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syringe method with phlebotomy

Our policy states that a 10ml syringe is the maximum size we can use when obtaining a blood specimen via venipuncture utilizing the syringe method. I can't find the evidence to support this practice, I have looked in INS. Mostly we are utilizing a vacutainer method, occasionally on difficult sticks we will use the syringe method. Appreciate any input as I'm updating our training.



Allison Eustace



I can't see any reason for

I can't see any reason for this and would try to investigate why this has become the policy. Now smaller volume vacuum tubes are recommended to reduce risk of hospital acquired anemia.  If drawing from a VAD, this is a matter of physics and your policy is wrong. On injection (ie flushing), smaller syringes (3 or 5 ml) creaate greater pressure coming from the male luer tip of the syringe. This is the reason for recommended only a 10 mL syringe to assess patency before using a vad. On aspiration, the opposite is true - smaller syringes generate LESS pressure. So when using a syringe to draw blood, you should first use a very slow and gentle technique. If that does not work, switch to a SMALLER syringe to decrease pressure from aspiration. This pressure can cause catheter tip to get  sucked against a vein wall or it can cause the PICC to temporarily collapse. So smaller syringes are better for drawing blood samples from a PICC especially. Vacutainers are better because they eliminate need to transfer blood to the tube. This requires a needleless transfer device. NEVER use a needle on the syringe and NEVER remove the tube stopper to make this transfer. 

Lynn Hadaway, M.Ed., RN, BC, CRNI

Lynn Hadaway Associates, Inc.

126 Main Street, PO Box 10

Milner, GA 30257


Office Phone 770-358-7861

Syringe size

Yep, the larger syringes have higher negative pressure when drawing.  It may be confusing as they have lower positive pressure when flushing.  I have switched to 5cc syringes entirely, as the blood flow is clearly better and hemolysis decreased.  Also did a legal case where the presence of a slightly hemolyzed specimen was used to imply that the nurse wasn't really in the vein, although she drew 20cc of blood and it was processed (Attorneys !!!) My research revealed that drawing via a peripheral IV cannula has a higher incidence of hemolysis than through a steel needle & vacutainer.  

Mary Kate Schatzlein

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