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Screening testing what. Nine Essential Medical Screening Tests for Men


SCREENING- In 1951, the US Commission on Chronic Diseases defined screening as: “The presumptive identification of an unrecognized disease or defect by means of tests, examinations, or other easily applied procedures.”
Screening tests can distinguish between apparently healthy people those who are likely to have the disease and those who are likely not to have it. The screening test is not intended to be diagnostic. Individuals with positive or suspicious results should be referred to their physicians for diagnosis and appropriate treatment." The initiative to conduct screening usually comes from the researcher, person or organization that provides medical care, and not from the patient with complaints. Typically, screening is aimed at chronic diseases and to identify a disease for which medical care is not yet available. Screening allows you to identify risk factors, genetic predispositions and precursors or early manifestations of the disease. There are different types of medical screening, each with its own focus.

Types of screening


  • Mass screening(Mass S.) simply means screening the entire population.
  • Complex or multidimensional screening(Multiple or multiphasic S.) involves the use of various screening tests at the same time.
  • Preventive screening(Prescriptive S.) is aimed at the early detection of diseases in apparently healthy people, the control of which may be more successful if detected at an early stage. Example: Mammography to detect breast cancer. Characteristics of a screening test include accuracy, estimated number of cases detected, accuracy, precision, sensitivity, specificity, and validity. (See also: detectable preclinical period, measurements.)
  • Selective screening- carried out in the absence of symptoms, but in the presence of one or more risk factors for developing the disease being sought, for example, indications of diseases in immediate relatives, lifestyle characteristics, or the subject’s belonging to a population with a high prevalence of the corresponding disease
  • Genetic screening(GENETIC SCREENING) - the use of molecular biology methods to identify mutations that are present in humans and increase the risk of developing a disease, for example, the BRCA1 and BRCA2 genes, which significantly increase the risk of developing breast and ovarian cancer in women. Genetic screening may raise ethical issues, such as notifying people that they are at increased risk for a disease for which there is no effective treatment. Problems may also arise if the diagnostic result could lead to problems with employment and insurance.
  • Systematic (sample-free) screening– carried out to all individuals in a certain population, for example, ultrasound screening of chromosomal pathology, which is carried out in the first trimester of pregnancy. The population for this screening is all pregnant women without exception.
  • Selective screening– carried out among persons exposed to certain risk factors that can cause a particular disease. An example of such screening is the study of medical workers for the incidence of hepatitis B and C, HIV, syphilis, because representatives of these professions come into contact with biological fluids of potentially sick people and, accordingly, have an increased risk of contracting these infectious diseases.

Terms and concepts characterizing screening


  • Screening level(SCREENING LEVEL) - the limit of the “norm” or the separation point beyond which the screening test is considered positive.
  • Sensitivity and Specificity
  • Prognostic value of a diagnostic test
  • Likelihood ratio
  • False positive results
  • False Negatives

Screening criteria


Below are the screening criteria proposed by the UK NATIONAL SCREENING COMMITTEE:
Screenable disease or condition
  • The disease or condition being screened has a significant impact on the patient's health;
  • The etiology and pathogenesis of the disease must be carefully studied, risk factors for the development of the disease and its signs must be known, which can be identified in the latent or early stages of its development;
  • All effective measures aimed at preventing the development of the disease must be applied;
  • It is necessary to take into account the possible ethical and psychological consequences of screening for individuals who are carriers of a gene mutation when screening for gene diseases with a recessive mode of inheritance.
Screening test
  • Must be simple to implement, safe for the patient’s health, accurate and reliable;
  • The normal distribution of test values ​​in the population being examined must be known, and an acceptable threshold level for test values ​​at which the screening result will be considered positive must be established;
  • the test must be acceptable to the population being tested;
  • Screening for gene-related diseases should be carried out only for those diseases for which it is possible to diagnose all possible gene mutations that cause the disease. If it is not possible to diagnose all gene mutations, screening for a given gene disease should not be performed.
Treatment
  • If the disease is diagnosed at an early stage, there must be an effective treatment.
  • Effectiveness on disease outcomes when diagnosed and treated early must be demonstrated in clinical trials
  • Before introducing a screening program into clinical practice, it is necessary to clearly organize the actions of all health care institutions involved in screening and treatment of this disease.
Screening program
The developed screening program must meet a number of requirements:
  • The effectiveness of the screening program should be confirmed in the framework of RCTs. Main criteria: reduction in morbidity and mortality from the disease being screened.
  • Evidence of the accuracy of the screening test to detect the disease under study.
  • Proposed screening studies must be clinically acceptable and ethical
  • The benefits of screening must outweigh the potential physical and psychological harm that the patient may experience as a result of participating in the screening program.
  • Economic feasibility: the cost of screening should not exceed the costs of diagnosing and treating the disease if it is detected at a later date.
  • Constant quality control of the current program
  • Before implementing a screening program, you should ensure that there is sufficient equipment and specialists to implement it.
  • Patients should be informed about the possible results of the screening. Information must be conveyed in a language that the patient understands.
  • Screening for the detection of gene diseases with a recessive type of inheritance should be acceptable for carriers of the recessive gene and its relatives.

