Hemocompatibility: Trombogenicity – Platelets and Leucocytes counts. ASTM F2888-13: 2013 Method. Biological Evaluation of Medical Devices.

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Thromboembolic complications are one of the main problems that can occur with artificial organs and other medical devices that come into contact with blood. The evaluation of thromboembolic capacity is more complex to perform than other hemocompatibility tests such as hemolysis or pyrogenicity tests, due to the complexity of the blood coagulation system.

This test is one of the tests considered within the set of tests indicated to determine the hemocompatibility of a medical device that comes into contact with blood. The platelet and leukocyte count test indirectly determines that a thrombus can form, since these blood elements participate in its formation. Thrombus formation is determined by reducing the number of platelets and leukocytes when they are incorporated into thrombus formation after being activated on the surface of the medical device. This test identifies products capable of activating blood platelets and leukocytes on their surface when exposed to freshly collected human blood. A significant reduction in the number of platelets and leukocytes is indicative that these cells are trapped in the thrombus.

In this test, medical devices (materials) are exposed to blood immediately after blood is drawn with an anticoagulant. After a suitable time (1 hour), another anticoagulant is added to stop the reaction. In the tests, pieces of 12 square centimeters in triplicate are used for 1 mL of blood, or other proportions. In the test, negative and positive controls are used, also evaluated in triplicate. The results are calculated as the percentage of platelets or leukocytes with respect to the negative control.

Currently, there are no ranges, or concentrations, established as acceptable to intuit that a thrombus can be formed with the presence of a specific medical device. Only a significant decrease in the number of platelets and leukocytes can be indicative of an increased activation of platelets and leukocytes.