Order of Draw

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The page below is a sample from the LabCE course Dermal Puncture and Capillary Blood Collection. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Order of Draw

The order of draw for a capillary blood collection is slightly different than the order of draw for a venous blood collection.
If capillary blood gases are ordered, they are drawn first to avoid introduction of room air as much as possible.
A specimen for blood count is collected before tubes containing other anticoagulants and additives. This is to ensure that the blood will not begin to clot before this specimen is collected; clots will affect the accuracy of the blood count. Blood specimens for newborn screening tests should be collected separately from a different site then the one for regular labs.
The following order of draw is commonly used:

Capillary blood gas collection tubesHeparinFor capillary blood gas tests
Blood smear---For hematology blood counts
Lavender top EDTA For hematology blood counts
Green topLithium heparinTests that require a heparinized plasma sample
__ Other tubes containing anticoagulants Varied
Red or gold topClot activatorTests that require a serum sample
Red topNo additiveTests that require a serum sample, but clot activator and/or gel may affect test