Normal duration of bleeding. What is the normal blood clotting time and bleeding duration? What does a change in the norm of red blood cells indicate?

Principle. The duration of bleeding from the capillaries after puncturing the skin with a scarifier is determined.

Progress. The determination can be made by pricking a finger or earlobe. The depth of the puncture should be at least 3 mm - only under this condition the blood will be released from the wound spontaneously, without pressure. Immediately after the puncture, start the stopwatch. The first drop of blood is not removed with cotton wool, as usual, but is touched with filter paper, which absorbs the blood. Next, remove any protruding drops of blood with filter paper every 30 seconds. Gradually the drops of blood become smaller. When traces of blood no longer remain, the stopwatch is turned off.

Sources of errors: insufficiently deep puncture, hasty removal of drops of blood, touching the skin with filter paper, which helps stop bleeding.

Normal values . The duration of bleeding according to Duque is 2-4 minutes.

Diagnostic value . Of practical importance is the prolongation of bleeding time, which is observed in thrombocytopenia, liver diseases, vitamin C deficiency, malignant tumors, etc. In hemophilia, this test remains within normal limits.

Determination of capillary blood clotting time (according to Sukharev)

Principle. The time of formation of a blood clot in the Panchenkov capillary is determined.

Progress . The skin is pierced and the first drop of blood is removed. Draw blood by gravity into a clean, dry Panchenkov capillary up to the “70-75” mark (25-30 divisions) without air bubbles and turn on the stopwatch. By tilting the capillary, the blood is moved to the middle of the tube. Every 30 seconds, tilt the capillary alternately to the right and left at an angle of 45 degrees. In this case, the capillary must be held tightly in the hand in order to maintain a higher and constant temperature clotting blood. At the beginning of the study, blood moves freely inside the capillary, and then its movement slows down and a “tail” of fibrin threads appears - this indicates the beginning of blood clotting. When clotting is complete, the blood stops moving. The moments of the beginning and end of blood coagulation are recorded using a stopwatch.

Normal values . Start of coagulation: 30 seconds - 2 minutes; end of coagulation: 3-5 minutes.

Diagnostic value . Prolongation of blood clotting time is observed with severe deficiency of factors involved in the internal pathway of prothrombinase formation, deficiency of prothrombin and fibrinogen, as well as with an overdose of heparin.

8.4. CHECK QUESTIONS ON THE TOPIC “HEMORRHAGIC DIATHESES”

1. What does the term “Hemorrhagic diathesis” mean?

2. What groups are they divided into? hemorrhagic diathesis?

3. How it is carried out laboratory diagnostics thrombocytopenia, thrombocytopathy, coagulopathy, vasopathy?

4. Morphology of platelets.

5. Functions of platelets.

6. Methods for counting the number of platelets in the blood.

7. Normal quantity platelets in the blood.

8. Causes of thrombocytopenia and thrombocytosis.

9. What mechanism of hemostasis characterizes the duration of bleeding and the clotting time of capillary blood?

10. Duration of bleeding is normal and with various types hemorrhagic diathesis.

11. Clotting time of capillary blood is normal and with thrombocytopenia, coagulopathy, vasopathy.

GROUPS AND RH BLOOD Affiliation

On the surface of human blood cells there are a large number of structures that are classified as antigens, that is, when they enter the body of another person, they stimulate the production of antibodies. They are also called isoantigens [from the Greek. isos is the same], since they are found in representatives of the same species, unlike heteroantigens [from the Greek. heteros different, different], which are found in other mammalian species.

Founder of the science of blood groups, Karl Landsteiner in 1901. discovered differences in the blood of people who were subsequently designated as ABO blood groups. For a long time, information about group differences applied only to red blood cells. Later it became known that such differences are also inherent in other blood components: leukocytes, platelets, plasma proteins. To date, 26 erythrocyte antigen systems have been discovered (AB0, Rh-Rhesus, MNS, Kell, Lewis, etc.), including 270 antigens, leukocyte antigen systems (HLA, NA, NB, NC), platelet antigens (HPA) and 10 protein systems plasma. From the standpoint of modern immunohematology, each person has his own unique blood group - a set of antigens that can cause immunological incompatibility during transfusion of blood and its components, pregnancy, and organ transplantation.

However, in practical medicine, blood groups are traditionally understood as combinations of only erythrocyte antigens of the AB0 system, since they primarily determine compatibility during blood transfusion.

9.1. AB0 BLOOD TYPES

Blood group (in the traditional sense) is a combination of red blood cell antigens of the ABO system, which is genetically predetermined and does not change throughout life.

The AB0 blood group system includes two group antigens (agglutinogens) - A and B and two types of antibodies to them, which are currently designated anti-A and anti-B antibodies instead of the previously used α- and β-isohemagglutinins.

The uniqueness of the AB0 system is that in the plasma of non-immune people there are natural antibodies to an antigen that is not found on red blood cells. In all other systems of erythrocyte antigens, antibodies are not innate and can only appear as a result of antigenic stimulation (blood transfusion, pregnancy).

Various combinations Antigens and antibodies of the AB0 system form 4 blood groups, which, according to international nomenclature, are designated by letters based on the names of the available antigens: 0, A, B and AB.

Table 35

AB0 blood groups

More often people have the first (35%) and second blood groups (35-40%), less often - the third (15-20%) and fourth (5-10%) groups.

In most cases, antigen A has great antigenic strength, that is, it gives a pronounced agglutination reaction with anti-A antibodies. In 3-5% of people with the second group and in 25-30% of people with the fourth blood group, antigen A has weak antigenic properties. It is designated as antigen A2. Weak species antigen A gives weak agglutination (small, late) with anti-A antibodies, which can lead to errors in determining the blood group.

