Phlebotomy and Blood Collection Flashcards

A patient has small, fragile veins. Which needle gauge is most appropriate for venipuncture?

Answer: 23 gauge

A 23-gauge needle is smaller and causes less trauma, making it ideal for patients with small or fragile veins.

Which condition can cause falsely elevated potassium levels in a blood specimen?

Answer: Hemolysis

Hemolysis releases intracellular potassium from red blood cells into the serum, causing falsely elevated potassium results.

When performing a capillary puncture on an infant, the preferred site is:

Answer: The medial or lateral plantar heel surface

The medial or lateral plantar surface of the heel is the recommended capillary puncture site for infants to avoid injury to nerves and bone.

Which additive in a blood collection tube inhibits thrombin and is used for coagulation studies?

Answer: Sodium citrate

Sodium citrate chelates calcium to inhibit the coagulation cascade and is the required anticoagulant for coagulation (PT/aPTT) testing.

A phlebotomist notices petechiae on a patient's arm after releasing the tourniquet. This finding most likely indicates:

Answer: Fragile capillaries or a coagulation disorder

Petechiae are pinpoint hemorrhages that suggest fragile capillaries or an underlying coagulation or platelet disorder.

The maximum time a tourniquet should remain applied before venipuncture to prevent hemoconcentration is:

Answer: 1 minute

Tourniquets should not remain in place longer than 1 minute to prevent hemoconcentration and falsely elevated analyte levels.

Which of the following tests requires a chain-of-custody procedure during specimen collection?

Answer: Forensic drug screening

Forensic drug screening requires a documented chain of custody to ensure specimen integrity and legal admissibility.