In the article, we will 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 advanced diagnostic technique for 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. An analysis of PCR for HPV is sensitive even to inactive forms of the virus, in which external manifestations in the form of genital warts and papillomas are absent.
What is the method based on?
It is based on a study of the patient’s DNA in order to detect the presence of foreign components in this chain. It consists of four nucleotides that are arranged in a specific sequence. If a virus enters the body, a change in order in this chain is observed, which allows you to carefully track the activity of even the smallest foreign particles. The methodology for studying PCR for HPV is carried out using viral particles, which determines the rate of cell division.
What defines a study?
This diagnostic principle allows you to track the activity of HPV, not only while it is in a passive state, but also in the incubation period. PCR diagnostics determine:
- the presence of HPV in the body;
- strains with which the patient is infected;
- quantitative content in the body.
Most people are infected with the papillomavirus, but a strong immune defense suppresses its manifestations and does not allow it 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 effect is so minimal that it does not harm a person in any way. Qualitative analysis shows a positive result, and this often leads to confusion.
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 establish how dangerous their activity is. In addition, it is important to establish a variety of HPV strains. They are divided according to the degree of oncogenicity: some can become the main factor in the occurrence of cancer, while others are absolutely safe and can cause only some cosmetic problems.
An individual approach is required in each individual situation, therefore, before undergoing this laboratory study, it is advisable to consult a qualified specialist who will tell you which way and which strains will be best checked taking into account the patient's condition and clinical symptoms.
Indications for
The most significant reason for undergoing PCR testing for HPV is the presence of warts on the body.
To get this virus is possible only from a person. After penetration into the blood, the pathogenic microorganism begins to multiply in the upper layers of the skin, which leads to the development of characteristic manifestations - the formation of genital warts or papillomas. Since such a disease is quite common and is observed in almost 80% of the population, the likelihood of them becoming infected is extremely high. Papillomaviruses are transmitted by:
- unprotected intercourse;
- during a kiss;
- during childbirth from a mother;
- household way;
- with close contact of the skin.
The main indications for conducting a blood test and a PCR smear for HPV are the skin symptoms of this disease, which look like hanging warts on a filamentous thin leg. Even if such condylomas are not observed on the skin, the virus may be present in the blood anyway, but its course will be asymptomatic. If a patient is found to have papillomavirus infections of the 18th and 16th subtypes, he is advised to be regularly checked by specialists such as a gynecologist and a urologist, undergo diagnostic procedures and be tested for HPV, because only due to timely diagnosis is it possible to prevent the development of some oncological diseases.
Types of techniques
As part of the PCR diagnostics for HPV, four basic testing methods have been developed, each of which has some features of the test and is prescribed taking into account the condition of a sick person. A specialist consultation is required to select the best method. So, there are four methods:
- A high-quality method that is used to refute or confirm the presence of a virus in the body. Its main disadvantage is the inability to establish a variety of the HPV strain (only 14-21 types). Most often, a qualitative method is used simultaneously with other methods for detecting papillomavirus. The result is transmitted using two ratings: “not detected” or “detected”. That is, this technique either states the fact of the presence of someone else's DNA, or indicates its absence.
- Genotyping is a method that is able to determine the presence of a virus in the human body and establish its type. This method is used in cases where it is necessary to establish whether the DNA of the virus remains after the treatment or if there is a relapse as a result of repeated new infection. Genotyping helps to evaluate the effectiveness of the therapy by determining the type of HPV. If this is the same strain from which the patient was treated, then the treatment was unsuccessful. If the analysis shows the presence of another type of HPV, you can indicate re-infection.
- The combined method, which is a highly specialized diagnostic method based on a combination of qualitative and determination of 16 strains using genotyping. The result can be represented by 3 answers: “16 strains were detected”, “not detected” and “HPV detected with type 16 inclusive”. This method is used if there is a suspicion of the presence of a type of papillomavirus that can cause cervical cancer in women.
