Blood collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes. The recommended order of draw for plastic vacutainer tubes is: First - blood culture bottle or tube (yellow or yellow-black top) Second - coagulation tube (light blue top). If just a routine coagulation assay is the only test ordered, then a single light blue top tube may be drawn. If there is a concern regarding contamination by tissue fluids or thromboplastins, then one may draw a non-additive tube first, and then the light blue top tube. Third - non-additive tube (red top) Last draw - additive tubes in this order: SST (red-gray or gold top). Contains a gel separator and clot activator. Sodium heparin (dark green top) PST (light green top). Contains lithium heparin anticoagulant and a gel separator. EDTA (lavender top) ACDA or ACDB (pale yellow top). Contains acid citrate dextrose. Oxalate/fluoride (light gray top)
