Serum & Plasma Preparation

Specimen Collection Lab Services

The most common serum preparation considerations include:

• Failure to separate serum from red cells within 15 to 30 minutes of venipuncture.

• Failure to allow clot specimens to clot before centrifugation.

• Hemolysis: red blood cells broken down and components spilled into serum. Causes and prevention are discussed under the section on hemolysis.

• Lipemia: cloudy or milky serum sometimes due to the patient’s diet.

The most common considerations in the preparation of plasma include:

• Failure to collect the specimen in correct additive.

• Failure to mix specimen with additive immediately after collection.

• Hemolysis or red blood cell breakdown.

• Incomplete filling of the tube, thereby creating a dilution factor excessive for total specimen volume (QNS).

• Failure to separate plasma from cells within 15 to 30 minutes of venipuncture for those specimens requiring this step.

• Failure to label transport tubes as “plasma.”

• Failure to indicate type of anticoagulant (eg, “EDTA,” “citrate,” etc).

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