Anti-A antibodies, like antigen A, can be represented by two varieties that differ in the duration of action - anti-A 1 and anti-A 2. Anti-A 1 antibodies are classified as antibodies fast acting, and anti-A 2 is slow-acting. Therefore, when determining a blood group, the test must be carried out within 5 minutes.

In the serum of many newborns, group antibodies are absent. They usually appear during the first months of life, and their titer gradually increases, reaching a maximum at the age of 10-20 years. In old age and in immunodeficiency states, the antibody titer may decrease.

Clinical significance blood groups are very large, as it makes it possible to transfuse blood and its components from one person (donor) to another person (recipient) without complications.

Currently, only blood components are used for transfusion. Whole blood is transfused into exceptional cases- By vital signs and in the absence of necessary hemocomponents. Most often, red blood cells and plasma are used for transfusions, preferably of the same blood group as the recipient. If necessary, and in small quantities (up to 500 ml), it is possible to transfuse red blood cells not of the same type, but of blood compatible with the recipient.

When transfusion of blood and red blood cells, the following rules are strictly adhered to: the donor's red blood cells should not contain an antigen corresponding to the recipient's antibodies, since in this case agglutination and massive hemolysis of the injected donor red blood cells occurs - a life-threatening blood transfusion complication. A small amount of erythromass of blood group 0(I), the erythrocytes of which do not contain antigens A and B, can be transfused to a recipient with any blood group, therefore persons with blood group I are called “universal donors”. Up to 500 ml of red blood cells of A(II) and B(III) blood groups can be transfused, except for those of the same group, only to persons with AB(IV) blood group. Erythrocyte mass of AB(IV) blood group, even in small quantities, cannot be transfused into any group except IV, but a small amount of erythrocyte mass of all groups can be transfused into it. Therefore, individuals with AB(IV) blood group are called “universal recipients.”

When transfusing blood plasma, the donor's antibodies are taken into account. The donor's plasma should not contain antibodies directed against the recipient's antigens. Plasma of the 0(I) blood group contains both agglutinins - α and β and cannot be transfused into any blood group other than I. A small amount of plasma of the II and III blood groups can be transfused only into the 0(I) and the same groups. Group AB(IV) plasma does not contain agglutinins and can be transfused (in small quantities) to people with any blood group.

9.1.2. Methods for determining blood group

Determination of blood groups is carried out in accordance with the order of the Ministry of Health of the Russian Federation No. 2 dated January 9, 1998 “On approval of instructions for immunoserology.”

Currently, 2 groups of methods are used to determine blood group.

1. Methods based on the agglutination reaction:

Direct reaction with polyclonal reagents (standard isohemagglutinating sera of groups I-III) or with monoclonal reagents (anti-A and anti-B cyclones);

Cross method.

2. Methods of gel technology (combination of agglutination reaction and gel-

filtering).

Determination of ABO blood group using standard isohemagglutinating sera

Principle. Erythrocyte agglutinogens are detected using an agglutination reaction with standard sera containing agglutinins. Based on the presence or absence of agglutinogens in the red blood cells being studied, the blood group is judged.

Reagents.

1. Standard isohemagglutinating sera of groups 0(I), A(II) and B(III) of two different series of each group.

2. Standard isohemagglutinating serum AB(IV) group.

3. Isotonic sodium chloride solution - 0.9% NaCl solution.

Special equipment:

Preparatory work. Determination of blood groups should be carried out in good lighting and at a temperature of 15-25ºС. Vials with standard sera are placed in a special rack in the following order: on the left - standard sera of group 0 (I) (one behind the other), in the middle - standard sera of group A (II), and on the right - standard sera of group B (III). Separately, standard serum AB(IV) blood group is used as an additional control. A dry, clean eye dropper is placed into each bottle of standard serum. To rinse the glass rods, pour water into a beaker. An eye dropper is placed into a glass of isotonic solution.

Technique for determining blood group using standard sera. On the top of the plate they write the surname and initials of the person whose blood type is being determined. Divide the plate into 6 parts with a glass graph: 3 in 2 rows. Anti-A+B is written in the top left column; in the middle column – anti-B; in the right column - anti-A. Under the appropriate designations, one large drop (0.1 ml) of isohemagglutinating serum from groups 1-3 of two different series is applied to the plate using an eye pipette - 6 drops in total. Each pipette is immediately lowered into the same serum bottle from which it was taken. Blood for research is taken from a finger. Place one drop of blood in the well of a glass slide or on the bottom of the plate. Apply small drops of blood next to each drop of standard serum using a clean, dry glass rod. In this case, the blood drops should be approximately 10 times smaller than the serum drops. Mix drops of standard serum with nearby drops of blood using a glass rod. After stirring each drop, the glass rod is washed in a glass of water and wiped dry with cotton wool or filter paper. They notice the time. Rock the plate periodically for 3 minutes. After 3 minutes, add 1 drop of isotonic NaCl solution to those drops where agglutination has occurred and periodically shake the plate for another 2 minutes. 5 minutes after mixing the drops, the results of the reaction are assessed.

Interpretation of reaction results. The agglutination reaction in each drop can be positive or negative. With a positive reaction, that is, in the presence of agglutination, red grains of glued red blood cells, visible to the eye, appear in the mixture. The serum becomes completely or partially discolored. At negative reaction, that is, the absence of agglutination, the liquid remains uniformly colored red. The results of reactions in drops with serum of the same group should be the same. If agglutination occurs in all drops, that is, the blood being tested belongs to the AB(IV) group, then to exclude nonspecific agglutination, a control study is additionally carried out with standard serum of the AB(IV) group. To do this, apply 1 large drop of standard AB(IV) group serum to the plate and next to it - a small drop of the blood being tested. The serum and blood are mixed and the progress of the reaction is observed for 5 minutes, periodically shaking the plate. The absence of agglutination in this drop confirms the AB(IV) group of the blood being tested. The appearance of agglutination with AB(IV) group serum indicates the nonspecific nature of the observed agglutination.

