3. Types of Anticoagulants, Blood Collection Tubes and Order of Draw

Question 1

Why must vacutainer tubes containing an anticoagulant be filled to capacity?

Answer 1

Vacutainer tubes contain a premeasured amount of anticoagulant; if the ratio of anticoagulant: blood is too low; the blood will form small clots; if the ratio is too high, the blood may hemolyze and the excess anticoagulant often interferes with subsequent analysis.

Question 2

How will the following affect the subsequent analysis?

 a. Using lithium heparin for a lithium analysis.

Answer 2

a. The results would be falsely high because the lithium in the anticoagulant will add to the lithium in the sample.

Question 3

How will the following affect the subsequent analysis?

Drawing 2.0 mL of blood into a regular blue topped tube.

Answer 3

There will be an excess of anticoagulant which will cause incorrect coagulation results (falsely prolonged times).

Question 4

How will the following affect the subsequent analysis?

Adding 7.0 mL of blood into a regular blue topped tube.

Answer 4

There will not be enough anticoagulant for the amount of blood (only 4.5 mL of blood should have been added) thus small clots will form and results obtained will be incorrect.

Question 5

How will the following affect the subsequent analysis?

Not mixing an EDTA tube immediately after blood collection.

Answer 5

The anticoagulant will not be mixed in with the entire blood sample so that parts of it will clot. The clots will clog many automatic instruments and will also give false blood count results (especially platelet counts).

Question 6

How will the following affect the subsequent analysis?

Not mixing an SST tube.

Answer 6

It will take longer to clot since the activator is not mixed in with the blood.

Question 7

How will the following affect the subsequent analysis?

Using a grey topped tube for an enzyme assay.

Answer 7

The fluoride acts as an enzyme poison and results will be incorrect.

Question 8

How will the following affect the subsequent analysis?

Using an EDTA tube for a calcium determination.

Answer 8

EDTA will chelate all the calcium thus giving falsely low values.

Question 9

Put the following tubes in the correct order to be drawn: blue, green, blood culture, SST, purple, grey, plain red

Answer 9

1. blood culture
   
   2. blue
   3. SST
   4. red
   5. green
   6. purple
   7. grey
   8. EDTA

Question 10

The preferred blood specimen for blood bank test is collected into which vacutainer tube?

Answer 10

Plain red glass tube.

Question 11

Which blood collection tubes doesn’t require mixing?

Answer 11

A PST contains heparin and a separating gel and yields plasma when centrifuged.

An SST contains a clot activator and a separating gel and yields serum when centrifuged.

Question 12

Which specimen is processed as whole blood?

Answer 12

The EDTA specimen in Hematology, because the cells are analyzed