Methods for assessing people's health are divided into:

    diagnostic ( clinical) tests;

    screening tests.

Diagnostic tests - intended for making a clinical diagnosis of already sick people (who have consulted a doctor) people.

Main requirement The requirement for diagnostic tests is accuracy, and for this they must be:

    reliable ( valid).

    reproducible;

Test sensitivity

Sensitivity ( sensitivity ) test is its ability to give a reliable assessment presence of this disease in the person being examined

Specificity of the test.

Specificity ( specificity ) test is its ability to give a reliable assessment absence of this disease in an individual. Usually in this case they say that the person is healthy, meaning by this the absence of a certain disease.

Reproducibility (repeatability) test - this is his ability the same measure any phenomena, processes, states in the series repeated measurements. Absolutely identical assessments of any health parameters are relatively rare during repeated examinations. Reasons ( differences in variability) indicators are related to the true ( objective, biological) and with subjective variability.

True variability results is related to the peculiarities of the life process of the organism of the subject. It is known that even in healthy individuals, many indicators vary over a short period of time between studies.

Subjective variability due to personnel errors or test errors ( technology).

Validity of the test.

The sensitivity, specificity and reproducibility of a test determine its reliability or validity ( validity ).

Credibility or validity separate test means:

    the ability of the test to provide a true assessment of those parameters of the individual's body or environment that need to be measured;

    correspondence of individual test data to objective symptoms of the disease and medical history;

    consistency of data from one test with data from traditional laboratory tests.

Screening

Screening ( screening, screening) , - examination ( most often - massive) persons, consider themselves healthy , in order to identify a previously unrecognized disease in them. Screening is also used to identify risk factors in healthy individuals,

Screening is carried out using screening tests, which, like any tests, can be carried out: in the form of a survey, physical examination ( for example, examination of the skin, palpation of individual organs, etc.), laboratory research and other methods.

Despite the commonality of the goal, it is necessary to distinguish:

    screening as preventive measure , and in this case it is not relevant to the conduct of epidemiological studies

    screening as a method used in epidemiological studies.

Depending on the number of persons examined, on their professional or other individual characteristics, depending on the set of screening tests used, distinguish:

    mass screening – for example, screening the entire population of settlements, or screening large samples;

    targeted screening – health assessment individual contingents, identified by individual characteristics, such as gender, age, race, profession, social status, etc., or the population identified on the basis of past exposure to an environmental risk factor;

    multidisciplinary screening – assessment of health using a set of screening tests to identify several diseases;

    search screening , – examination with screening tests of persons already having a known pathology to identify another disease .

Screening test requirements:

    sensitivity, specificity and reproducibility;

    validity;

    ease of execution and low cost;

    safety;

    acceptability for the person being examined;

    effectiveness (as a preventive measure).

20-21 Evidence-based medicine is a branch of medicine based on evidence, involving the search, comparison, synthesis and wide dissemination of evidence obtained for use in the interests of patients (Evidence Based Medicine Working Group, 1993). Evidence-based medicine is a new approach, direction or technology for collecting, analyzing, summarizing and interpreting scientific information. Provides for the conscientious, explanatory, and common sense use of the best current advances in the care of each patient.

Reliable fact is reliable and objective evidence of a principle or procedure. When considering the results of a study as a reliable fact, special attention must be paid to the quality of the study, which largely depends on a predetermined plan and research design.

Correct scheme The (design) of the study allows for bias to be minimized and objective results to be obtained. The main emphasis is not on intuition or generally accepted practice, but on an impartial, objective assessment of a scientific fact.

In this regard, it is of great importance standards quality of information and its critical assessment.