Table 36

Evaluation of the results of blood group determination using standard isohemagglutinating sera

(-) lack of agglutination

(+) presence of agglutination.

Determination of the AB0 blood group using anti-A and anti-B cyclones

Principle. The same as when determining blood groups with standard sera - that is, identifying agglutinogens in the red blood cells under study using agglutinins contained in anti-A and anti-B coliclones.

Reagents: tsoliclone anti-A (pink) and tsoliclone anti-B (blue).

Coliclones anti-A and anti-B contain monoclonal antibodies anti-A and anti-B (class M immunoglobulins) and do not contain antibodies of other specificity. Coliclones are diluted ascites fluid from mice carrying anti-A and anti-B hybridomas.

Determination technique. Determination of blood groups should be carried out in good lighting and at a temperature of 15-25ºС. The determination can be made in native blood with a preservative or in blood without a preservative, including that taken from a finger prick. Mark the plate into 2 parts. Left side the plates are signed “anti-A”, the right one – “anti-B”. Apply one large (0.1 ml) drop of anti-A and anti-B zoliclones under the appropriate designations. Apply one small drop of blood (10 times smaller than the reagent drops) next to each drop of zoliclon. Mix drops of blood with the reagent with a glass rod, rinsing the rod in water after mixing and wiping it dry. They notice the time. Periodically shaking the record, wait 3 minutes. Agglutination of erythrocytes with coliclones usually occurs in the first 3-6 seconds, but the results of the reaction are assessed after 3 minutes so as not to miss late agglutination with weak varieties of antigen A or B.

Interpretation of the results. The result of the reaction can be positive or negative. A positive result is expressed in agglutination of red blood cells, visible to the naked eye in the form of small red aggregates that quickly merge into large flakes. In a negative reaction, the drop remains uniformly colored red, and no agglutinates are detected.

Table 37

Evaluation of the results of determining the AB0 blood group

using anti-A and anti-B zoliclones

(-) – absence of agglutination

(+) – presence of agglutination.

Determination of blood group of the ABO system using the cross method

Principle. Simultaneous determination of test blood erythrocyte agglutinogens using standard sera and test serum agglutinins using standard erythrocytes.

Reagents.

1. Standard isohemagglutinating sera of 0(I)αβ, A(II)β and B(III)α groups of two different series of each group.

2. Standard red blood cells of groups 0(I), A(II) and B(III).

3. Isotonic sodium chloride solution - 0.9% NaCl.

Special equipment: white plate with a wetted surface, eye pipettes, beakers, glass rod, cotton wool, alcohol, scarifiers.

Preparatory work. Determination of blood groups should be carried out in good lighting and at a temperature of 15-25ºС. Vials with standard sera are placed in a special rack in the following order: on the left - standard sera of group 0 (I) (one behind the other), in the middle - standard sera of group A (II), and on the right - standard sera of group B (III). A dry, clean eye dropper is placed into each bottle of standard serum. Test tubes or bottles with standard red blood cells are placed in the stand in the following order: group 0 (I) on the left, group A (II) in the middle and group B (III) on the right. To rinse the glass rods, pour water into a beaker. An eye pipette is placed into a glass containing an isotonic NaCl solution.

Determination technique. Blood for testing is taken from a vein or finger into a dry test tube. The blood is centrifuged or left to stand for 20-30 minutes to separate the serum. For better separation of the serum, after 3-5 minutes, separate the package from the walls of the test tube by circling it with a glass rod. Markings are made on the plate using a glass grapher in accordance with the table. In the upper part of the plate, near the corresponding designations, one large drop (0.1 ml) of standard isohemagglutinating sera of groups I-III of two different series is applied. At the bottom of the plate, one small drop (0.01 ml) of standard erythrocytes of blood groups I-III is applied at the corresponding designations. From the test tube with the blood being tested, carefully, so as not to shake the red blood cells, the serum is sucked out with a pipette and one large drop (0.1 ml) is applied to drops of standard red blood cells. Red blood cells are collected from the bottom of the test tube with the same pipette and applied one small drop (0.01 ml) next to each of the 6 drops of standard serum. Mix the serum with red blood cells in all 9 drops with a glass rod. After mixing each drop, the stick is washed in water and wiped dry. They notice the time. Rock the plate periodically for 3 minutes. After 3 minutes, add 1 drop of isotonic NaCl solution to those drops where agglutination has occurred and periodically shake the plate for another 2 minutes. 5 minutes after mixing the drops, the results of the reaction are assessed.

Table 38

Evaluation of the results of determining blood groups using the cross method

Interpretation of the results. The agglutination reaction in each drop can be positive or negative. With a positive reaction, that is, in the presence of agglutination, red grains of glued red blood cells, visible to the eye, appear in the mixture. The serum becomes completely or partially discolored. If the reaction is negative, that is, there is no agglutination, the liquid remains uniformly colored red.

The results of reactions obtained using standard sera and standard erythrocytes must match, that is, indicate the content of agglutinogens and agglutinins corresponding to the same blood group.

9.2. RH BLOOD Affiliation

The Rhesus erythrocyte antigen system, second in activity after the AB0 system, was discovered in 1940 by K. Landsteiner and Wiener. The antigen received its name from the Macacus Rhesus monkey in which it was discovered. The Rh factor is found on red blood cells, leukocytes, platelets, in various organs and tissues, as well as in human tissue fluid and amniotic fluid. The formation of the Rh antigen begins from 8-10 weeks of embryonic development.