- A quantitative PCR method for HPV of high oncogenic risk, which allows you to establish the level of the virus in the blood and track its development. He is considered the most informative, since it allows you to determine the severity of the pathological process, based on which the correct treatment is selected. The technique is based on determining the number of virus cells within the studied 100 thousand. If their combination is above 5, this indicates a high concentration in the body of papillomavirus, which increases the likelihood of cancer cells. If the amount is less than 3, the concentration is considered insignificant.
How to prepare and take the analysis?
HPV can take blood as a biomaterial, however, most often, urethral secretions in men and cervix in women are taken.
Special preparation for PCR at 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 not to take alcoholic beverages. At the same time, do not forget about intimate hygiene procedures.
In men
In men, a smear is taken - the head of the penis and the urethra are treated with saline. The specialist uses a special brush, which is inserted about 4 cm into the urethra. Using gentle rotation, the biological material is collected, placed in a test tube and sent to the laboratory for examination. At the same time, it can be stored for no more than 2 days from the date of collection.
Among women
Taking a smear for PCR analysis for HPV in women is as follows: a sterile solution is applied to the cervix, then a smear is taken using a brush from the cervical canal. The device is injected to a depth of approximately 1 cm, after which the doctor scrapes from the walls of the channel with rotational movements. Biological material is placed in a special test tube, where it is located for about 15 seconds. In it, a specialist wipes it on the walls, and then takes it out. Next, the contents of the tube are sent for laboratory testing.
The correct selection of material for research is the key to successful diagnosis and obtaining reliable results. If sterility is violated in this case and foreign microorganisms enter the test tube, the analysis may recognize a virus that is not actually present in the patient’s body. Mistakes can also happen due to the small amount of material taken for research.
Where to pass PCR to HPV is interesting to many. Analyzes can be done in any medical clinic or laboratory, for example, in Invitro or Hemotest.
Method Advantages
PCR is one of the main diagnostic methods and today remains the most demanded among doctors. This study is conducted 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 latent infections, hepatitis, etc. An HPV PCR test has several advantages over other methods for detecting diseases. These benefits include:
- High specificity. The analysis helps with a high probability to separate traces of foreign DNA when studying the collected biomaterial.
- High performance. PCR testing is an automated process that helps to conduct a study directly on the day of 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 allows you to study the activity of viruses even in the incubation period, when their concentrations are very low. This helps to prevent the occurrence of the pathological process and begin timely therapy.
- The ability to conduct several analyzes at once. Based on one blood sample taken, a diagnosis can be made to determine several diseases at once. For example, at the same time it is possible to identify the causative agent of gonorrhea and chlamydia. However, this procedure will not be able to negatively affect the reliability of the result.
Study disadvantages
Despite the great popularity and informativeness of this analysis, there are some negative aspects of PCR diagnostics for HPV. The main one is the probability of obtaining false positive results. This happens when the therapy has already been carried out, the infection is destroyed, but dead virus cells still remain in the tissues of the body. Cell renewal takes some time. If you conduct the study earlier than 2-3 months after treatment, PCR may show a positive result. The method 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. You can avoid this situation if you conduct a laboratory test within the time frame set by your doctor.
Decryption
What will the decoding of PCR on HPV show?
The doctor should interpret the results of the tests. But the patient is also important to know about the structure of the results form. If the analysis says “no DNA was found,” then papillomavirus is not in the blood. If the indicator Lg 5 and more, this indicates its high concentration in the blood, Lg 3−5 - a significant amount, less than 3 - a slight.
False Negative Analysis
In addition, a false negative analysis may be observed. It occurs if:
- the collected biological material was improperly stored or transported;
- sterility conditions were violated, and other microorganisms entered the patient’s blood;
- due to unsuitability of reagents.
To exclude the possibility of obtaining false negative results, it is necessary to select a proven laboratory with highly qualified personnel for this analysis.
We examined in detail how and why PCR diagnostics are performed. What it is is now clear.