Order of draw and tube additives on the CCMA

The exam rarely hands you a tube color. It hands you a test — PT/INR, CBC, basic metabolic panel — and expects you to convert it to a tube and then to a position in the CLSI sequence. A color mnemonic alone does not survive that.

1. Blood cultures	Yellow SPS bottle or tube, 8–10 inversions. Always first, before any additive can reach the bottle (CLSI PRE02, formerly GP41).
2. Light blue	Sodium citrate — PT/INR and aPTT. 3–4 inversions, and it must reach the fill line: the 9:1 blood-to-citrate ratio is part of the test.
3. Red or gold	Clot activator, plus gel in the gold SST. 5 inversions for plastic; a plain glass red tube has no additive and takes 0. Clot upright 30 minutes before centrifuging, and separate serum from cells within 2 hours (CLSI GP44).
4. Green	Lithium or sodium heparin, for plasma chemistries. 8–10 inversions.
5. Lavender or pink	K2 EDTA — CBC, HbA1c, type and screen. 8–10 inversions immediately, or the specimen microclots and the platelet count is rejected.
6. Gray	Sodium fluoride with potassium oxalate — glucose and lactate. 8–10 inversions. Last, because fluoride and oxalate interfere with the widest range of other tests.
Fingerstick runs backwards	The CLSI GP42 dermal order is blood gas, then EDTA, then other additives, then serum. EDTA comes first here — the opposite of venipuncture — because capillary blood starts clotting the moment it reaches the skin.
Butterfly plus light blue	When a winged set collects a coagulation tube first, draw a discard tube first to fill the tubing dead space, or the citrate tube comes up short.
Tourniquet	One minute maximum before the vein is entered. Longer hemoconcentrates the sample and falsely raises potassium, total protein and cell counts (CLSI PRE02).

Where the point is lost: Drawing lavender before the gold serum tube lets K2 EDTA carry over, and the panel comes back with a falsely high potassium and a falsely low calcium — it reads like a real electrolyte emergency. The other trap: an underfilled light blue tube is recollected, never topped off from a second tube and never diluted, because the excess citrate falsely prolongs the PT/INR.