Currently, the Rhesus system has more than 75 antigens, five of which are clinically significant: D, C, E, e. The absence of antigen D is indicated by the letter d. The most powerful antigen of the Rhesus system is the D antigen, which is what is meant by the term “Rh factor”. It is by the presence or absence of antigen D on red blood cells that blood is divided into Rh-positive (Rh+) and Rh-negative (Rh-). Various combinations of Rh antigens in the blood individuals There are 28 groups (phenotypes), which represent a set of Rh antigens - one from each parent (for example, CcDee, CCddEe). Fourteen phenotypes contain the D antigen and are Rh positive, while the other 14 do not contain the D antigen and are classified as Rh negative. However, such an assessment of Rh blood is used only for recipients. Donors are considered rh(-) if their red blood cells do not contain either antigen D, antigen C, or antigen E, that is, with the ccddee phenotype. This is because although C and E antigens are less active than D, antibodies can also be produced to them.

The number of Rh positive and Rh negative people varies among different races. Among Caucasians, including in the Russian Federation, the proportion of rh(-) individuals averages 14-16%, while among Mongoloids, the rh(-) phenotype occurs in less than 1% of the population, and their Rh conflicts are extremely rare.

In 1-3% of Rh-positive individuals, their red blood cells contain a weak variant of the D antigen (D u), which gives a small, questionable agglutination with anti-D antibodies. In these cases, the Rh status of the blood of recipients and pregnant women is assessed as rh(-), and the blood of donors is assessed as Rh (+).

The Rhesus system, unlike the AB0 system, does not have natural antibodies. Anti-Rhesus antibodies appear only after immunization of an Rh-negative organism as a result of a transfusion of Rh-positive blood or pregnancy with an Rh-positive fetus. Antibodies to Rh antigens persist for several years, sometimes throughout life. In most cases, the antibody titer gradually decreases over time, but when the Rh antigen enters the body again, it increases sharply (avalanche-like).

Rh antibodies differ in specificity (anti-D, anti-C, anti-E, etc.) and serological properties (complete and incomplete). Full antibodies cause agglutination of red blood cells in a saline environment when room temperature, and incomplete – at elevated temperature and in a colloidal medium (with the addition of gelatin, polyglucin, whey protein). Complete antibodies (IgM) are synthesized at the beginning of the immune reaction and soon disappear from the blood. Incomplete antibodies (IgG) appear later and are the cause of the development hemolytic disease newborns, as they pass through the placenta and cause hemolysis of fetal red blood cells.

Determination of Rh status blood test is based on the agglutination reaction of red blood cells of the blood being tested with antibodies contained in anti-Rhesus reagents. Anti-Rhesus reagents are divided into 2 groups: with complete and incomplete antibodies. Reagents containing complete IgM antibodies give an agglutination reaction in a saline environment. These include coliclones anti-D super, anti-C super, anti-E super, standard anti-Rhesus anti-D sera with complete antibodies, etc. Reagents containing incomplete antibodies of the IgG class (coliclone anti-D, standard universal reagents anti-Rhesus anti- D, anti-DC, anti-DCE, etc.), give an agglutination reaction only in a colloidal medium. Depending on the form of antibodies contained in the reagent, the determination of Rh blood is carried out in different conditions(in a saline or colloidal environment, at room temperature or when heated), therefore each reagent is accompanied by instructions for its use. Currently, preference is given to monoclonal anti-Rhesus reagents (coliclones). Gel technology is also used to determine Rh system antigens.

Determination of Rh blood status using anti-D super coliclone (anti-D IgM monoclonal reagent)

Principle. A antigen D of the studied erythrocytes is detected by an agglutination reaction in a saline medium with anti-D monoclonal antibodies contained in anti-D super coliclone.

Tsoliklone anti-D super is made on the basis of the culture liquid of a cell heterohybridoma obtained by merging a human lymphoblastoid line and a mouse myeloma cell line. The reagent contains monoclonal full antibodies anti-D of the IgM class and does not contain antibodies of other specificity, therefore it can be used to detect the D antigen in red blood cells of any blood group.

Reagents: zoliclone anti-D super; standard Rh(+) and rh(-) erythrocytes – to control the specificity of the reaction.

Research technique. Determination of the D antigen using anti-D super coliclone can be performed in preserved blood, in blood taken without a preservative, as well as in blood from a finger prick.

A large drop (about 0.1 ml) of anti-D super zolicone is applied to a plate with a wetted surface, and next to it is a small drop (0.01-0.05 ml) of blood and the blood is mixed with the reagent with a glass rod. Wait 20-30 seconds, and then periodically shake the record. After 3 minutes, evaluate the results of the reaction.

Interpretation of the results. In the presence of agglutination, the blood is assessed as Rh-positive, and in the absence of agglutination - as Rh-negative. To control specificity, each study requires a reaction with standard D-positive and D-negative erythrocytes. The results of determining the Rh identity of the blood being tested are taken into account as true only if the reagent gave an agglutination reaction with standard Rh-positive erythrocytes, but there was no agglutination with standard Rh-negative erythrocytes.

Blood samples that, when tested with anti-D zolicone, gave super results negative result, must be further tested using reagents containing incomplete IgG antibodies to detect the D u antigen (polyclonal serum or monoclonal anti-D reagent).

9.3. CHECK QUESTIONS FOR THE CHAPTER “GROUPS AND RH BLOOD BLOOD”

1. What does the concept of “blood group” mean in practical medicine and from the standpoint of modern immunohematology?

2. Describe the blood groups of the AB0 system.

3. By what methods can you determine your blood type?

4. What principle underlies all methods for determining blood group?

5. What reagents are used to determine blood group by direct reaction?

6. Describe the results of determining the second blood group using a direct reaction.

7. Why is the cross-sectional method of determining blood group so called?

8. Reagents for cross method determination of blood group.

9. Results of determining the third blood group using the cross method.

10. What are zoliclones?

11. Results of determining the fourth blood group with zoliclones.

12. What rules must be followed when transfusing red blood cells and blood plasma?

13. What antigens belong to the Rhesus system?

14. What is the difference between the AB0 and Rhesus antigen systems?

15. Clinical significance of Rh system antigens.

16. By what principle is the blood of donors and recipients classified as Rh positive or Rh negative?

17. What reagents can be used to determine the Rh status of blood?

18. What is the difference between anti-D and anti-D super zoliclones?

19. What is D u antigen? Its clinical significance.

20. Phenotype of a Rh-negative donor.

Chapter 10

QUALITY CONTROL OF LABORATORY RESEARCH

Quality control laboratory research in KDL is carried out in accordance with the order of the Ministry of Health of the Russian Federation No. 45 dated February 7, 2000 “On the system of measures to improve the quality of clinical laboratory tests in healthcare institutions of the Russian Federation.” The quality of laboratory tests must meet the requirements for analytical accuracy established by the Ministry of Health of the Russian Federation and serving as industry standards.

