Final answer:
The activated clotting time (ACT) test utilizes a blood tube containing diatomaceous earth to monitor anticoagulation therapy and assess bleeding risks.
Step-by-step explanation:
The test of the coagulation system that requires a blood tube containing diatomaceous earth is the activated clotting time (ACT). Diatomaceous earth acts as a contact activator, speeding up the activation of coagulation factors that lead to the formation of a thrombus, an aggregation of fibrin, platelets, and erythrocytes that leads to clot formation.
This test is utilized to monitor anticoagulation therapy during medical procedures such as cardiac surgery or to assess the coagulation status of patients with increased bleeding risk.