BD Vacutainer^® Citrate Blood Collection Tubes FAQ

The significance of the correct ratio of blood to additive for coagulation samples is well documented. The correct fill amount is critical for correct coagulation analysis. All BD Vacutainer^® plastic coagulation tubes have a mark indicating the minimum fill level.

Centrifugation conditions: Glass tubes: 1500 RCF for 15 min. Plastic tubes: 2000-2500 RCF for 10-15 min.

The etched fill indicator on the plastic citrate tubes indicates the minimum acceptable blood volume in the tube.

The following bullet points demonstrate that there is enough plasma to perform coagulation testing in a patient with an average hematocrit of 45%.

Tests in a 1.8 mL Plastic Citrate Tube Assuming a Patient Hematocrit of 45:

• Total plastic citrate tube blood volume is 2.0 mL
• Packed Cell Volume (PCV) = 2.0 mL x 0.45 = 0.9 mL
• Subtract PCV from whole blood volume to get volume of available plasma (2.0 - 0.9 = 1.1 mL)
• Allow 0.4 mL plasma to remain to avoid disturbing the buffy coat (1.1 - 0.4 = 0.7 mL)
• This still leaves 0.7 mL of plasma available for testing
• Automated instruments require an average of 100 µl per test for PT and APTT tests, 50 µl for Fibrinogen, and 20 µl for Factor Assays
• This volume, 0.27 mL, allows for a repeat test, if needed

For 2.7 mL Plus Citrate Tube Assuming a Hct of 45:

• Total plastic citrate tube blood volume is 3.0 mL
• PCV = 3 mL x 0.45 = 1.35 mL
• Subtract PCV from whole blood volume to get volume of available plasma (3.0 - 1.35 = 1.65 mL)
• Allow 0.4 mL plasma to avoid disturbing the buffy coat cells (1.65 - 0.4 = 1.25 mL)
• This leaves 1.25 mL of plasma available for testing
• Automated instruments require an average of 100 µl per test for PT and APTT, 50 µl for Fibrinogen, and 20 µl for Factor Assays (i.e., PT, APTT, Fibrinogen Plus 2 assays = 0.29 mL)

There have been recent articles indicating that drawing a discard tube is not necessary before drawing the sodium citrate tube. In the CLSI coagulation document (H21-A5) it is still recommended that the citrate tube is the second or third tube drawn. However, in the CLSI guideline for Venipuncture Collection (H3-A6) it states that for routine PT and APTT, the first tube drawn may be used for testing.

It is also important to ensure a discard tube is drawn when a blood collection set is used and only a citrate tube is ordered, as the tubing may contain up to 0.5 mL of air that will be drawn into the tube and displace blood volume.

The 1.8 mL tube has a light blue rubber stopper covered with a translucent BD Hemogard^™ and the 2.7 mL tube has a light blue rubber stopper covered with a solid light blue BD Hemogard^™ closure.

The blood to additive ratio is 9 parts blood to 1 part sodium citrate.

The 1.8 mL draw BD Vacutainer^® Citrate Blood Collection Tubes contains 0.2mL of sodium citrate, and the 2.7 mL draw contains 0.3 mL of sodium citrate.

Hemolyzed specimens should not be processed since there could be activation of the clotting factors. Lipemic or icteric specimens may also interfere with the instrumentation's optical system affecting the coagulation specimen result.

An inversion is one complete turn of the wrist, 180 degrees, and back. BD recommends that citrate tubes be inverted 3 to 4 times.