What is the main characteristic of plasma in blood collection?

The main characteristic of plasma in blood collection is that it is anti-coagulated blood. Plasma is the liquid component of blood that remains when the blood has been treated with anticoagulants, which prevents it from clotting. This allows for the retention of various substances, such as proteins, electrolytes, nutrients, hormones, and waste products, in a fluid state.

When blood is collected in a tube containing anticoagulants, and then centrifuged, the cells settle at the bottom and the plasma remains on top, clear and straw-colored. This characteristic is essential for many laboratory tests as they often require plasma to properly analyze the biochemical components without the interference of clotting factors that would occur in coagulated blood.

In contrast, options that suggest the presence of fibrinogen, coagulated blood, or a milky appearance are not representative of plasma. Plasma contains fibrinogen, which is a key protein involved in blood clotting, but it is kept in liquid form due to the presence of anticoagulants. Therefore, understanding that plasma is derived from anti-coagulated blood is crucial for laboratory practices and tests.