Retraction is ... Definition. Retraction of the blood clot
One of the main tests of blood isDetermination of the time during which it coagulates. Such a study is called the Lee-White test. In addition, the definition is subject to plasma recalcification, clot retraction time, APTT index and other equally important data. Retraction is a very interesting process. Let us consider it in more detail below.
The time during which the coagulation takes place
The time during which the blood is folded, according to Lee-White, is defined as the time between the time of its collection from the blood vessel and the moment of clot formation, that is, its clotting.
This indicator is non-specific and gives a characteristic of the coagulation system in general. And what is the retraction of the blood clot?
For this test, you need to dial intest tube one milliliter of blood. In this case, both glass and silicone test tubes can be used during the study. After that, the blood should be kept at a temperature of 37 degrees Celsius. If blood clotting is normal, then in a conventional test tube it will curd over 5-7 minutes, and in silicone - in 20-25 minutes.
Increasing the clotting time can occur in some cases. They include:
• Anemia, which resulted from a large blood loss.
• Pathological state of platelets.
• Excess in the blood of anticoagulants (agents that have a diluting effect on the blood).
• Lack of coagulation factors. The interpretation of the blood in this case will be inaccurate.
If blood clotting does not occur at all, in most cases this indicates a severe shortage of fibrinogen.
The reverse situation, in which reduced coagulation time is observed, is very rare.
Contact Activation Index
Sometimes, during the test, specialistsdetermine such an indicator as the index of contact activation. This indicator reflects the relationship that arises between the time of blood coagulation in a conventional tube and the time of clotting in a silicone one. The normal level of this indicator is 1.7-3.0.
In cases of liver disorders, some parts of the hemostasis and an overabundance in the blood of anticoagulants, an increased index of contact activation may be observed.
What is retraction? This is of interest to many.
The time of recalcification of blood plasma
The time of plasma recalcification isthe time interval that is required to form a blood clot after calcium salts have been added to the plasma. The range of a couple of minutes is considered normal.
In addition, there may be a need fordetermination of the activated recalcification time (kaolin time or ATS index). This parameter differs from the previous one only by the method used to perform the test. The norm of the AVR is the interval of 50-70 seconds.
Reasons for lengthening the recalcification time
In some cases, an extended recalcification time can be observed. This is possible if:
• There is a lack of certain factors of blood clotting.
• The blood contains an excessive amount of anticoagulants.
• There is a pathology of platelets.
If the test shows a reduced recalcification time, then we can speak of an increase in the activity of the coagulation system. What else can show the transcript of the blood?
Definition of APTT
This indicator is also called APTV(kaolin-cephalic time) and is an activated partial thromboplastin time. This test can be used to determine the function performed by plasma clotting factors.
The normal range of ACH is in the range of 35 to 45 seconds.
In some cases, an increase in APTT can be observed. This indicates:
• Excessive blood levels of anticoagulants.
• Presence of idiopathic thrombocytopenic purpura.
• Some liver pathologies.
• The ICE Syndrome.
• Development of hemophilia.
In the event that the APTT is below 35 seconds, this may indicate an incorrect technique for sampling a blood sample for the test or for increased coagulability.
Retraction of the blood clot
PKC is a biological process in which there is a reduction or complete separation of the blood clot or platelet plasma from the blood serum.
Reduction is due to cutback of platelets, inresulting in the isolation of the serum from the dense residue. When determining retraction, the volume of serum isolated from the blood clot is measured. Retraction is an indicator that is mainly used to quantify the density of a clot that is formed as a result of blood clotting. The essence of this method is that the blood is left for a while, allowing it to curdle. After this, the relationship between the liquid part of the blood after clot formation and the initial volume of blood that was taken for analysis is evaluated.
If the retraction of the blood clot is determined by the standard method, then the indicator in 45-65% is normal.
Deviations from the norm
In some pathological conditions, a reduced retractive index may be observed. This is possible with:
• Decreased platelet count.
• Increased number of red blood cells.
• Some types of hereditary diseases.
• Frank's hemorrhagic aleukia.
• Illnesses of Verlhof.
If there is an increased rate of retractiona clot of blood, this indicates anemia or an increased amount of fibrinogen found in the blood. Completely no retraction can occur with such diseases as Bright's disease, Banty's disease, pneumonia, leukemia, diabetes. Retraction in medicine is an important indicator of the quality of blood and, accordingly, the state of health.
Thromboelastography and coagulation
Some laboratories, when determining the activity of a coagulation system, prefer not to use standard coagulogram tests, but special devices, which are called:
These devices enablea graphic representation of the process of blood clotting. If the laboratory complies with the necessary recording technique, then as a result of image analysis it is possible to evaluate hemostasis with high accuracy. Thromboelastography allows you to determine how long the three major phases of blood coagulation last. In addition, it is possible to evaluate some specific indicators. Coagulography is a highly specific method by which it is possible to determine the duration of various processes. Thrombus retraction is also often measured.
An autocoagulation test or an autocoagulogram is a very rarely used technique for studying a coagulation system.
When carrying out such an investigation, the blood requirespreliminary special training. After that, a specific reagent is added thereto at regular intervals for an hour. With each addition, blood coagulability is determined. After this, according to the data obtained as a result of the test, a graph is constructed. This graph reflects the existing relationship, as well as the equilibrium that arises between the coagulating system of blood and anticoagulant.
If the abbreviated technique of carrying out an autocoagulogram is used, then all testing takes no more than ten minutes.
The method of constructing and subsequent analysis of an auto-coagulogram is most often used if the patient is on long-term therapy using heparin drugs or for the purpose of diagnosing hemophilia.
We have considered such a concept as retraction. This is an important indicator of coagulation.