AREA OF APPLICATION

The principles of evidence-based medicine allow us to develop the most effective, safe and cost-effective modern therapeutic strategies.

    determination of the tasks facing the doctor;

    description of the disease (etiology, prevalence, clinical picture, etc.);

    algorithms for diagnostic procedures (examination program, indications and contraindications for prescribing diagnostic procedures);

    treatment (tactics, description of specific drugs and treatment measures, criteria for effectiveness and termination of treatment);

    complications, prognosis, indications for hospitalization, clinical observation, etc.

Implementation of standardization systems in healthcare :

    scope of drug circulation;

    development and application of medical equipment;

    development of a formulary system (protocols for the management and treatment of patients);

    development and use of protocols in insurance medicine;

    determining the relative value of various sources of information in relation to the search for answers to clinical questions.

Prenatal (from Latin prenatal) screening is a widely used method that is carried out at certain stages of pregnancy to determine the risks of serious genetic abnormalities.

The word “screening” literally means “sifting”: it allows, based on a number of signs, to identify a group of women in a large mass of pregnant patients who need more careful monitoring and additional tests.

It is carried out three times, according to Order of the Ministry of Health of the Russian Federation of November 1, 2012 N 572n “On approval of the Procedure for providing medical care in the field of obstetrics and gynecology”: for pregnancy periods of 11-14, 18-21 and 30-34 weeks.

At a gestational age of 11-14 weeks, a comprehensive prenatal diagnosis of child development disorders is carried out, including the determination of maternal serum markers, followed by a comprehensive software calculation of the individual risk of having a child with a chromosomal pathology.

Prenatal diagnosis and ultrasound at 18-21 weeks makes it possible to exclude late-manifesting congenital anomalies of fetal development.

At 30-34 weeks of pregnancy, an ultrasound is performed.

Prenatal diagnosis includes:

  • Complexes of biochemical blood tests to identify markers of a certain pathology in the fetus (performed in the first and second trimesters).
  • Ultrasound examinations (during pregnancy proceeding as usual, a woman attends up to 3-4 scheduled ultrasound examinations during the entire period).

There is also invasive And non-invasive prenatal diagnosis

Invasive prenatal diagnosis carried out when a high risk of fetal pathology is identified based on screening results. Such tests (cordocentesis, amnicentesis, chorionic villus biopsy) are unsafe for the fetus and are carried out only for serious indications.

Non-invasive prenatal diagnostics (NIPT - non-invasive prenatal test) is a safe and accurate method. The analysis includes the determination of freely circulating extracellular DNA, and the accuracy of the method reaches 99.9%.

A recommendation to undergo prenatal screening does not mean that the fetus will certainly show undesirable signs. However, if pathology cannot be excluded, the patient will be referred to a geneticist to determine further steps.



Who should prenatal screening be indicated for?

Biochemical and ultrasound prenatal diagnostics are recommended for all pregnant women. The data obtained as a result of screenings allows us to identify groups at risk of pregnancy complications and the risk of congenital defects in the fetus.

At the same time, the classification of a woman and fetus, based on the results of prenatal screening, into a risk group for any pathology does not mean at all that this complication will inevitably develop. It would be more correct to say that the likelihood of developing a certain type of pathology in this patient’s child is higher than in others.

Also at risk automatically include patients:

  • aged 35+ (and/or if the future father is over 40 years old);
  • having genetic abnormalities of fetal development in the family;
  • taking medications that can negatively affect the development of the fetus;
  • exposed to harmful radiation;
  • have had infectious or viral diseases in the first trimester of pregnancy;
  • with a complicated medical history (frozen pregnancy, stillbirth, miscarriage in the past).

What parameters does it take into account? biochemical prenatal screening :

Double test (first trimester screening). It is taken at 10-13 weeks of pregnancy (at later stages the analysis is not carried out as it becomes uninformative).

The study determines:

  • free b-subunit of human chorionic gonadotropin (hCG) is a hormone produced throughout pregnancy and regulates many important processes in fetal development.
  • PAPP-A (pregnancy associated plasma protein A) is a plasma protein A produced by the placenta. Its concentration increases gradually during pregnancy.

Special software allows you to calculate the risks of chromosomal abnormalities in the fetus. Moreover, it is not the concentration indicators of hCG and PAPP-A in the blood of a pregnant woman that are taken into account - the program converts these data into special values ​​called MoM. And from the MoM it is calculated how close or far from the norm the desired indicator is in accordance with the given stage of pregnancy. Normally, MoM values ​​vary from 0.5 to 2. Deviations from these values ​​may indicate genetic defects.

