ASCP Phlebotomy Technician Order of Draw and Additives 2

Question 1

What additive is found in yellow-topped blood culture tubes?

Accepted Answer

Sodium polyanethol sulfonate (SPS)

Answer

Yellow-topped blood culture tubes contain SPS, an anticoagulant that also inhibits complement, phagocytes, and certain antibiotics, creating an optimal environment for bacterial growth.

Question 2

Why must light blue-topped coagulation tubes be filled to the exact fill line?

Accepted Answer

To maintain the correct 9:1 blood-to-anticoagulant ratio

Answer

Light blue coagulation tubes require a precise 9:1 ratio of blood to sodium citrate. Underfilling or overfilling alters this ratio and produces inaccurate coagulation results.

Question 3

Which tube additive works by activating clot formation rather than preventing it?

Accepted Answer

Clot activator (silica particles)

Answer

Clot activators such as silica or glass particles are coated on the inner walls of red/gold-topped tubes to promote and accelerate clot formation for serum testing.

Question 4

In the order of draw, why are EDTA (lavender) tubes drawn after heparin (green) tubes?

Accepted Answer

EDTA contamination would falsely affect electrolyte and enzyme results in heparin tubes

Answer

EDTA is drawn after heparin because EDTA contamination of chemistry tubes would falsely elevate potassium and chelate calcium, affecting multiple test results.

Question 5

What type of gel is found in gold-topped SST (serum separator) tubes and what is its function?

Accepted Answer

Thixotropic gel; it forms a barrier between serum and clot during centrifugation

Answer

SST tubes contain thixotropic gel that has a density between serum and clotted blood. During centrifugation, the gel migrates to form a stable barrier between the two layers.

ASCP Phlebotomy Technician Exam Practice Test

ASCP Phlebotomy Technician Exam Practice Test

ASCP Phlebotomy Technician Order of Draw and Additives 2