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).