Chromosomal pathologies are recorded in approximately 0.6-1% of newborns. The most common are Down syndrome (occurs in 1 child in 600-700 newborns), Edwards syndrome (1:6500), Patau syndrome (1:7800), Shereshevsky-Turner syndrome (1:3000).

Blood test always done after . Each examination provides its own amount of information about pregnancy and helps the doctor combine the results into the overall picture as accurately as possible.

Triple test . This biochemical diagnosis is carried out at 16-20 weeks of pregnancy (optimally at 16-18 weeks).

It is called a triple test because it determines three indicators:

  • total human chorionic gonadotropin (hCG);
  • estriol is a pregnancy hormone produced by the placenta. During a normal pregnancy, its concentration steadily increases;
  • alpha fetoprotein (AFP) is a protein produced during pregnancy. Its concentration increases as the period increases, then gradually decreases.

Sometimes the study also includes the hormone inhibin A. Its level normally also changes during pregnancy - towards lower concentrations in later stages.

The information content of the triple test is such that it allows 80% to identify malformations of the neural tube (that is, the spine, spinal cord and brain) and a number of genetic defects (Down, Edwards, Klinefelter syndromes).

Based on all the data obtained, the doctor adjusts the pregnancy management tactics, or (in the worst case scenario) the issue of the possibility of prolonging the pregnancy is decided.

Important: you should not interpret the results of prenatal screening yourself, relying on the advice of “experts” from the Internet. Only an experienced specialist who has received special education has the right to interpret research data and decipher data. Pregnancy is not a condition in which self-diagnosis or self-medication is possible!

In the third trimester, prenatal screening includes only ultrasound. All the informative value of standard biochemical tests has already been exhausted by this time.

Non-invasive prenatal DNA test.

Today, another method for determining chromosomal abnormalities has emerged - a non-invasive prenatal DNA test. The study is informative and safe for both the woman and the fetus. You can donate blood for testing after 9 weeks of pregnancy. Unfortunately, this test is still not widely used today and is very expensive.

Our prenatal screening programs

The MedicCity clinic uses internationally recognized programs, thanks to which the majority of incurable genetic defects (Down, Patau, Edwards, Cornelia de Lange, Shereshnevsky-Turner syndromes, pathologies of neural tube development, etc.) are identified at an early stage and in a short time.

Prenatal screening:

  • Prenatal screening of the first trimester of pregnancy, calculation of the risk of fetal chromosomal abnormalities, LifeCycle program (DELFIA)
  • RARR-A
  • Free b-hCG
  • Prenatal screening of the second trimester of pregnancy, calculation of the risk of fetal chromosomal abnormalities, LifeCycle program (DELFIA)
  • Free b-hCG
  • Free estriol
  • Prenatal screening of the first trimester with calculation of the risk of preeclampsia, LifeCycle, Predictor (DELFIA) programs
  • PAPP-A
  • Free b-hCG
  • Prenatal screening of the first trimester of pregnancy, calculation of the risk of fetal chromosomal abnormalities, PRISCA program (IMMULITE)
  • PAPP-A
  • Free b-hCG
  • Calculation of the risk of early and late preeclampsia in the first trimester of pregnancy, Predictor program (DELFIA)
  • PAPP-A
  • Prenatal biochemical screening of the first trimester of pregnancy, without risk calculation (for inclusion in the Astraia program).
  • Determination of biochemical markers PAPP-A, free b-hCG in pregnant women from 9 weeks to 13 weeks 6 days. The study is carried out on a Delfia analyzer (PerkinElmer, USA) in accordance with the recommendations of the FMF (Fetal Medicine Foundation, London).

In our multidisciplinary clinic you can visit specialists in more than 30 areas. We have attentive and experienced doctors, modern, high-precision equipment.

Going through diagnostics at MedicCity means saving time and saving nerve cells!

Screening Test is a simple diagnostic test used to study a large number of people in order to identify individuals with a high probability of having a disease. An example of such a screening test is the Guthrie test and cervical smear. The limited use of a particular screening test depends on the strength and frequency of the disease distribution, as well as on the effectiveness and availability of treatment. Other factors that also need to be considered are safety, ease of use, cost and sensitivity of a particular test. See also Genetic screening.

Source: "Medical Dictionary"


Medical terms. 2000 .

See what “Screening Test” is in other dictionaries:

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