Specimen Collection & Handling Flashcards

Which tube additive is found in a light blue (sodium citrate) tube and is used for coagulation studies?

Answer: Sodium citrate

Light blue tubes contain sodium citrate, which chelates calcium to prevent clotting and is required for coagulation tests like PT and aPTT.

A patient's arm is edematous at the antecubital fossa. What is the most appropriate action?

Answer: Select an alternative site such as the forearm or hand

Edematous sites can dilute the specimen with fluid and alter results, so an alternative non-edematous site should be selected.

When filling multiple tubes during a venipuncture, which tube should be filled immediately after the blood culture bottle?

Answer: Sodium citrate (light blue)

Per the CLSI order of draw, sodium citrate (light blue) tubes are filled first among additive tubes after blood cultures to avoid cross-contamination with other additives.

How long should a tourniquet remain in place before venipuncture to avoid hemoconcentration?

Answer: No more than 1 minute

Tourniquets should be released within 1 minute to prevent hemoconcentration, which can falsely elevate cell counts and analyte concentrations.

Which of the following is the correct angle of needle insertion for a routine adult venipuncture?

Answer: 15–30 degrees

A 15–30 degree angle is standard for venipuncture, allowing the needle to enter the vein without passing through the posterior wall.

A gray-top tube contains sodium fluoride. What is the primary purpose of this additive?

Answer: Inhibit glycolysis to preserve glucose levels

Sodium fluoride inhibits glycolytic enzymes, preserving glucose concentrations in the specimen for up to 24 hours.

When performing a skin puncture on an infant's heel, which area should be avoided?

Answer: The central posterior curvature of the heel

The central posterior curvature of the heel is too close to the calcaneal bone and risks osteomyelitis; only the medial or lateral plantar surfaces are safe for heel sticks.