One of the main tests of blood is to determine the time during which it coagulates. Such a study is called the Lee-White test. In addition, plasma recalcification, clot retraction time, APTT indicator and other equally important data are subject to determination. Retraction is a rather interesting process. Consider it in more detail below.
Coagulation time
The time during which blood coagulates, according to Lee-White, is defined as the time between the moment of its collection from a blood vessel and the moment of clot formation, i.e. its coagulation.
This indicator is nonspecific and characterizes the coagulation system in general. And what is blood clot retraction?
For this test, one milliliter of blood must be drawn into a test tube. In this case, both glass and silicone tubes can be used during the study. After this, the blood should be kept at a temperature of 37 degrees Celsius. If blood coagulation is normal, then in a normal test tube it will coagulate in 5-7 minutes, and in a silicone one - in 20-25 minutes.
An increase in clotting time may occur in some cases. These include:
• Anemia resulting from large blood loss.
• Pathological condition of platelets.
• Excess blood anticoagulants (drugs that have a thinning effect on the blood).
• Lack of coagulation factors. Decryption of blood in this case will be inaccurate.
If blood coagulation does not occur at all, then in most cases this indicates a sharp deficiency of fibrinogen.
The reverse situation, in which a reduced coagulation time is observed , is very rare.
Contact Activation Index
Sometimes, during the test, specialists determine an indicator such as contact activation index. This indicator reflects the ratio that arises between the coagulation time in a conventional tube and the coagulation time in silicone. The normal level of this indicator is 1.7-3.0.
With violations of the liver, some links of hemostasis and with an excess of anticoagulants in the blood, an increased contact activation index can be observed.
What is retraction? This is of interest to many.
Plasma Recalcification Time
Plasma recalcification time is the time period required to form a blood clot after calcium salts have been added to the plasma. A range of a couple of minutes is considered normal.
In addition, it may be necessary to determine the activated recalcification time (kaolin time or ABP indicator). This parameter differs from the previous one only in the technique with which the test is carried out. The standard ABP is an interval of 50-70 seconds.
Reasons for lengthening recalcification time
In some cases, an extended recalcification time may be observed. This is possible if:
• There is a lack of certain coagulation factors.
• Blood contains an excessive amount of anticoagulants.
• There is a platelet pathology.
In that case, if the test shows a reduced recalcification time, then we can talk about increasing the activity of the coagulation system. What else can the transcript of blood show?
Definition of APTT
This indicator is also called APTT (kaolin-mullet time) and is an activated partial thromboplastin time. This test can be used to determine the function that plasma coagulation factors perform.
The normal range of ASTV is between 35 and 45 seconds.
In some cases, an increase in APTT may be observed. This indicates:
• Excessive blood levels of anticoagulants.
• The presence of idiopathic thrombocytopenic purpura.
• Some liver pathologies.
• ICE syndrome.
• The development of hemophilia.
In the event that the APTT is below 35 seconds, this may indicate an incorrect technique for taking a blood sample for the test or increased clotting.
Blood clot retraction
PKC is a biological process in which a decrease or complete separation of a blood clot or platelet plasma from blood serum occurs.
Due to platelet retraction, the serum is isolated from the solid residue. When determining retraction, the volume of serum isolated from a blood clot is subject to measurement. Retraction is an indicator that is mainly used to quantify the density of a clot that forms as a result of blood coagulation. The essence of this method is that the blood is left for some time, allowing it to clot. After that, the relationship between the liquid part of the blood after the formation of a clot and the initial volume of blood that was taken for analysis is evaluated.
If the retraction of a blood clot is determined by the standard method, then the rate of 45-65% is normal.
Deviations from the norm
In some pathological conditions, a reduced retraction rate may be observed. This is possible with:
• Reduced platelet count.
• Increased red blood cell count.
• Some types of hereditary diseases.
• Hemorrhagic Aleikia Frank.
• Werlhof's disease.
If there is an increased rate of retraction of a blood clot, then this indicates the presence of anemia or an increased amount of fibrinogen contained in the blood. Retraction can be completely absent in diseases such as Bright's disease, Banti's disease, pneumonia, leukemia, and diabetes. Retraction in medicine is an important indicator of blood quality and, accordingly, health status.
Thromboelastography and coagulography
When determining the activity of a coagulation system, some laboratories prefer not to use standard coagulogram tests, but special instruments called:
- Coagulograph.
- Thromboelastograph.
These devices make it possible to obtain a graphic image of the blood coagulation process. If the laboratory complies with the necessary recording technique, then as a result of image analysis, hemostasis can be estimated with high accuracy. Thromboelastography allows you to determine how long the three main 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. Blood clot retraction is also often measured.
Autocoagulogram
An autocoagulation test or an autocoagulogram is a fairly rare technique for studying a coagulation system.
When conducting such a study, blood requires preliminary special preparation. Then a specific reagent is added to it at regular intervals for an hour. With each addition, blood coagulation is determined. After that, according to the data obtained as a result of the test, a graph is built. This graph reflects the existing relationship, as well as the balance that occurs between the coagulation system of the blood and the anticoagulation.
If a shortened autocoagulogram technique is used, then all testing takes no more than ten minutes.
The method of constructing and subsequent analysis of an autocoagulogram is most often used if the patient is on long-term therapy using heparin agents or for the diagnosis of hemophilia.
We considered such a thing as retraction. This is an important indicator of coagulation.