What is the liquid portion of a clotted blood specimen called?

In a clotted blood specimen, the liquid portion obtained after centrifugation is referred to as serum. Serum is the clear, straw-colored liquid that remains after blood has clotted and the clot has been removed. It contains water, electrolytes, proteins, hormones, and waste products but does not include cells, platelets, or clotting factors, which are part of the clot that forms during the coagulation process.

Plasma, though it is the liquid component of unclotted blood, contains clotting factors and is obtained from blood that has been prevented from clotting through the use of anticoagulants. Whole blood includes all components: red blood cells, white blood cells, platelets, plasma, and all clotting factors, making it different from serum. Coagulated blood generally refers to blood that has undergone the clotting process, which includes both the solid part (the clot) and the serum. Heather specifically identifies serum as the liquid portion that is derived after the blood has clotted, making it the correct choice.