A number of concepts are used to assess the quality of research.

Accuracy of measurements - quality of measurements, reflecting the closeness of their results to the true value of the measured value.

Measurement error – deviation of the measurement result from the true value of the measured value.

Systematic measurement error – part of the measurement error that remains constant or changes naturally with repeated measurements of the same measured quantity.

Random measurement error - part of the measurement error that changes randomly with repeated measurements of the same measured quantity.

Correct measurements - quality of measurements, reflecting closeness to zero systematic errors.

Analytical series - set of measurements laboratory indicator, performed simultaneously under the same conditions without reconfiguring and calibrating the analytical system.

Intra-batch reproducibility (convergence) of measurements - the quality of measurements, reflecting the closeness to each other of the results of measurements of the same material, performed in the same analytical series.

Inter-run reproducibility is the quality of measurements, reflecting the closeness to each other of the results of measurements of the same material carried out in different analytical series.

Overall reproducibility – quality of measurements, reflecting the closeness to each other of all measurements of the same material (determined by intra- and inter-run reproducibility).

Set value – method-dependent value of the determined indicator, indicated by the manufacturer of the control material in the passport (instructions). Due to the fact that the true value of the measured value cannot be established absolutely accurately, in practice, instead of the term “true value”, the term “established value” is used.

Ensuring the quality of laboratory research in KDL is carried out by a system of in-laboratory quality control, in which the reproducibility and accuracy of research is systematically determined.

The systematic measurement error characterizes right measurements, which is determined by the degree of coincidence of the average result of repeated measurements of the control material () and the established value of the measured value. The difference between them is called the magnitude of the systematic error or displacement, shift and can be expressed in absolute and relative values. Systematic error, expressed in relative values, or relative systematic error, is calculated as a percentage using formula 1:

B = (1), where

– average value of measurements of the controlled material;

Set value.

Random error reflects the scatter of measurements and is manifested in the difference between the results of repeated measurements of the determined indicator in the same sample. The mathematical value of the random error is expressed by the standard deviation (S) and the coefficient of variation (CV).

Standard deviation(S) is calculated using formula 2:

where is the arithmetic mean of the measurement results, calculated using formula 3:

The coefficient of variation(CV) is calculated as follows.

Duration of bleeding according to Duque - what does this type of analysis mean? This question may be of interest to many people who were prescribed such a “strange” examination. Why it is carried out and how to understand the results. This will be discussed in this article.

What kind of analysis is this?

The duration of bleeding according to Duque (developed by William Duke or Duke) is used extremely rarely today. The main goal this study is to determine the rate of blood clotting. This process is very important for our body. It allows you to avoid serious blood loss if you receive an injury or cut.

How is this analysis carried out?

The algorithm for performing a Duke study is quite simple and is as follows:

1. A thin needle is prepared for the study.
2. Next, a small puncture of the skin layer is made. Its depth must be at least 3 millimeters. The Duke puncture can be done in any part of the body. Most often it is either a finger or an earlobe.
3. For the next step you need filter paper. It is applied to the puncture site every thirty seconds. This is done until there are no traces of blood left on it.

The bleeding time according to Duque, that is, the norm, should be three minutes. But here everything is individual. Each person's blood clots at a different rate. Therefore, for one patient the norm may be two minutes, for another four. But on average this figure should be three minutes.

If the duration of bleeding is longer, then a more thorough investigation should be performed. When the norm is exceeded, there is a high risk of major blood loss. This is especially important if surgery or childbirth is coming.

When is the test ordered?

It is necessary to determine whether the norm for coagulation is exceeded or not quite often.

As a rule, such a study can be prescribed in the following cases:

• if there is a suspicion of problems with platelets or a clotting reaction;
• if the patient is undergoing surgery;
• before childbirth;
• if there is a suspicion of hemorrhagic disorders.

It is worth noting that such analysis is not carried out often. As a rule, it is used in small hospitals where there is no equipped laboratory. An analysis was carried out and the norm was determined using this method and it can be anywhere. This study can be done even at home. Therefore, it is practiced in cases where there are no other ways to determine blood clotting time.

How to prepare for the analysis?

Any research must be carried out only under certain conditions. To ensure the accuracy of the analysis results, it is necessary to follow some rules before starting it.

Here, as in the case of other blood tests, the following should be adhered to:

1. Several hours, at least eight, before visiting the treatment room, you should refrain from eating. Therefore, the study is carried out in the morning. In this case, you are allowed to drink plain water.
2. Two days before the test, you need to stop drinking alcoholic beverages. It is also advisable not to smoke at least four hours before the start of the study.
3. It is also undesirable to overstrain the body with physical and emotional stress.
4. Before entering treatment room need to calm down. To do this, you should sit down and sit quietly for about fifteen minutes.

All this will help you get more accurate results analysis. In addition, if the patient is taking medications that may affect the blood clotting process, the doctor must be informed about this. In this case, he can make adjustments to the transcript of the analysis.

Why is the norm broken?

Why do blood clotting abnormalities occur? What is the solid basis for this? It is worth noting some innate factors here.

In some cases, longer reaction times may be passed from parents to children. But such diseases are quite rare.

