Collection ProceduresQuestion 22 of 100

A phlebotomist collects an aerobic and anaerobic blood culture set, then a green heparin tube, then a light blue citrate tube. What is the main problem?

a.The citrate tube was drawn after heparin, so heparin carryover can prolong clotting times
b.Heparin and citrate tubes cannot be drawn during the same venipuncture
c.Blood cultures should never be drawn first
d.There is no problem; the sequence is correct

Explanation

The citrate tube must immediately follow the blood cultures and precede all serum and heparin tubes. Because heparin inhibits thrombin, carryover into the citrate tube can falsely prolong the aPTT. Blood cultures are correctly drawn first, and both tubes may be collected in one venipuncture as long as the sequence is respected.

Law Reference: CLSI GP41

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