Collection ProceduresQuestion 2 of 100
A phlebotomist accidentally draws the lavender EDTA tube before the light blue citrate tube. What is the most likely consequence for the coagulation results?
a.The PT and aPTT will be falsely shortened by the added EDTA
b.The specimen will clot in the light blue tube within seconds
c.There is no effect because both tubes contain anticoagulants
d.EDTA carryover chelates calcium and can falsely prolong the PT and aPTT
Explanation
EDTA is a potent calcium chelator, and even a trace carried over on the needle into the citrate tube removes additional calcium and can falsely prolong clotting times. It may also falsely raise potassium and lower calcium if carried into a chemistry tube. The tubes are not interchangeable simply because both are anticoagulated; each anticoagulant works by a different mechanism and only citrate is validated for routine coagulation testing.
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