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Blood Samples & Blood Collection Tubes

Blood Samples & Blood Collection Tubes

Types of blood samples:

1. Whole Blood

A blood sample is drawn and mixed immediately with an anticoagulant to prevent clotting, allowing whole blood analysis to be accurate. The blood remains in a liquid state.

2. Serum

The liquid part of whole blood that has been allowed to clot. The clotting factors are bound in the clot. (Blood collected in a plain test tube will clot within 15-45 minutes. One 10 ml tube of whole blood will give about 3-4 ml of serum. This is the only tube that should not be inverted).

3. Plasma

The part  of blood that has not been allowed to clot. Commonly, formed when freshly drawn blood is mixed with anticoagulants. The clotting factors are present in the plasma. This sample is mixed 6-8 times and immediately centrifuged, and plasma is removed.

Order of draw:

• Blood test collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes.

• A Vacutainer blood collection test tube is a sterile glass or plastic tube with a closure that is evacuated to create a vacuum inside the tube facilitating the draw of a predetermined volume of liquid.

Blood Collection Tubes

- A plastic tube with a rubber stopper includes color-coded.

- Contain anticoagulants and/or other chemical additives.

- Plain tubes contain no anticoagulants.

- Additives preserve the specimen, prevent deterioration and coagulation, or block the action of certain enzymes in blood cells.

- After the tube filled with blood, immediately invert the tube several times to prevent coagulation.

- Tubes with anticoagulants should be gently and completely inverted (end over end) 4 to 6 times after collection. This process ensures complete mixing of anticoagulants with the blood sample and prevents clot formation.

- Complete filling of this tube is important to obtain accurate results. Some evacuate tubes contain a marked line, you must fill the tube into this marked line.

Types of collection tubes:

1. (Purple Top Tube):

- Additive: EDTA (Ethylene Diamine Tetra-Acetate).

- Mode of action: Formation of calcium salts to remove calcium.

- Specimen Type: Whole Blood, Plasma.

- Draw Amount: 4.0 ml/2.0 ml (pediatric tube)

- Uses complete blood count and Crossmatch; requires full draw – invert 8 times to prevent clotting and platelet clumping.

2. Light Blue Top Tube:

- Additive: Sodium citrate

- Mode of action: Formation of calcium salts to remove calcium

- Specimen Type: Whole Blood, Plasma

- Draw Amount: 2.7 ml/1.8 ml (pediatric tube only)

- Uses for prothrombin time, full draw required.

3. Dark Green Top Tube:

- Additive: Sodium heparin or lithium heparin

- Mode of action: Inactivates thrombin and thromboplastin.

- Specimen Type: Whole Blood, Plasma.

- Draw Amount: 4.0 ml/2.0 ml (pediatric tube)

- Uses: For lithium, use sodium heparin For ammonia l, use sodium or lithium heparin.

4. Gold Top Tube:

- Additive: None

- Mode of action: Serum separator tube (SST) contains a gel at the bottom to separate blood from serum on centrifugation.

Specimen Type: Serum

Draw Amount: 5.0 ml/8.5 ml

- Uses: Chemistries, Immunology, and Serology

5. Light Green Top Tube:

- Additive: Lithium heparin.

- Mode of action: Anticoagulates with lithium heparin.

Plasma is separated from PST gel at the bottom of the tube.

- Uses: Chemistries

6. Black Top Tube:

- Additive: Sodium citrate (buffered).

- Mode of action: Formation of calcium salts to remove calcium.

- Uses: Westergren Sedimentation Rate; requires full draw.

7. Red Top Tube:

- Additive: None

- Mode of action: Clots of Blood and the serum is separated by Centrifugation.

- Specimen Type: Serum

- Draw Amount: 6.0 ml

- Uses: Chemistries, Immunology, and Serology,

Blood Bank (Crossmatch).

8. Dark Blue Top Tube:

- Additive: Sodium EDTA

- Mode of action: Formation of calcium salts, Tube is designed to contain no contaminating metals.

- Specimen Type: Whole Blood, Plasma

- Draw Amount: 7.0 ml

- Uses: For lithium l, use sodium heparin Trace element testing (zinc, copper, lead, mercury) and toxicology.

9. Yellow Top Tube:

- Additive: ACD, solution A

- Mode of action: Complement inactivation

- Specimen Type: Whole blood

- Draw Amount: 8.5 ml
- Uses Tissue typing and some Red Cross testing. Refer to a specific test for the proper tube.

10. ESR Tube:

- Additive: 3.8% sodium citrate

General collection requirements

- Below is an illustrative list of hematological, and serologic tests done in many laboratories.

- The section labeled “Tube” is the mandatory tube to be drawn for the test indicated.


B-Light blue top

Gr-Grey Top

Gn-Green Top

L-Lavender Top

R-Red Top

S-Use Syringe



Special instructions

ABO type               


At least 7.0 ml clot

Antinuclear antibodies 


Avoid lipemic or hemolyzed serum    

Vitamin B-12         


Avoid hemolysis and protect from light 

Bilirubin, total or direct 


Protect from light





Clot retraction        


Place 3 ml in a 13x100 mm test tube; place in 37 degrees C water bath and allow to clot.                                     

Cold agglutinins       


Incubate blood at 37 degrees C until clotted, separate as soon as blood clots.         

C-reactive protein CRP 





Maximum Draw (exact draw)

Folate serum           


Avoid hemolysis





Human leukocyte antigen

R & Gr

Gn-donor, R recipient; do not freeze or refrigerate, record date and time collected                                  

Lactodehydrogenase LDH 



LDH isoenzyme          






Partial thromboplastin time PTT  


Maximum draw

Prothrombin time PT     


Maximum draw

Reticulocyte count     



Sedimentation rate     



T, T                    



T4 / t8 ratio          


Blood smear required, do not                freeze

Total iron binding     

  capacity TIBC     



Labeling the sample

A correctly labeled sample is essential so that the results of the test match the patient. The key elements in labeling are:

o Patient's surname, first and middle.

o Patient's ID number.

o NOTE: Both above MUST match the same on the requisition form.

o The date, time, and initials of the phlebotomist must be on the label of each tube.