As a rule, deviation from the norm occurs for the following reasons:

• lack of certain vitamins, or rather C;
• excessive consumption of alcoholic beverages. This bad habit adversely affects all organs and processes occurring in the body;
• liver problems or failure;
• leukemia;
• some other diseases, such as amyloidosis or uremia.

In some cases, the cause of bleeding that lasts too long may also be due to the use of a number of medications. For example, this group includes Aspirin, a number of antibiotics and other drugs. If this is the reason, then the problem is easily solved. It is enough to stop taking these medications. If the reason is different, then treatment cannot be avoided.

Blood clotting is caused by a protein called fibrin. Its activity is the formation of blood clots and blood thickening. Coagulation is very important for normal operation the entire body, since it is precisely this that allows you to avoid the loss of fluid and formed elements in case of various types of damage. If a blood test for clotting and bleeding duration shows any abnormalities, then doctors need to establish the cause of this situation as quickly as possible, since the consequences can be different, even death. This determines the need to monitor the blood coagulation function, as well as monitoring the blood vessels. The normal duration of bleeding is considered to be 2-3 minutes after collecting biological fluid for analysis.

Why know clotting time?

Clotting time describes several functions of the hemostatic system - how quickly blood clots form, the ability of platelets to stick to each other, and also gives information to the doctor about how long it will take for the body to close the leak if the integrity of the vascular walls is violated. During this time, fibrinogen turns into fibrin, forming a “plug”, which prevents large losses of biological fluid.

A study of the duration of bleeding and analysis of a detailed coagulogram is performed when:

• prenatal period, as complications are possible.
• before performing medium and large surgical interventions.
• chronic blood loss due to pathologies such as hemorrhoids, Malory-Weiss syndrome, erosions of the digestive organs, precancerous and cancerous conditions.
• thrombotic disorders, including varicose veins.
• autoimmune conditions.

Reduced blood clotting causes the risk of prolonged blood loss during surgical operations or due to injury. A loss large quantity formed elements and plasma threatens the body and its vital functions. A special risk group is formed by women in the postpartum period, during menstruation.

Another such group are men with a disease such as hemophilia, which implies the absence of certain proteins that cause hemostasis. Moreover, representatives of the fairer sex are only carriers of the genes of this pathology. Decreased coagulation also occurs against the background of diabetes mellitus or regular use of antiplatelet agents and anticoagulants.

It is important to understand that hypercoagulation is also not considered a normal option, since there is a high probability of developing so-called vascular accidents - thrombosis of any location, including heart attacks and ischemic strokes. This is due to the formation of clots inside the vascular bed, which clog the blood flow through the vessels, causing necrosis of the tissue that feeds this line.

Other results of hypercoagulability are varicose veins, development of hemorrhoids and other diseases. The formation of increased coagulability is caused by dehydration, pathologies of the kidneys, liver, and in women it is sometimes observed while taking oral hormonal contraceptives.

Bleeding duration is normal

The blood clotting rate in women and men of the same age is usually the same. The only exception is during pregnancy. But in children and elderly people it differs somewhat due to hormonal changes. Carrying a baby is different in that coagulation becomes more active, since the hemostatic system here is responsible for two organisms at once and must respond more actively to problems that arise.

In children of the first year of life, blood clotting is also different, and in newborns, PTT increases by 2-3 seconds. In premature babies, the prothrombin time is also not a few seconds higher.

The following indicators are considered the main components of a coagulogram.

1. The platelet count, which should not fall below 150 g/l. In an adult upper limit the norm is 380 g/l, in children – 320-350.
2. Sukharev's clotting time involves taking blood from a finger. The beginning of this process occurs after 30-150 seconds, the maximum permissible duration is 6 minutes, but doctors consider 5 minutes, that is, 300 seconds, to be the norm.
3. Lee-White analysis involves studying this indicator in venous blood. How long it will stop depends on the individual characteristics of the body, but 5-10 minutes is considered normal.
4. Also, sampling from a finger is carried out when determining time according to Duque; pathology is a time of 4 minutes.
5. Collection of biological test material from a vein is necessary to study thrombin time, acceptable limits are 15-20 seconds.
6. The prothrombin index can be determined from both capillary and venous blood. In the first case target values are 90-105%, and in the second – 93-107%.
7. APTT – activated partial thromboplastin time. Acceptable numbers are 30-50 seconds.
8. Fibrinogen is a protein from which fibrin is formed. In children in the first days of life, its amount is 1.5-3 g/l, and in adults – 2-4 g/l.

Coagulation time according to Sukharev

Blood sampling is carried out from a finger, it is best to do it on an empty stomach or several hours after eating. Any special recommendations There is no guidance on preparing a patient for this test. The only important thing is that it is capillary blood. Sukharev coagulation time does not reflect platelet activity in the blood or in how many seconds deoxygenated blood will curl up.

The first drop obtained is removed with a swab, after which the laboratory assistant waits for the next one to appear, which must be placed in a special flask. It is rocked alternately in both directions. This process is timed with a stopwatch. As soon as biological fluid freezes, the clock is stopped, and the period from start to finish is the coagulation time. It usually takes from 30 to 120 seconds normally.

From the moment fibrin forms until the end of coagulation itself, no more than 5 minutes should pass. This technique allows us to determine the stage of fibrin formation from fibrinogen when it ceases to be soluble.

Morawitz method

This method for determining blood coagulation is used quite widely today, and it is very easy. Blood sampling according to Moravits is performed on an empty stomach; preparation requires avoiding the use of alcoholic beverages 2-3 days before the test. It is also not recommended to smoke or drink coffee on the day of the test. Doctors advise drinking only water, which increases the accuracy and efficiency of the study.

The laboratory assistant places a drop of blood, which was taken from a finger, on a glass slide. Then the stopwatch starts. Every 30 seconds a glass tube is placed into this drop. As soon as the fibrin thread is visible behind it, the measurement stops and the resulting time is the result of the Morawitz analysis. The norm is in the range of 3-5 minutes.

