Blood Specimens: Serum and Plasma

What is the typical color of serum?

What is contained in plasma but not in serum?

What is the purpose of centrifugation in serum separation?

Which type of blood specimen is used for most hematology tests?

What is the purpose of an anticoagulant tube in whole blood collection?

What is the primary purpose of a tourniquet in venipuncture?

What is the standard gauge of needle used for routine venipuncture?

What is the main component of the Evacuated Tube System that allows for multiple samples to be drawn?

What is the name of the system that includes a plastic syringe, a needle, and a transfer device?

What is the most commonly used gauge of needle for phlebotomy in the Butterfly System?

Types of Blood Specimens

Serum is a clear, pale yellow fluid that can be cloudy if non-fasting due to lipids.
Serum is separated from clotted blood by centrifugation at an RCF of 1,000 to 2,000g for approximately 10 minutes.
Many chemistry tests are performed on serum.

Characteristics of Plasma

Plasma is a clear to slightly hazy, pale yellow fluid.
Plasma separates from cells when blood in an anticoagulant tube is centrifuged.
Plasma contains fibrinogen, which is not present in serum due to clot formation.

Uses of Blood Specimens

Whole blood, containing both cells and plasma, is used for most hematology tests and many point-of-care tests (POCTs), especially in acute care and stat situations.
Whole blood must be collected in an anticoagulant tube to prevent clotting.

Venipuncture Equipment

A tourniquet restricts venous flow but not arterial flow, and should not be left on for more than 1 minute.
Tourniquets are typically 1 inch wide x 15 inch long.
Needle gauge and bore are inversely related, with a 21 gauge considered standard for routine venipuncture.
The Evacuated Tube System consists of a multisample needle, tube holder, and evacuated tubes.
The Syringe System includes a plastic syringe, a needle, and a transfer device.
The Butterfly System commonly uses a 23 gauge needle for phlebotomy.

Learn about the characteristics and differences between serum and plasma, two types of blood specimens used in medical testing. Understand how they are separated from whole blood and the types of tests performed on each. Test your knowledge of blood specimens and their roles in medical diagnosis.