ASCP Phlebotomy 2

Question 1

What blood-to-anticoagulant ratio is required for sodium citrate (light-blue top) tubes used in coagulation studies?

Accepted Answer

9:1

Answer

A 9:1 blood-to-citrate ratio (9 parts blood to 1 part sodium citrate) is required; underfilling dilutes the anticoagulant and artificially prolongs clotting times.

Question 2

A patient has a hematocrit of 62%. How should the phlebotomist adjust sodium citrate tube collection?

Accepted Answer

Collect less blood to maintain the correct blood-to-citrate ratio

Answer

In patients with hematocrit >55%, less blood is drawn because the reduced plasma volume requires a smaller blood volume to maintain the 9:1 ratio with citrate.

Question 3

Which additive is found in a gray-top blood collection tube?

Accepted Answer

Sodium fluoride/potassium oxalate

Answer

Gray-top tubes contain sodium fluoride (glycolysis inhibitor) and potassium oxalate (anticoagulant), used for glucose and lactate specimens requiring glycolysis inhibition.

Question 4

How many times should a serum separator tube (SST/gold or red-gold) be inverted immediately after collection?

Accepted Answer

5–6 times

Answer

SST tubes should be inverted 5–6 times to ensure the clot activator (silica particles) mixes thoroughly with the blood without causing hemolysis.

Question 5

Which of the following specimens must be placed in ice water slurry immediately after collection?

Accepted Answer

Arterial blood gas (ABG)

Answer

ABG specimens must be chilled immediately because ongoing cellular metabolism alters pH, pO2, and pCO2 values within minutes at room temperature.

ASCP Practice Test

ASCP Practice Test

ASCP Phlebotomy 2