May We Load Syringes with Anticoagulant?

May We Load Syringes with Anticoagulant?
Jul 9, 2017 7:37am

Though we collect most hemostasis specimens using evacuated tubes, we often resort to syringes when patient veins are small or fragile. Many of us specify syringe collection for global whole blood assays and platelet function tests. George recalls a time when we would load the syringe with a measured volume of sodium citrate anticoagulant prior to collection so that the freshly collected blood was immediately anticoagulated. We would observe the standard 9:1 ratio. For instance, we would draw 1 mL of anticoagulant into the syringe, carefully expel air, then collect 9 mL of blood. Subsequently we would expel the specimen to a non-anticoagulant tube. George has seen no protocol for this nor any document that either advocates for or prohibits this practice. Is there anyone who uses this approach? What are the pros and cons?

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Though we collect most hemostasis specimens using evacuated tubes, we often resort to syringes when patient veins are small or fragile. Many of us specify syringe collection for global whole blood assays and platelet function tests. George recalls a time when we would load the syringe with a measured volume of sodium citrate anticoagulant prior to collection so that the freshly collected blood was immediately anticoagulated. We would observe the standard 9:1 ratio. For instance, we would draw 1 mL of anticoagulant into the syringe, carefully expel air, then collect 9 mL of blood. Subsequently we would expel the specimen to a non-anticoagulant tube. George has seen no protocol for this nor any document that either advocates for or prohibits this practice. Is there anyone who uses this approach? What are the pros and cons?

By Dr Emmanuel Favaloro
Jul 9, 2017 2:54pm
Well, this is really taking us back in time. We used to do this in order to collect samples for platelet function, but this was when these tests were performed by research labs, in an 'idealized' test protocol, and we were also responsible for blood collections. These days, specialized blood collectors (phlebotomists) collect all our samples, and they are loath (for safety reasons) to collect using syringes, given all the new safety features available with evacuated tubes and retractable needles. Yes, syringes with pre-loaded citrate would be OK from a lab test perspective, but in today's world, essentially unlikely to pass our 'risk-aversion' strategies. Also, evacuated tubes do seem to yield normal platelet function studies. So, I certainly have no current protocols to share! Also, the needles need to be sterile, so any protocol would need to ensure a change in needle between take up of citrate, and extraction of blood, as well as a small air-pocket between the citrate solution and the new needle (we wouldn't want to inject non-sterile citrate into the patient!). Not really likely to harm them, but risk aversion...

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