One of the main blood tests is to determine the time during which it clots. Such a study is called a Lee-White test. In addition, plasma recalcification, clot retraction time, APTT index and other equally important data are subject to determination. Retraction is a rather interesting process. Consider it in more detail below.
The time during which coagulation occurs
The time during which blood clots, 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, that is, its clotting.
This indicator is not specific and gives a characteristic of the coagulation system in general. And what is a blood clot retraction?
This test requires one milliliter of blood to be drawn into a test tube. In the course of the study, both glass and silicone tubes can be used. After that, the blood should be kept at a temperature of 37 degrees Celsius. If blood coagulability is normal, then in a normal test tube it will be curtailed in 5-7 minutes, and in silicone – in 20-25 minutes.
Increased 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 diluting effect on the blood).
• Lack of coagulation factors. The decoding 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 there is a reduced clotting time, is very rare.
Contact activation index
Sometimes, when conducting a test, experts define an indicator such as an index of contact activation. This indicator reflects the ratio that occurs between the clotting time in a normal test tube and the clotting time in a silicone one. The normal level of this indicator is 1.7-3.0.
In case of disorders of the liver, some links of hemostasis and an excess of anticoagulants in the blood, an increased index of contact activation may be observed.
What is retraction? It interests many.
Recalcification time of blood plasma
The plasma recalcification time is the time period required for the formation of a blood clot after calcium salts have been added to the plasma. The range in a couple of minutes is considered a normal indicator.
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 method with which the test is performed. The normal ABP is a gap of 50-70 seconds.
Causes of prolonged recalcification time
In some cases, prolonged recalcification time may be observed. This is possible if:
• There is a lack of some coagulation factors.
• The blood contains an excessive amount of anticoagulants.
• There is a pathology of platelets.
In the event that the test shows a reduced recalcification time, then we can speak of an increase in the activity of the coagulation system. What else can decipher blood show?
This indicator is also called APTT (kaolin-kefalinovoy time) and is activated partial thromboplastin time. This test can be used to determine the function that plasma clotting factors perform.
The normal ASTV range is in the range of 35 to 45 seconds.
In some cases, an increase in APTT may be observed. This indicates:
• Excessive blood levels of anticoagulants.
• Some liver pathologies.
In the event that the APTT is at a level below 35 seconds, this may indicate an incorrect technique for collecting 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 the retraction of platelet cuts, resulting in the isolation of serum from the dense residue. When determining retraction, the volume of serum isolated from a blood clot should be measured. Retraction is an indicator that is mainly used to quantify the density of a clot, which is formed 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 ratio 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 assessed.
If the retraction of a blood clot is determined by the standard method, then an indicator 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 aleukia franc.
If there is an increased rate of blood clot retraction, this indicates the presence of anemia or an increased amount of fibrinogen contained in the blood. Completely absent retraction may occur in diseases such as Bright’s disease, Banti’s disease, pneumonia, leukemia, and diabetes. Retraction in medicine is an important indicator of the quality of blood and, accordingly, of health.
Thromboelastography and coagulography
Some laboratories, when determining the activity of the coagulation system, prefer not to use standard coagulogram tests, but special instruments, which are called:
These devices make it possible to obtain a graphic image of the blood coagulation process. If the necessary technique of recording is observed in the laboratory, 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. Thrombus retraction is also often measured.
Autocoagulation test or autocoagulogram is a rather rarely used method for studying the coagulation system.
When conducting such a study, blood requires prior special training. After that a specific reagent is added to it with equal intervals within an hour. With each addition is determined by blood clotting. After that, according to the data obtained as a result of the test, a graph is plotted. This graph reflects the existing relationship, as well as the balance that occurs between the blood coagulation system and the anticoagulant.
If an abbreviated autocoagulogram technique is used, all testing takes no more than ten minutes.
The method of construction and subsequent analysis of autocoagulogram is most often used if the patient is on long-term therapy with the use of heparin drugs or for the purpose of diagnosing hemophilia.
We considered such a thing as retraction. This is an important indicator of coagulation.