A Thromboelastogram (TEG) is used to measure the physical properties of whole blood being able to clot. The measurement places the blood in a cup while in a suspended state. The whole blood is then heater to a temperature of nearly 40C thanks to a torsion wire that is connected to a transducer that is suspended over the sample. As the pin rotates, the strength and elasticity of the blood clotting ability of the blood can be measured.
Why Is the TEG Blood Test Ordered?
The TEG blood test is often ordered in conjunction with other traditional clotting tests, such as the INR blood test, the APTT, or a basic platelet count. All of these tests can provide predictors that thrombosis is present within a patient or that there is the possibility of uncontrolled bleeding occurring should an injury result.
This test is a point of care test that requires just 0.36 ml of whole blood to complete. It is also a rapid test that takes about 30 minutes for most providers. An activator is used with the TEG blood test for this increased speed. Activators are not necessary, but non-activated whole blood clots slower and so the measurement of its clotting function takes more time to complete.
Patients who have recently received a cardiovascular surgery or had an organ transplant, especially of the liver, may have this test conducted to determine if more blood products need to be introduced to their system. It can be a useful predictor for how the body is responding to trauma and can help medical providers develop a general transfusion strategy.
What Is the Benefit of the TEG Blood Test?
The entire system is hooked up to a computer that can interpret the rotational results that it receives as the blood begins to clot. This results in a numerical output and data visualization that helps results be understood more completely.
The TEG blood test can also be consistently repeated over a period of time so that a baseline average can be developed. There really is no limit to the number of times that this blood test can be completed, repeated, compared, or contrasted. Although the computer reading the test generally needs to be calibrated a couple of times per day and there will always be individual variability, the results received are a better indication of clotting ability than other current testing methods.
When Is the TEG Blood Test Not Useful?
There are certain health conditions or lifestyle habits that make the TEG blood test inaccurate. The most common reason that the test would not be ordered is because a patient is on an aspirin therapy to reduce the chances of future health conditions. The aspirin thins the blood and makes the readings become difficult to interpret.
What Do the TEG Blood Test Results Mean?
Most people who receive a TEG blood test will still receive a normal result, even if they are having difficult medical conditions with which they must cope.
The shape of the sample changes based on how the clotting happens. When hemophilia is present, for example, the factor deficiencies will prolong the shape of the sample so that in the data visualization results, a long line extends from a wide body. In comparison, platelet blockers cause the sample to have a thinner overall visualization sample with a slightly extended spire.
Very wide samples will be increased dramatically compared to normal samples. If Fibrinolysis is present, then there will be two long, then spires protracting from a reduced main body sample.
The TEG blood test was first developed in 1948 and has been used consistently to determine the need for blood products.
The additional information allows medical providers to understand when blood products are needed for survival so that supplies can be released when necessary. It has become an important part of the transfusion process, especially during complex procedure recoveries, and this has helped medical providers preserve the blood supply to make it more effective.