Duque clotting method

This technique, which studies hemostasis, also requires blood sampling on an empty stomach, preferably in the morning. The patient's earlobe is pierced using a special needle called a Frank needle. Every 15 seconds, paper is applied to the puncture site. Once there are no more traces of blood on it, testing is completed. Normal indicators imply stopping bleeding due to the formation of fibrin threads, clots and thrombi in 1-3 minutes.

Coagulability according to Lee-White

The method for assessing the indicators of the hemostasis system according to Lee-White implies the time during which venous blood clots in a test tube. There is no need to take capillary blood from the patient from a finger.

The purpose of this analysis is to determine as accurately as possible the first stage of coagulation, when prothrombinase is formed. This point plays a very important role and is important for doctors, since it depends on several factors, including:

• permeability of the vessel wall;
• amount of plasma proteins;
• the level of platelets and other formed elements that are capable of aggregation.

The ratio of the above components is considered a key element of hemostasis for healthy person. Lee-White clotting times may sometimes differ. This is due to the conditions and technique of performing the procedure. In a regular laboratory glass test tube it is 4-7 minutes, and due to the fact that other materials have different physical properties, the duration of the test in them increases to 15-25 minutes. An increase in clotting will indicate the presence excessive activity the first link of hemostasis.

The main reasons for deviations from the norm

Changes in blood clotting time indicators indicate the development of various pathological processes in organism. Most often, the reasons for the increased result of the analysis of the hemostasis system indicate such pathologies.

1. Liver diseases, especially the stages of decompensation of cirrhosis, hepatitis, oncological conditions, when the parenchyma of the organ is assessed as incompetent.
2. A deficiency of coagulation factors, or their inferiority, which leads to the fact that normal proteins are contained in a reduced amount and there are simply not enough of them to ensure normal coagulation.
3. Terminal stages of disseminated intravascular coagulation syndrome.

An increase in the indicator is also observed when the patient is taking anticoagulants and antiplatelet agents, or heparin therapy. This necessitates testing for them more often than for healthy people. For example, with regular use of warfarin, monthly INR monitoring is required.

A shortening of hemostasis indicators is observed in the following pathologies.

1. In the initial stages of disseminated intravascular coagulation syndrome, this stage is called hypercoagulation.
2. Diseases that are noted increased risk thrombosis - hypertension, atherosclerosis, dyslipidemia with increased cholesterol levels, various thromboses, thrombophilia, varicose veins.
3. Long-term use of oral hormonal contraceptives.
4. The presence of bad habits such as smoking and drinking alcohol.
5. Dehydration.
6. On the background long-term use corticosteroids, which can influence absolutely all processes occurring in the body.

It is important to understand that laboratory conditions are somewhat different from those inside a closed system of the body, since when determining the state of the hemostatic system, only one indicator is assessed at a time, while inside the homeostasis of the body, all factors influence coagulation at once. This necessitates the need to study several indicators at once to assess the overall picture.

We owe normal blood clotting to fibrin, which is part of its composition. Large blood losses are fraught with anemia, weakness, general malaise, fainting. People with poor coagulability are forced to monitor integrity skin and fear of injury.

An analysis for the duration of bleeding according to Duque is taken before surgery or if there is a tendency to bleeding. If clotting is poor, the problem is solved by using medications and folk remedies.

Studies regarding the characteristics of blood clotting are carried out before some important procedures and manipulations:

• if childbirth is coming;
• elective surgery;
• worries varicose veins veins;
• autoimmune diseases;
• chronic hemorrhoids;
• bleeding became regular.

Every month women experience menstruation, if clotting leaves much to be desired, they need to take hemostatic drugs. In men, against the background of this feature, hemophilia of the hereditary type develops. Hemophilia is a disease in which fibrin is absent completely or partially. People with hemophilia rarely live beyond 50 years of age. You have to be on your guard when you're sick diabetes mellitus, the duration of their bleeding may increase due to the use of anticoagulants.

A few words need to be said about too thick blood. This symptom is no less alarming. The viscous substance does not circulate well through the vessels, which can cause a stroke. Stagnation does not allow the brain and internal organs receive a sufficient amount of oxygen and other useful components.

When the blood clots instantly, unpleasant consequences become varicose veins, hemorrhoids. This is why doctors don't recommend
Women use contraceptives in the form of pills, they make the blood thicker.

Indicators of bleeding duration according to Duque

Duque's bleeding time is the easiest way to determine clotting. It is carried out as follows:

1. Armed with a special needle, the healthcare worker punctures the patient's skin. Frank's needle consists of a hollow body and a trigger and a spring. The latter allows the laboratory assistant to control the depth of the puncture.
2. For the Duque test, you need to make a minimally deep puncture.
3. The Bouquet test involves the use of capillary blood, so it is taken from a finger or earlobe.
4. Every 15 seconds, apply paper to the puncture site. The goal is to study when the paper becomes stain-free.
5. The minimum time allowed for blood clotting is 60 seconds, the maximum is 180 seconds.

The table below shows the main indicators that make it clear what kind of blood clotting the patient has.

How to get reliable analysis results

To avoid having to retake the test, blood is donated according to Duque taking into account the following requirements:

• collection of biomaterial is carried out on an empty stomach in the morning;
• You should not drink alcohol for 24 hours before taking the test;
• smoking is not allowed for 4 hours;
• avoid stress.

What does prolonged bleeding indicate?

Prolonged bleeding may indicate the following pathologies:

• Werlhoff syndrome;
• thrombopenic purpura;
• mourn;
• intoxication with phosphorus compounds;
• diathesis of hemorrhagic type;
• leukemia;
• cirrhosis of the liver of a splenomegalic nature;
• long-term use of antiplatelet agents, which include frequently used ascorbic acid and medicines where it is the main active ingredient;
• bleeding with concomitant hypofibrinogenemia;
• DIC disease;
• congenital abnormalities of blood vessels, characterized by deterioration of precapillary contraction.

