Blood Specimens: Serum and Plasma

Questions and Answers

Clear, pale yellow

Fibrinogen

To separate the clotted blood from the serum

Whole blood Signup and view all the answers

To keep the blood from clotting Signup and view all the answers

To restrict venous flow but not arterial flow Signup and view all the answers

21 gauge Signup and view all the answers

Multisample needle Signup and view all the answers

Syringe System Signup and view all the answers

23 gauge Signup and view all the answers

Study Notes

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.

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.

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.

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.