What is the primary characteristic of disseminated intravascular coagulation (DIC)?

The primary characteristic of disseminated intravascular coagulation (DIC) is the abnormal activation of coagulation proteins. In DIC, there is an uncontrolled and excessive activation of the coagulation cascade, which leads to the formation of small blood clots throughout the body's small blood vessels. This can result in a depletion of clotting factors and platelets, leading to a paradoxical increased risk of bleeding, despite the initial clotting.

The activation of coagulation proteins in DIC can be triggered by various conditions such as sepsis, trauma, or obstetric complications. This abnormal activation is what distinguishes DIC from other coagulation disorders, as it is characterized by both thrombosis and hemorrhage due to widespread clot formation and the consumption of clotting factors.

The other options do not accurately describe the hallmark of DIC. An increased platelet count is typically not seen in DIC; rather, there is usually thrombocytopenia due to consumption. Decreased blood flow to distal tissues may occur as a consequence of extensive clotting but does not define DIC itself. The formation of large blood clots in veins suggests a different pathology related to venous thromboembolism rather than the diffuse microscopic clotting seen in DIC.