Phlebotomy Test Order of Draw and Additives 2

Question 1

Which tube is collected FIRST in the venipuncture order of draw?

Accepted Answer

Blood culture bottles

Answer

Blood culture bottles are always collected first to minimize contamination risk from skin flora.

Question 2

What additive is found in a royal blue top tube used for trace element testing?

Accepted Answer

EDTA or no additive (K2EDTA or plain)

Answer

Royal blue tubes contain either EDTA or no additive and are made with trace-element-free stoppers to prevent contamination.

Question 3

A gray top tube contains which combination of additives?

Accepted Answer

Sodium fluoride and potassium oxalate

Answer

Gray top tubes contain sodium fluoride (a glycolytic inhibitor) and potassium oxalate (an anticoagulant) for glucose testing.

Question 4

In the order of draw, where does the EDTA (lavender) tube fall relative to heparin tubes?

Accepted Answer

After heparin tubes

Answer

EDTA tubes are drawn after heparin (green) tubes to prevent EDTA carryover from affecting coagulation or chemistry tests.

Question 5

Which tube additive works by binding calcium ions to prevent coagulation?

Accepted Answer

EDTA

Answer

EDTA chelates (binds) calcium ions, which are essential for the coagulation cascade, thereby preventing clotting.

Phlebotomy Practice Test