test tube, during the analysis, a virus may be recognized, which in fact is not in the patient's body. An error can also occur due to the small amount of material taken for research.
Where to take PCR for HPV, many people are interested. Tests can be done in any medicalclinic or laboratory, for example, in "Invitro" or "Hemotest".
Method advantages
PCR is one of the main diagnostic methods and at the moment remains the most popular among doctors. This study is carried out not only to detect HPV, but also allows you to detect other pathological microorganisms that can be transmitted through sexual contact. Such an analysis helps to diagnose hidden infections, hepatitis, etc. The PCR test for HPV has a number of advantages over other methods for detecting diseases. These benefits are:
- High specificity. The analysis helps to separate traces of foreign DNA with a high probability when studying the collected biomaterial.
- High performance. The PCR study is an automated process that helps to conduct the study directly on the day of the analysis. This speed allows a person not to worry about the results for a long time and get it on hand in a few days.
- High sensitivity. Testing makes it possible to investigate the activity of viruses even during the incubation period, when their concentrations are very low. This helps to prevent the occurrence of a pathological process and start timely therapy.
- Possibility of carrying out several analyzes at once. Based on a single blood sample taken, diagnostics can be carried out to determine several diseases at once. For example, you can simultaneouslyto identify the causative agent of gonorrhea and chlamydia. At the same time, this procedure will not be able to negatively affect the reliability of the result.
Flaws of the study
Despite the great popularity and information content of this analysis, there are some negative aspects of PCR diagnostics for HPV. Chief among these is the likelihood of false positive results. This happens when the therapy has already been carried out, the infection has been destroyed, but dead virus cells still remain in the tissues of the body. Cell renewal takes some time. If you conduct a study earlier than 2-3 months after treatment, PCR may show a positive result. The technique does not notice any differences, since it is aimed at searching for viral DNA, which can be found even in already dead cells. This contributes to false positive results. This situation can be avoided if a laboratory test is carried out within the time frame set by the attending physician.
Transcript
What will PCR decryption for HPV show?
The doctor should interpret the test results. But it is also important for the patient to be aware of the structure of the results sheet. If the analysis indicates “DNA not detected”, then there is no papillomavirus in the blood. If the Lg indicator is 5 or more, this indicates its high concentration in the blood, Lg 3-5 - a significant amount, less than 3 - an insignificant amount.
False negative analysis
Also,false-negative analysis may occur. It occurs if:
- biological material collected was improperly stored or transported;
- sterile conditions were violated, and other microorganisms got into the received blood of the patient;
- due to unsuitability of reagents.
To eliminate the possibility of false negative results, it is necessary to select an approved laboratory with highly qualified personnel for this analysis.
We examined in detail how and why PCR diagnostics are carried out. What it is is now clear.
