Order of draw mnemonic: how to remember the tube sequence

The order of draw is the fixed sequence in which blood collection tubes are filled, designed so that the additive in one tube cannot contaminate the next — additive carryover. A mnemonic helps you recall the sequence under pressure, but it works best once you understand why the order runs the way it does.

A common mnemonic

One widely used aid is "Boys Love Ravishing Some Girls", mapping to the standard tube colours:

Order	Word	Tube (colour)	Additive
1	Boys	Blood culture (yellow)	Broth medium
2	Love	Light blue	Sodium citrate
3	Ravishing	Red / gold (serum, SST)	Clot activator ± gel
4	Some	Green	Heparin
5	Girls	Lavender then grey	EDTA, then fluoride

Any mnemonic you can recall reliably is fine — the words matter less than always producing the same correct sequence.

Why this order, not the words

The logic behind the sequence is what actually keeps a sample valid:

• Blood cultures first, because they demand the cleanest, least-contaminated draw of all.
• Citrate second, because coagulation tests are exquisitely sensitive to any other additive and to clotting.
• Serum next, then heparin, then EDTA, then fluoride — arranged so a trace of one additive carried on the needle cannot falsify the test in the following tube. EDTA carried into a later tube, for example, falsely lowers calcium and raises potassium.

Where the order changes

When a draw is collected with a syringe or a winged set and no other tubes are needed, a discard tube may be drawn first to clear the line's dead space before the citrate tube, so the coagulation sample fills completely. Always follow your local laboratory protocol where it differs.

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This guide is a free extract from PhlebMastery's phlebotomy theory course, with content aligned to published WHO guidance. The full treatment of tubes, additives, and the order of draw is in Module 3: Equipment & Blood Collection Systems. New here? Start with the free Module 1, or see the whole course — full access is a one-time purchase.