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Overfilled Tubes

Here is a question originally posted November 4, 2011 that did not attract discussion at the time:

I received a note from David Chance, Good Samaritan Medical Center, Corvallis OR, commenting that, unlike underfilled coagulation specimen (blue-closure) tubes; overfilling tubes, unless clots are present, does not affect coagulation results. Overfilling may occur when a specimen is collected by syringe and pushed into a tube. There is no comment on overfilling in CLSI H21-A5, however I suspect that many laboratories reject obviously overfilled tubes. Please comment on this, what is your policy on overfilled tubes?

Comments (2)
Specimen Management
Nov 14, 2011 1:25pm

Hi, Herb, and thank you for your comment. Though I agree hem
Hi, Herb, and thank you for your comment. Though I agree hemolysis and clotting risks increase with the use of a syringe, it is a standard method that is referenced in CLSI H21-A5. To reduce the risk of clotting, the syringe should be 20 mL or less. The danger of hemolysis during whole blood transfer is minimized by replacing the blood collection needle with a 20-gauge or larger transfer needle and allowing the blood to flow down the side of the tube. Needle-stick injury is minimized by placing the evacuated tube in a rack to make the transfer; it should never be held in the hand. Further, BD makes a shielded “safety transfer device” for this purpose. I hope this helps.

Nov 14, 2011 9:33am

Hi George, having David Chance as my technical supervisor he
Hi George, having David Chance as my technical supervisor here at St. Louis University Hospital Coagulation Reference lab has taught me to listen carefully because he is probably right.

The question of overfilled coagulation tubes is interesting. You mention overfilling can occur when a specimen is drawn in a syringe and pushed into a tube. I would think at best this is a pretty dicey procedure and at worst a dangerous procedure.

I would think the specimen would start to clot when drawn in a syringe because of drawing it slowly and no anticoagulant. I also think the specimen would be easily hemolyzed because of the velocity in which the specimen is drawn in and pushed out of the syringe. Also, results would be suspect because our reference ranges are set using tubes with a fixed vacuum that is standardized. Using a syringe is not standardized.

Herb Crown

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