Medicines to increase the number of fibrinogens in the blood

Low blood clotting is treated with medications that affect the amount of fibrinogen in the blood. The list of drugs looks like this:

1. Coagulants – Fibrinogen, Thrombin, Vicasol.
2. Synthetic based products – Aminocaproic acid.
3. Products of animal origin – Pantripin, Aprotinin.
4. Helping the formation of blood clots - calcium chloride, Serotonin adipate.
5. Reducing permeability properties vascular network– arnica, yarrow, nettle, rutin, Adroxon.

Traditional recipes for better blood clotting

If the analysis showed a long duration of bleeding according to Duque, traditional healers We recommend using the following proven recipes:

1. Brew tincture or decoction from yarrow, they will help quickly regenerate tissue and stop nosebleeds.
2. Brew pine nut shells in boiling water and use an extractor. This method helps stop blood discharge from the mouth.
3. If the patient is faced with a burn, an infusion of marshweed will help, normalizing blood circulation.

Blood consists of cells (elements - leukocytes, erythrocytes, platelets, etc.) and plasma. Blood circulates through the vessels of the whole body and penetrates all organs and tissues, delivering nutrients and oxygen to them, regulates water-salt metabolism, participates in the regulation of acid-base balance, maintains a constant body temperature, and performs a protective function (presence of antibodies).

Why do you need a blood test?

Analysis of blood parameters is most important, since in a healthy person these indicators are relatively constant, any change in them is an indicator of changes in the human body.

How to take a blood test correctly?

As a rule, blood from a vein is used for analysis. Blood sampling occurs in the morning and on an empty stomach. If necessary at another time, you must refrain from eating for 3 hours. Juice, tea, coffee (especially with sugar) are not acceptable. You can drink water.

What will a general clinical blood test show?

A general blood test contains information on the number of indicators such as red blood cells, platelets, leukocytes (and their types), hemoglobin content, and color indicator.

General blood test indicators.

Hemoglobin.

Many blood diseases (including hereditary ones) are closely related to a violation of the structure of hemoglobin. Hemoglobin is a red pigment in the blood that carries oxygen to tissues.

Hemoglobin norm:

• Hemoglobin norm for men: 130.0 - 160.0 g/l
• Hemoglobin norm for women: 120.0 - 140.0 g/l

What does a change in hemoglobin norm indicate?

A decrease in hemoglobin norm is observed in various anemias and blood loss. An increase in the norm is observed with a decrease/increase in the number of red blood cells, if the blood thickens.

Red blood cells.

Red blood cells are blood cells that are produced in bone marrow and contain hemoglobin.

Red blood cell norm:

• Red blood cell norm for men: 4.0 - 5.0*1012/l of blood
• The norm of red blood cells for women: 3.9 - 4.7 * 1012 / l of blood

What does a change in the red blood cell rate indicate?

A decrease in the number of red blood cells is observed with a decrease in bone marrow function, with changes in the bone marrow (leukemia, malignant tumors, etc.), with a lack of iron in the body, a lack of vitamin B12, and with bleeding.

Erythrocyte sedimentation rate (ESR).

This indicator is expressed in millimeters of plasma, which exfoliates within an hour.

ESR norm:

• ESR norm for men: 2-15 mm/h
• ESR norm for women: up to 10 mm/h

What does a change in the ESR standard indicate?

A change in erythrocyte sedimentation rate is not a sign for any specific disease. But, at the same time, the acceleration of ESR indicates that there is a pathological process.

Platelets.

Platelets are blood cells that contain a nucleus. Platelets are involved in blood clotting.

Normal platelet count.

There are 180-320*109 platelets in 1 liter of blood. A sharp decrease is observed, for example, with Werlhof's disease, with a symptomatic lack of blood clots.

Leukocytes.

White blood cells are colorless cells that absorb bacteria and dead cells and produce antibodies.

Leukocyte norm.

The average number of leukocytes ranges from 4*109 to 9*109 in 1 liter of blood. An increase in the number of white blood cells may indicate certain infections, blood diseases, inflammation, malignant formations, intoxication, allergies, oxygen starvation. A decrease in the number of leukocytes can be observed with radiation injury, contact with chemicals, upon reception medications, with viral bacterial infections, with a disease of the blood system.

Blood clotting indicators.

Clotting time- the moment from blood contact with a foreign surface to the formation of a clot. Blood clotting time (according to Sukharev) is normal: 2-5 minutes.
If the clotting time is longer: significant deficiency of plasma factors, hereditary coagulopathy, disorders of fibrinogen formation, liver disease, heparin treatment.
If the clotting time is shorter: hypercoagulation after bleeding, postoperative and postpartum periods, Stage I of DIC syndrome, side effects of contraceptives.

Bleeding time- its duration.
The Duke bleeding time norm does not exceed 4 minutes.
An increase in bleeding time is observed with severe thrombocytopenia and/or severe violations their functions (thrombocytopathies). It must be remembered that 60% of people with this pathology test negative, and the bleeding time is normal.

Blood chemistry.

For many diseases, it is the main thing for making a correct diagnosis. These are diseases such as: pancreatic diseases, acute diseases liver, kidney disease, heart disease, many hereditary diseases, vitamin deficiency, intoxication, etc.

Reduced protein - protein starvation, inhibition of protein synthesis processes, with chronic diseases, inflammation, malignant formations, intoxication, etc.

Increase in the amount of lipids and their fractions: in case of violation fat metabolism, in case of violation functional abilities liver and kidneys.

A sharp increase in concentration direct bilirubin - characteristic feature most liver diseases, with jaundice. With hemolytic jaundice, the concentration of indirect bilirubin in the blood increases.