What color tube used to draw blood for cbc with diff?

Answer 1

In most cases, a lavender top (EDTA) tube, with at least 4 ml's.

Diff's can also be done on other tubes which have anti-coagulant additives, such as the citrate "Blue top" tube, if there is a specific need for a non-EDTA sample (for example; some rare patients platelets will clump in EDTA).

This is not preferred however as blue tops are less forgiving on short draws, and rapidly lose accuracy if not completely filled (which is one of the reasons why they are second in priority after blood cultures). EDTA tubes can, if necessary, be partially filled and still give accurate results.